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Goodbye to long-serving Paul
– and hello to darker skies!
This issue, we bid a fond farewell to our reviews editor Paul Money,
who is retiring after 17 years on the team. Paul’s enthusiasm and
passion for the night sky meant that he arranged the sourcing and
shipping of close to 1,000 review items, personally tested almost 250
pieces of kit, wrote more than 40 features and appeared in 150
podcast episodes. It’s a remarkable achievement and I’m sure you’ll
join me in thanking him. Good luck in all your future adventures, Paul!
Speaking of adventures, many of us have one particular item on
our bucket list of sights we want to see: the aurora. These dazzling
light displays have recently been witnessed from Cornwall in the UK
to California in the US, places never normally treated to such
shimmering green spectacles. On page 32, Ezzy Pearson explores
the reasons behind these increasingly widespread displays and looks
ahead to what promises to be an aurora season like no other.
The residents of Presteigne and Norton in mid-Wales are now
much better able to see any aurorae above them, thanks to the work
they’ve done to protect their dark skies. Indeed, the two neighbouring
FRPPXQLWLHVUHFHQWO\EHFDPHWKHƅUVWLQWKH8.RXWVLGH6FRWODQGWR
be awarded International Dark Sky Community status. On page 36,
lighting designer Kerem Asfuroglu explains how local residents there,
as well as in two other communities, came together to get big wins
LQWKHƅJKWDJDLQVWOLJKWSROOXWLRQWRSURWHFWWKHLUGDUNVNLHV
Enjoy the issue!

Chris Bramley, Editor

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March 2024 BBC Sky at Night Magazine 3

32

COVER IMAGE: ASCENTXMEDIA/GETTY IMAGES. THIS PAGE: MARKUS VARIK/HTTPS://GREENLANDER.NO/WWW.INSTAGRAM.
COM/GREENLANDER_TROMSO/WWW.FACEBOOK.COM/GREENLANDERTROMSO, ESO/L. CALÇADA/M. KORNMESSER, DANI
ROBERTSON, @THESHED_PHOTOSTUDIO, SKAO, ESA/EUCLID/EUCLID CONSORTIUM/NASA. BACKGROUND GALAXIES: NASA/ESA
AND S. BECKWITH (STSCI) AND THE HUDF TEAM, CHINESE ACADEMY OF SCIENCES

CONTENTS

C = on the cover

Regulars
6 Eye on the sky
10 Bulletin
C If we’re all made of ‘star stuff’,
where did it come from?
14 Cutting edge C
16 Inside The Sky at Night
36 Lighting for the dark
18 Interactive
C Hear about three communities
that have restored their dark skies 21 What’s on
23 Field of view
60 Radio revolution
24 Subscribe to BBC Sky
C What we’ll discover from the
at Night Magazine
world’s largest radio telescope
32 Explainer EXTRA C
66 The edge of the Solar System 74 Skills for stargazers
C We take a peek at what’s outside 98 Q&A: an observatory
our cosmic neighbourhood
president
Astrophotography
68 Big data at the dawn of
76 Capture
C DUWLƅFLDOLQWHOOLJHQFH
78 Processing
How AI will supercharge our
80 Gallery
quest to understand space
Features
26 Cosmic factories

4 BBC Sky at Night Magazine March 2024

Reviews
86 RVO Horizon 80 ED refractor
(full imaging package)
90 QHYCCD QHY5III200M
mono camera
95 Gear
96 Books
16-PAGE
CENTRE
The Sky Guide
PULLOUT
44 Highlights
46 The big three C
48 The planets
50 March’s all-sky chart
52 Moonwatch
53 Comets and asteroids
53 Star of the month
54 Binocular tour
55 The Sky Guide challenge
56 Deep-sky tour
58 March at a glance

New to astronomy?
To get started, check out our guides and glossary at
www.skyatnightmagazine.com/astronomy-for-beginners

26

FREE BONUS

CONTENT
Find it at www.skyatnightmagazine.
com/bonus-content

MARCH
HIGHLIGHTS
Interview: X-ray eyes on the sky
Dr Charly Feldman on China’s Einstein probe and how
X-ray vision unlocks the secrets of the Universe.

36

86

60

68

This month’s contributors

Download our lunar
phases 2024 poster

More amazing images
of the Universe

Keep up to date with
Moon times and phases
by downloading and
printing our PDF poster
covering all of 2024.

View our galleries of the
latest images captured
by astrophotographers
and professional
observatories alike.

Harry Cliff

Kerem Asfuroglu

Paul Cockburn

Particle physicist

Lighting designer

Science writer

The Virtual Planetarium

“I can’t think
of a more
romantic
VFLHQWLƅF
discovery than the
realisation that every
atom in our bodies was
ultimately forged by
awesome forces inside
stars.” Read about the
atomic history of the
Universe on page 26

“Light
pollution is
a growing
problem, but
thanks to the growing
pool of committed
communities, we’ve
never been better
equipped to tackle it.”
Kerem explores places
where lighting respects
the night, page 36

“The scale of
information
generated
by current,
let alone future, space
surveys is demanding
new approaches to
data. It’s fascinating
how astronomers are
meeting the challenge.”
Paul explains how
on page 68

Pete Lawrence and Paul Abel guide us through
the best sights to see in the night sky this month.

March 2024 BBC Sky at Night Magazine 5

6 BBC Sky at Night Magazine March 2024

EYE ON THE SKY
It’s a case of poultry perfection as the Running
Chicken Nebula is revealed in high resolution

his 1.5-billion-pixel image of the Running Chicken
Nebula, which lies 6,500 lightyears from Earth in the
constellation of Centaurus, is a mosaic compiled
from hundreds of frames taken by the OmegaCAM
instrument on ESO’s VLT Survey Telescope.
The area depicted measures 270 lightyears across and within
it you can clearly see the disparate elements that make up the
Running Chicken: pink, round emission nebula IC 2948 (the ‘body’
of the chicken, lower left), open cluster IC 2944 (the fainter ‘neck’,
centre) and Bok globules GUM 39, 40 and 41 (right).
Also visible is Lambda Centauri, the bright blue star in the
middle – although this is much closer to Earth, at just 470
lightyears’ distance.

FREE BONUS CONTENT
Explore a gallery of these and more
stunning space images
www.skyatnightmagazine.com/bonus-content
March 2024 BBC Sky at Night Magazine 7

ESO/PHAS+ TEAM/ACKNOWLEDGEMENT: CASU

VLT SURVEY TELESCOPE, 21 DECEMBER 2023

U As clear as mud

NASA/JPLCALTECH/UNIVERSITY OF ARIZONA, IMAGE DATA: NASA/JPLCALTECH/SWRI/MSSS/IMAGE PROCESSING BY TED STRYK, ESA/HUBBLE & NASA/J.
DALCANTON/DARK ENERGY SURVEY/DOE/FNAL/NOIRLAB/NSF/AURA/ACKNOWLEDGEMENT: L. SHAT, NASA/ESA/STSCI/A. SIMON (NASAGSFC)

MARS RECONNAISSANCE
ORBITER, 19 DECEMBER 2023
The conical mounds with
central, bowl-like depressions
seen in this image of the
Martian surface are believed
to be mud volcanoes, similar
to those found in many
continents on Earth. Mud
volcanoes are not igneous and
spew no lava, but are instead
formed when subterranean gas
and liquid bubble up through
muddy terrain.

Peak
performance Z
JUNO, 22 DECEMBER 2023
This image of Jovian moon Io’s
north polar region was originally
captured by NASA’s Juno
spacecraft in October last year.
Processing by citizen scientist
Ted Stryk then revealed three
previously unseen peaks
(towards the top, close to the
terminator) that are believed to
result from volcanic activity.

8 BBC Sky at Night Magazine March 2024

U Spiral
illusion
HUBBLE SPACE
TELESCOPE, 25
DECEMBER 2023
This image contains
four spiral galaxies:
IC 1947 on the left
and sprawling NGC
1356 on the right,
with LEDA 467699
above and LEDA
95415 directly to its
left. You might
assume the last
three lie close
together, but LEDA
95415 is actually 300
million lightyears
further away than
its large apparent
‘neighbour’ – indeed
the two are likely far
more closely
matched in size
than they appear.

U Saturn’s spokes
HUBBLE SPACE TELESCOPE, 21 DECEMBER 2023
Look closely at this image of Saturn
captured by the Hubble Space
Telescope and you’ll spot some
faint grey smudges on the rings to

the left and right of the planet.
These so-called ‘spokes’ – seasonal,
transient features that rotate with
the rings for just 30 hours or so – are

thought to be clouds of displaced
dust or ice, although the
mechanism behind their formation
remains a mystery.

March 2024 BBC Sky at Night Magazine 9

The latest astronomy and space news, written by Ezzy Pearson

ILLUSTRATION

BULLETIN
Comment
by Chris Lintott

How it should have
landed: the craft was
intended to lie on its side

Japan’s Moon mission a success in the end
JAXA, JAXA/TOMY/SONY/DOSHISHA UNIVERSITY/VIA KYODO, MARK GARLICK/SCIENCE PHOTO LIBRARY/ISTOCK/
GETTY IMAGES, THOMAS MÜLLER (HDA/MPIA) S. STUBER ET AL/ (MPIA) NASA/ESA/S. BECKWITH (STSCI) AND THE
HUBBLE HERITAGE TEAM (STSCI/AURA), LAMONT POOLE/NASA LANGLEY RESEARCH CENTER

SLIM lander’s power system failed after touchdown but then recovered
Japan became theƅIWKQDWLRQWRVXFFHVVIXOO\
soft-land a spacecraft on the Moon, on 19 January
DW87,QLWLDOO\LWVHHPHGFHOHEUDWLRQVZRXOGEH
short-lived due to a problem with the spacecraft’s
solar power system, but the team were able to
re-establish contact nine days later.
The Smart Lander for Investigating Moon (SLIM),
from the Japanese Aerospace Exploration Agency
(JAXA), launched on 6 September 2023 and entered
lunar orbit on 25 December. Its primary goal was to
conduct a precision landing near Shioli crater.
Soon after the expected touchdown time, NASA’s
Deep Space Network received telemetry from the
VSDFHFUDIWFRQƅUPLQJLWKDGODQGHGLQRQHSLHFH
8QIRUWXQDWHO\WKHVSDFHFUDIWKDGODQGHGRQLWVQRVH
angling its solar panels away from the Sun, and was
only able to operate under battery power for a few
hours. The team hoped to re-establish contact when
the Sun moved into a more favourable position. SLIM
came back online on 28 January and the team
immediately recommenced science observations as
there were only a few days left until the Sun set, and
SLIM is not designed to survive the lunar night.
The spacecraft was also carrying two rovers, a
small hopper and a basketball-sized rolling rover.

10 BBC Sky at Night Magazine March 2024

How it actually landed:
a lost engine left SLIM
nose-down near Shioli crater

Both are believed to have deployed successfully.
The hopper rover was designed to communicate
directly with Earth, and so JAXA was able to use
its cameras to photograph SLIM’s position.
6/,0ŝVSDUWLDOVXFFHVVFRPHVMXVWDIWHUWKH
failure of the Peregrine mission, a lunar lander from
86VSDFHƆLJKWFRPSDQ\$VWURERWLF6KRUWO\DIWHU
launching on 8 January, its fuel tank ruptured. The
team were able to safely deorbit the spacecraft 11
days later. The setback could delay the launch of
NASA’s water-hunting VIPER rover that Astrobotic
was due to ferry to the Moon in November.
global.jaxa.jp

Faster, cheaper,
better: NASA’s
slogan from the
1990s has come to
haunt anyone who
dreams of lobbing
satellites into space.
Though the aim
was for more rapid
mission design,
failures like Mars
Climate Orbiter
(which crashed
after an infamous
mix-up over metric
and imperial units)
made the approach
something of a
MRNH(QJLQHHUV
muttered that you
could only have
two of the three
– faster and
cheaper inevitably
meant riskier.
Now NASA is
handing off
responsibility to
companies like
Astrobotic, while
JAXA uses
missions like SLIM
to experiment with
new technology,
risky missions seem
accepted – and
sometimes, like
SLIM, pay off in
the end.
Chris Lintott
co-presents
The Sky at Night

NEWS IN

ILLUSTRATION

BRIEF
Alien oceans may
sequester carbon
dioxide like Earth’s do

Carbon-light atmospheres may mean habitability
Water oceans suck carbon dioxide from planets’ atmospheres
Astronomers could soon be tracking down
exoplanets with liquid water oceans not by
looking for the presence of water, but instead
by searching for the absence of carbon dioxide
in their atmospheres.
The search for habitable worlds has been
governed by the search for liquid water, but
there are no observatories that can detect
surface water directly. However, space
telescopes such as the JWST are able to
observe carbon dioxide in a planet’s atmosphere.
“On Earth, much of the atmospheric carbon
dioxide has been sequestered in sea water and

solid rock, which has helped to regulate climate
and habitability for billions of years,” says
Frieder Klein from Woods Hole Oceanographic
Institution, who took part in the study
alongside astronomers from MIT.
7KLVPHDQVRXUSODQHWKDVVLJQLƅFDQWO\OHVV
carbon dioxide in its atmosphere than the
similarly sized Venus and Mars. By looking for
extrasolar systems with several similarly sized
terrestrial planets, it could be possible to spot
one where a water ocean has absorbed most of
the carbon dioxide from the atmosphere.
news.mit.edu

Mapping star formation in the Whirlpool Galaxy
Astronomers have mapped
the cold, dense gas that will
one day become stellar
nurseries in the Whirlpool
*DOD[\07KLVLVWKHƅUVW
time such an extensive map
has been created for a galaxy
beyond the Milky Way.
“To investigate the early
phases of star formation,
where gas gradually
condenses to eventually
SURGXFHVWDUVZHPXVWƅUVW
identify these regions,” says
Sophia Stuber from the Max
Planck Institute for Astronomy,
who led the study. “We
typically measure the
UDGLDWLRQHPLWWHGE\VSHFLƅF
molecules that are particularly
abundant in these extremely
cold and dense zones.”
The team spent over 200
hours observing the nitrogenand hydrogen-bearing
molecules hydrogen cyanide
and diazenylium across the

Areas of diazenylium
molecule radiation detected
in the Whirlpool Galaxy

Stratospheric rainbows
Sky-watchers in the last few
months of 2023 reported an
explosion in the number of
polar stratospheric clouds
– rainbow-hued clouds
formed from ice crystals in
the upper atmosphere.
Temperatures in the
stratosphere reached a
40-year low of –85°C,
causing more ice to form
and create the clouds.

How centaurs get tails
Centaurs – space rocks the
size of asteroids but with the
composition of comets
– appear to become more
active after an encounter
with Jupiter or Saturn. A
study tracked the history
of all known centaurs and
found those with comet-like
tails had their orbital paths
changed following an
interaction with one of
the gas giants.

Furthest FRB found

Whirlpool Galaxy, using the
Northern Extended Millimetre
Array in the French Alps.
Though further away than
similar clouds in our own
Galaxy, the Whirlpool Galaxy
provides a much better view as
we are seeing them straighton. This allows astronomers to
easily trace the structure of

gas clouds along the arms and
centre of the galaxy.
“Although we can learn a lot
from the detailed observation
programme with the Whirlpool
Galaxy, it is, in a sense, a pilot
SURMHFWŠ6WXEHUSRLQWVRXW
“We would love to explore
more galaxies in this way in
the future.” www.mpia.de

Astronomers have pinned
down the furthest-ever fast
radio burst (FRB), bright radio
ƆDVKHVWKDWODVWMXVWDIHZ
milliseconds. FRB 20220610A
ƆDVKHGZKHQWKH8QLYHUVH
ZDVRQO\ƅYHELOOLRQ\HDUVROG
and seems to originate from
a compact cluster of early
galaxies, suggesting a
galaxy merger may have
triggered the event.

March 2024 BBC Sky at Night Magazine 11

BULLETIN

Supernova
light travel time:
615 million years

S One of the thousands of supernovae discovered that challenge the accelerating expansion model of the cosmos

Dark energy could change with time
DES COLLABORATION/NOIRLAB/NSF/AURA/M. ZAMANI, PITRIS/ISTOCK/GETTY IMAGES, NASA/
ESA/QUENTIN CHANGEAT (ESA/STSCI) MAHDI ZAMANI (ESA/HUBBLE), UNIVERSITY OF ARIZONA

The find comes from the largest sample of supernovae ever detected by a single telescope
Dark energy – the mysterious substance
that’s apparently driving our Universe
apart – could vary with time, according
to the latest results from the Dark Energy
Survey (DES).
In 1998, two teams of astronomers
measured the expansion of the Universe
by looking at Type Ia supernovae. These
occur when a white dwarf steals stellar
material from a nearby companion star
until it reaches a critical mass and
explodes in a supernova. Because they
are always the same mass when they
explode, Type Ia supernovae all have the
same intrinsic brightness. By comparing
this to their apparent brightness,
astronomers arrive at an accurate
measure of their distance.
The 1998 study also measured their
redshift and was able to gauge how fast
the supernovae’s home galaxies were
moving away from us. Together, this
12 BBC Sky at Night Magazine March 2024

allowed the teams to measure how fast
the Universe was expanding. However,
UDWKHUWKDQƅQGLQJWKHH[SDQVLRQZDV
slowing as expected, the team found it
was actually accelerating. To explain this
fact, cosmologists hypothesised ‘dark
energy’, which is driving the fabric of the
Universe apart.
Beginning in 2013, the DES sought to
create the most accurate measurements
of our Universe’s expansion. The initiative
spent six years mapping one-eighth of the
sky, observing two million distant
galaxies. This latest study scoured the
data for Type Ia supernovae and
uncovered 1,499 – the largest sample ever
detected with a single telescope.
“It’s a really massive scale-up from 25
years ago when only 52 supernovae were
used to infer dark energy,” says Tamara
Davis, from the University of Queensland
and member of the DES project.

The standard model of cosmology,
known as the Lambda cold dark matter
model (ΛCDM), assumes the density of
dark energy in the Universe remains
constant over time. If this was the case,
then it would mean the total proportion
of dark energy would increase as the
Universe gets bigger. But the DES results
suggest this might not be so.
“There are tantalising hints that dark
energy changes with time,” says Tamara
Davis, also from the University of
Queensland and member of the DES
SURMHFWş:HƅQGWKDWWKHVLPSOHVWPRGHO
of dark energy – ΛCDM – is not the best
ƅW,WŝVQRWVRIDURIIWKDWZHŝYHUXOHGLWRXW
but in the quest to understand what is
accelerating the expansion of the
Universe this is an intriguing new piece of
the puzzle. A more complex explanation
might be needed.”
www.darkenergysurvey.org

NEWS IN

BRIEF
With the right porosity,
organic clumps may build
the short-lived islands

Titan’s magic floating islands
Bennu sample finally out

Transient isles form then dissolve on Saturn moon’s seas
It is possibleIRUGLVDSSHDULQJLVODQGVWRƆRDW
on the methane seas of Titan, Saturn’s largest
moon, a new study has found.
Titan’s atmosphere is rich with organic
material and its surface is covered in rivers and
oceans of methane and ethane. In 2014, NASA’s
Cassini spacecraft spotted bright, transient
dots in the moon’s seas, called ‘magic islands’.
“I wanted to investigate whether the magic
LVODQGVFRXOGDFWXDOO\EHRUJDQLFVƆRDWLQJRQ
WKHVXUIDFHOLNHSXPLFHWKDWFDQƆRDWRQZDWHU
KHUHRQ(DUWKEHIRUHƅQDOO\VLQNLQJŠVD\V

Xinting Yu, from the University of Texas at San
Antonio, who led the study. “For us to see the
PDJLFLVODQGVWKH\FDQŝWMXVWƆRDWIRUDVHFRQG
DQGWKHQVLQN7KH\KDYHWRƆRDWIRUVRPHWLPH
but not for forever either.”
Yu’s team determined that any organics that
rained down from the atmosphere wouldn’t
immediately dissolve. If these clumps had the
right amount of porosity, it would be possible
IRUWKHPWRƆRDWRQWKHVHDV7KHFOXPSVFRXOG
amass near the shore, then break off to form
the islands. utsa.edu

Wales’s first dark-sky
community
Presteigne and Norton
KDYHEHFRPHWKHƅUVWHYHU
International Dark Sky
Community in Wales. The
40km2 area is home to 2,700
people who have worked
together to ensure they
meet the strict requirements
to be named a dark-sky site.
Turn to page 36WRƅQGRXW
more about other
communities working to
keep their skies dark.

Hubble shows storm-ravaged exoplanet
Giant cyclones swirl around the distant planet
WASP-121b only to vanish, according to a new
study using data from the Hubble Space
7HOHVFRSH7KHƅQGLVDQLPSRUWDQWVWHSLQ
studying exoplanet weather patterns.
WASP-121b is a hot Jupiter that orbits its star
once every 1.27 days. It’s tidally locked, with its
day side constantly pointing towards its star,
reaching temperatures of 1,870°C. Using
observations of the planet taken when it was in
different parts of its orbit, planetary scientists
were able to measure how the atmosphere’s
composition and temperature changed across
the day and night sides. Astronomers combined
this data with computer simulations to reveal a
world ravaged by huge storms, which rise only
to destroy themselves.
Though WASP-121b is a gas giant, similar
techniques could one day be used to
understand other kinds of worlds.
“Studying exoplanets’ weather is vital to
understanding the complexity of exoplanet
atmospheres on other worlds, especially in the
search for exoplanets with habitable
conditions,” says Quentin Changeat from

After months of careful
work, NASA has now
completely extracted from
its return capsule the sample
of asteroid Bennu brought
back by the OSIRIS-REx
mission. The precious space
rock will now be divided up
DQGVHQWWRZDLWLQJVFLHQWLƅF
institutions for analysis.

Brown dwarf has aurora
Weather-beaten WASP-121b
orbits dangerously close
to its host star

the Space Telescope Science Institute in
Baltimore, Maryland, who worked on the
project. “The assembled dataset represents
DVLJQLƅFDQWDPRXQWRIREVHUYLQJWLPHIRUD
single planet and is currently the only
consistent set of such repeated observations.
This provided us with an exquisite picture of
the planet changing over time.”
hubblesite.org

NASA’s JWST has found the
ƅUVWHYLGHQFHRIDQLQIUDUHG
aurora dancing around a
brown dwarf, W1935, a
stellar object with a mass
between Jupiter and a star.
W1935 has no companion
star to provide a stellar wind
– which generates Earth’s
aurorae – however either
interstellar gas or a nearby
moon could aid in creating
the infrared glow.

March 2024 BBC Sky at Night Magazine 13

Our experts examine the hottest new research

CUTTING EDGE

ILLUSTRATION

Amino acids survived
sulphuric acid baths,
so could life survive
above Venus?

the complex molecules and chemical reactions of
life – could be stable in concentrated sulphuric acid.
But a team lead by Sara Seager at MIT has been
challenging this by testing the assumption with
experiments. Seager is a very active astronomer and
has performed a lot of work on extrasolar planets
and their atmospheres. In recent years, she has been
exploring the possibility of life on Venus, including
being involved in the 2020 study that made the
controversial claim for the detection of phosphine
gas in the Venusian cloud decks.
Last year, Seager and her colleagues showed that
the building blocks of DNA and RNA, nucleic acid
bases, are in fact stable for at least weeks in the
concentrated sulphuric acid environment of the
9HQXVLDQFORXGV1RZZLWKKHURZQVRQDVWKHƅUVW
author, she has published a study on whether amino
acids, which build the proteins of life, are also stable.

The acid test

Max Seager, at the Worcester Polytechnic Institute,
Massachusetts, and his colleagues ran a very simple
experiment. They bought standard preparations
of 20 different amino acids used by
terrestrial life from a chemical
reagent supplier, dissolved them
“They bought
in concentrated sulphuric acid
20 amino acids,
and left them at room
temperature for several
dissolved them in
weeks. They reanalysed
concentrated
the amino acids after 12
sulphuric acid and
hours, a week and a
left them at room
month, to see which had
remained stable, or had
temperature for
EHFRPHFKHPLFDOO\PRGLƅHG
several weeks”
They found that even after a
month, 19 out of the 20 had
remained unreactive or were only
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happen in water) – the backbone of the amino acid
molecule remains intact.
As the authors point out, “complex organic
chemistry is, of course, not life, but there is no life
without it”. These experiments do demonstrate the
Prof Lewis Dartnell
possibility for biochemistry based on a concentrated
is an astrobiologist
at the University
sulphuric acid solvent. Perhaps there is still hope yet
of Westminster
for the existence of Venusian aerial life.

Life in Venus’s acid clouds
Complex organic molecules may exist
in the hellish atmosphere above Venus

MARK GARLICK/SCIENCE PHOTO LIBRARY/ISTOCK/GETTY IMAGES, NASA/ESA AND STSCI

S

cientists have long speculated about
whether Venus could harbour life. Its
thick, carbon dioxide atmosphere creates
a powerful greenhouse effect and the
surface is searingly hot (over 450°C).
Indeed, the planet is often described as ‘Earth’s
evil twin’. So while the surface clearly doesn’t offer
any chance of liquid water or organic molecules
– the fundamental prerequisites for life – the high
atmosphere could offer a habitable environment.
Venus is shrouded in thick cloud layers; between
altitudes of 48km and 60km the atmospheric
pressure and temperature are similar to those on
Earth’s surface. There’s plenty of sunlight to serve
as a power source for life too.
The problem, however, is that the cloud droplets are
made up of concentrated sulphuric acid. This is still
an exceptionally hostile environment, with virtually no
available water, and is orders of magnitude more
acidic than that in which extremophile organisms on
Earth can survive. But could the Venusian clouds still
support microorganisms using an exotic biochemistry
based on organic molecules dissolved in, not liquid
water, but concentrated sulphuric acid as a solvent?
The assumption has been that only simple organic
chemistry – with limited functionality for supporting

14 BBC Sky at Night Magazine March 2024

Lewis Dartnell was reading… Stability of 20 Biogenic Amino Acids in
Concentrated Sulfuric Acid: Implications for the Habitability of Venus’
Clouds by Maxwell D Seager, Sara Seager et al.
Read it online at: arxiv.org/abs/2401.01441

CUTTING EDGE

affected. If something like a passing planet within
the lens galaxy is causing the variation, the images
we see should change brightness separately.
But the authors need to be clever. Their models
FDQŝWVLPSO\DVVXPHWKHSUHVHQFHRIIUHHƆRDWLQJ
planets (or planet-mass objects) – that’s ruled out by
those Milky Way observations. Instead, they revive an
The blink of distant quasars may hint Prof Chris Lintott older idea of dark matter consisting of a population
at one of the cosmos’s big mysteries is an astrophysicist of clouds of gas, each with the mass of a planet, but
and co-presenter
at a much lower density. Such objects, which they
on The Sky at Night
ost cosmologists believe that
confusingly call ‘planets’, would not cause noticeable
dark matter, the mysterious
lensing of stars in the Milky Way, but would affect
substance that seems to account
light from quasars. Simulations seem to show that
“They revive
for six-sevenths of the matter
events like dips in quasar brightness that last for
an older idea of dark \HDUVVHHPWRƅWZKDW\RXŝGH[SHFWLIWKHUHZDV
in the Universe, exists in the
form of myriad weakly interacting massive
such a population of objects. And they might
matter consisting of
particles, or WIMPs.
be common enough to make a substantial
a population of
The WIMPs won out over ideas of a
contribution to dark matter.
clouds of gas, each
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New, much more precise observations of
with the mass of a
(collectively known, appropriately, as
quasars like Q2237 will be needed before the
MACHOs, Massive Compact Halo Objects)
idea can be properly tested – a job for which
planet, but at a much
because of a set of experiments that used
the
Hubble Space Telescope is well equipped.
lower density”
modest telescopes to stare at stars in the Milky
For now, it’s a useful reminder that we know less
Way’s halo. The aim was to spot the effect of a
about dark matter than we think we do.
passing MACHO on a background star; if the
alignment was perfect, gravitational lensing would
Quasar G2237, cloned four times
cause the background star to brighten and then fade
by gravitational lensing, made
the ideal test subject for the
in a predictable pattern.
roaming gas clouds theory
The physics is sound – Einstein’s theory of relativity
tells us that light should be bent by massive objects
in just this way. But very few events were seen, so
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black holes surrounding our Galaxy to account for
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planet-sized objects exist, we should detect them
passing between us and distant objects too – and
variations in the brightness of quasars, extremely
distant objects, have been attributed to the presence
of hosts of passing planets in the distant Universe.

Are roving gas clouds
behind dark matter?

M

Quasar clues
In this month’s paper, the authors aim to reconcile
WKLVH[SODQDWLRQIRUTXDVDUƆLFNHULQJZLWKWKH
apparent absence of such planets around the Milky
Way. First, they set out to distinguish the effects of
lensing by dense objects from changes due to the
quasar itself, which might brighten and fade as
material swirls onto the accretion disc around its
central black hole.
The trick is to use a system like Q2237+0305,
where, thanks to lensing from a nearby galaxy, we
see four separate images of the quasar. If the quasar
itself is changing brightness, all four should be

Chris Lintott was reading… )UHHƆRDWLQJş3ODQHWVŝŝLQWKH0DFUROHQVHG
Quasar Q2237+0305 by Artem Tuntsov et al.
Read it online at: arxiv.org/abs/2401.05590

March 2024 BBC Sky at Night Magazine 15

The Sky at Night TV show, past, present and future

INSIDE THE SKY AT NIGHT

Production coordinator Rachael
Scott looks back on the last season
of The Sky at Night and tells us
what it takes for the TV show
to run smoothly

BBC X 7

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he year 2023 was the 66th year that
The Sky at Night has appeared on our
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as the show’s production coordinator.
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from London to Glasgow and the new team were
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at BBC Studios. Television was a completely new
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16 BBC Sky at Night Magazine March 2024

S Rachael’s
favourite episode
saw the show team
up with the popular
science podcast
The Infinite
Monkey Cage

At the start of each month, our talented editorial
team collaborated with our presenters to identify
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amateur astronomers to chat to. As production
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these individuals. Sometimes that meant organising
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space race. Other times it meant arranging travel to
the Very Large Telescopes in the Atacama Desert of
northern Chile. Every month came with new
challenges and new stories.
That series had eight monthly episodes, concluding
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collaboration with 7KH,QƅQLWH0RQNH\&DJH,W
included a large studio recording in the Radio Theatre
at London’s BBC Broadcasting House. Before the
recording, our presenters Chris Lintott, Maggie
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being together can be less common and it was lovely
to see them all catch up with one another. We also
squeezed in some rehearsal time with 7KH,QƅQLWH
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INSIDE THE SKY AT NIGHT
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presenters’ time together was short but sweet, with
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amateur astronomers in Leicester, at one of the
long-standing Sky at Night star parties. One tradition
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frequency of rain and cloud cover on these star party
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in-depth footage of the Moon’s craters. Party guests
included members of Leicester Astronomical Society

Rachael Scott is
a production
coordinator in the
BBC Studios Science
Unit and worked on
the 2023 series of
The Sky at Night

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spirits, fuelled by numerous cups of hot chocolate. All
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techniques with each other to identify the wonderous
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and historic this show really is.
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scenes and such a talented group of presenters on
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Looking back:
The Sky at Night
15 March 1980
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On the 15 March
and with no modern
1980 episode of The
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the guide scope to
of the heroes of his
ensure the telescope
youth, Clyde
stayed on target.
Tombaugh, who
Once the images
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were developed, he
Pluto 50 years
would compare
previously in 1930.
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An amateur
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discoverer Clyde Tombaugh
sequential nights,
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Explore the In Our Time archive
The BBC Radio 4 programme In Our Time,
hosted by Melvin Bragg, celebrated its
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episode of the show in the BBC Sounds
archive, many of which cover topics in space
and astronomy, including the planets Venus,
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and Caroline Herschel. Past episodes also
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Visit www.bbc.co.uk/sounds for more
information

S Melvin Bragg and his guests on In Our
Time discuss a range of topics, with several
episodes tackling space and astronomy

March 2024 BBC Sky at Night Magazine 17

Emails – Letters – Tweets – Facebook – Instagram – Kit questions

Email us at inbox@skyatnightmagazine.com
This month’s top prize:

two Philip’s titles

The ‘Message
of the Month’
writer will
receive a bundle
of two top titles courtesy
of astronomy publisher
Philip’s: Nigel Henbest’s
Stargazing 2024 and Robin
Scagell’s Guide to the
Northern Constellations
Winner’s details will be passed on to
Octopus Publishing to fulfil the prize

Meet the stars
I’m an astrophysics student at the University
of Leicester and Chief Astronomer of the
University of Leicester Astronomy and Rocketry
Society. I organise the society’s stargazing and
observatory activities at the Oadby
Observatory. In October we had the opportunity
to attend a star party there that was being
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were observing Jupiter through the Oadby
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Tweet
JUPITER IMAGE: EDWARD SMITH, SCOPE DOCTOR IMAGE: WWW.ALTAIRASTRO.COM

MESSAGE
OF THE
MONTH

Alan Crossland
#DODQŤ-DQXDU\
Orion rising over the Cuckmere
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#southdowns #Astrophotography
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S Left: the mystery dark smudge. Right: Luke

(left) meets The Sky at Night filming team

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moon of Jupiter, or from the secondary mirror,
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Luke Morriss, Leicester
What kind words, Luke! As for the feature you
saw on Jupiter, we wonder if it was a dark storm,
where a gap in higher clouds reveals the darker
cloud layer below. – Ed.

Glynis’s
painting of
the drama

Malvern fireball
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18 BBC Sky at Night Magazine March 2024

southwest path, and I imagined it
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SCOPE DOCTOR
Our equipment specialist cures your
optical ailments and technical maladies
With Steve Richards
Nicholas’s
sketch of
the solar
eruption

drawing shows the action,
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ON FACEBOOK
We posted an article by Maggie Aderin-Pocock entitled
‘Why I’m convinced there is alien life in the Universe’ (you can
read Maggie’s article at bit.ly/alien-life-universe). You had
your say in the comments section:
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I want to get started in astrophotography with
my Nikon DSLR and Sky-Watcher Startravel 120
AZ3 telescope. What settings should I use?
LEONARD CROOT

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Steve’s top tip
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DGYDQWDJHVRIDPRQRDVWURFDPHUDWRFRORXUFDPHUDXVHUV

Steve Richards is a keen astro imager and an
astronomy equipment expert

March 2024 BBC Sky at Night Magazine 19

INTERACTIVE
BBC Sky at Night Magazine is published by Our Media Ltd
under licence from BBC Studios, which helps fund new
BBC programmes.

EDITORIAL
Editor Chris Bramley
Content Editor Iain Todd
Features Editor Ezzy Pearson
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CONTRIBUTORS
Kerem Asfuroglu, Melissa Brobby, Anita Chandran,
Harry Cliff, Paul Fisher Cockburn, Charlotte Daniels,
Lewis Dartnell, Glenn Dawes, Russell Deeks, Mark
Garlick, Tim Jardine, Pete Lawrence, Chris Lintott,
Mary McIntyre, Laura Nuttall, Jonathan Powell, Katrin
Raynor, Steve Richards, Govert Schilling, Rachael
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Martin Smith, Executive Editor, BBC Radio Science Unit;
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Dr Erica McAlister

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20 BBC Sky at Night Magazine March 2024

X

much nearer to the Big Bang. Surely
we should not be surprised to see them
travelling faster?
Tom Jones, via email

Time check
I notice that in the astrophotography
Gallery section of the magazine, those
photographers featured use abbreviations
to denote exposure length, notably ’ and ”.
I assume these are probably second and
minute and I’d like to know for sure. I’ve
VHDUFKHGWKHZHEDQGFDQŝWƅQGD
GHƅQLWLRQIRUWKHP&RXOG\RXLQGLFDWH
your interpretation of the correct symbols
for second, minute and hour with regard
to astrophotography exposure times?
Michael Spoors, Alton, Hampshire

Instagram
urban.astrophotography •
14 January
The iconic Horsehead Nebula
meets Andy Warhol’s palette in cosmic
Technicolor. Tech details: Astro Tech
AT115EDT 4.5-inch triplet refractor at
f/5.6, EQ6-R mount, NINA, ASI 1600MM
3URFDPHUD&KURPD6+2ƅOWHUV
processed in PixInsight, 2.5h Ha,
1.5h OIII, 2h SII, Bortle 9.

That’s correct, Michael: a single apostrophe
(’) indicates minutes and a double
apostrophe (”) seconds. We also use h
to indicate hours. – Ed.

Flare theory
I just spotted the photo that Mike Nold
sent of the Moon halo (‘Space oddity’,
Interactive, February 2024 issue). The
offset nature of the halo suggests to me
WKDWLWŝVPRUHOLNHO\DOHQVƆDUHDVRSSRVHG
to anything natural. If it was due to ice
crystals it would be central around the
Moon, and he’d have seen it at the time.
If Mike still has the camera and lens, he

may be able to reproduce the effect by
positioning a bright light at the same
position in the frame. This could be done
with a modern mirrorless camera and a
cheap adaptor to mount the lens, rather
WKDQZDVWLQJDUROORIPPƅOP
James Billings, via email

SOCIETY IN FOCUS
Kernow Astronomers is a friendly
group sharing a common interest in all
things astronomical. Our membership
ranges from complete beginners to
those experienced in observing and
astrophotography.
Our meetings cover most areas of
astronomy, mainly via visitor talks, our
own members’ presentations and group
discussions. Members from the local area
and wider west Cornwall meet on the third
Thursday of the month throughout the
year, in the village of Summercourt, an
ideal mid-Cornwall location easily
accessed from the main A30 route
through the county. Practical observing
meetings are held from October to March
at Trevarrian, north of Newquay on the
north coast.
We’re keen to spread enthusiasm for the
wonders of the Universe to everyone,
young and old. We run regular star parties

S Kernow Astronomers at a local school
for a summer solstice solar observing day

and open evenings, while individual
members also give talks to local schools
and other groups, and write articles in the
local press. We stage events with the
National Trust, such as our regular ‘Sun
and Stars’ evenings at the Dark Sky
Discovery Site, Carnewas, on the north
Cornwall coast, and at Trerice. A recent
event there drew 400 visitors excited to
observe all things celestial through our
telescopes and solar scopes.
*O\QQ%HQQDOOLFN3XEOLFLW\2IƅFHU
X www.kernowastronomers.com

We pick the best live and virtual astronomy events and resources this month

,

PICK OF THE MONTH

Spring Star Party
Kelling Heath Holiday Park,
Holt, Norfolk, 5–12 March
One of Britain’s best-known star parties
returns. A strict no-lights policy is in force,
making it the ideal place to meet up with
fellow astronomers and enjoy the delights
of the night sky. Plus: red squirrels! Prices
start at £26.52 per night for a camping
pitch, with more luxurious lodges starting
at £350 for three nights.
www.kellingheath.co.uk

S The Practical Astronomy Show moves to a bigger venue for 2024, but is still free

An Evening of Astrophotography

The Practical Astronomy Show 2024

Royal Observatory, Greenwich,
8 March, 6pm
International Women’s Day sees an
after-hours panel discussion highlighting
and celebrating the work of women in
astrophotography, with guests including
judges from the Astronomy Photographer
of the Year competition. Tickets cost £12,
concessions £8.50.
www.rmg.co.uk

National Agricultural and Exhibition Centre, Coventry, 23 March

The annual gathering of the UK
astronomy industry returns, with the free
event having proven so popular that this
year it’s moved to a new, larger venue.
Exhibitors at this year’s show include the
Campaign for Dark Skies, the Society
for the History of Astronomy and the
UK Radio Astronomy Association, as
well as a host of astronomy equipment

manufacturers and retailers, many
of whom will be offering special
discounts for show visitors on the day.
Whether you’re in the market for a new
telescope or just hoping to pick up
some astrophotography tips, there’s
something for everyone – including an
on-site cafeteria, full disabled access and
free parking. practicalastroshow.com

Aberdeen’s Institute of Complex Systems
and Mathematical Biology discusses the
structural stability and long-term future
of the Solar System. Free for all attendees.
www.aberdeenastro.org.uk

take a virtual night-sky tour in their mobile
planetarium. Adults £25, ages 6–15 £20.
astro-dog.co.uk

KELLING HEATH, © 2024 PRACTICAL ASTRONOMY SHOW X 4

Tuning in to Primordial Stars
Astronomy Ireland, via Zoom,
11 March, 7pm
The University of Nottingham’s Dr Emma
Whelan presents a live-streamed lecture
VXEWLWOHGŜ6HHLQJƅUVWOLJKWZLWKUDGLR
telescopes and JWST’. You’ll need to
register online in advance, at a cost of €5
for members or €10 for non-members.
astronomy.ie

Stability of the Solar System
and Chaos
Robert Gordon’s College, Aberdeen
and online, 12 March, 7pm
Dr Nicolas Rubido from the University of

Stargazing with Astro Dog
Dalby Forest, North Yorkshire,
every Thursday/Friday/Saturday, 8pm
View the stars through some seriously
powerful telescopes at one of Astro
Dog’s regular public astronomy
events in the Dalby Forest. Get expert
astrophotography tips or, if it’s raining,

BAA meeting
Institute of Physics, Caledonian Road,
London, 27 March, 5pm
The British Astronomical Association
returns to the Institute of Physics for its
quarterly meeting, with talks on Mars,
Jupiter and more. BAA membership is
open to all amateur astronomers and
costs £53.50 per year (concessions from
£12.50). britastro.org
March 2024 BBC Sky at Night Magazine 21

The Books that Unlocked
the Mysteries of the Universe

By Karen Masters – Astronomy and Physics
Professor at Haverford College, Philadelphia.
PUBLISHED 25TH APRIL 2024
Pre-order online or from your local bookshop NOW
ISBN 978 0711289819

The astronomer’s forum

The expanding Universe of the mind

A

Jonathan Powell is
a freelance writer
and broadcaster.
A former
correspondent at
BBC Radio Wales,
he is currently
astronomy
columnist at the
South Wales Argus

s a species, the gradual unveiling
of the mysteries of the Universe has
only been achieved through the
results of our own innovation, unaided
and unassisted by anyone else. From
early cave paintings that captured the heavens, to
tracking the motions of stars and planets to form
basic calendars, to agricultural usage, with the
planting and reaping of crops. Soon, though, instead
of just observing the points of light in the night sky,
great minds such as Ptolemy, Copernicus and Kepler
turned to attempts at explaining them.
Landmark timeline events serve as poignant
reminders of the parallel relationship between the
human mind and the Universe. Galileo’s telescopic
sketching of Saturn in the early 1600s, and in
particular that of the planet’s rings, were humankind’s
ŜƅUVWOLJKWŝRQDQREMHFWWKDWKDGEHHQZDLWLQJELOOLRQV
RI\HDUVIRUWHFKQRORJ\RQ(DUWKWRVXIƅFLHQWO\
advance in order to make such an observation.

Galileo’s puzzlement over what he saw as Saturn’s
‘arms’ was duly solved, as the optical revolution of the
time allowed Dutch astronomer Christiaan Huygens
to declare in 1659 that those ‘arms’ were in fact rings.
$V*DOLOHRRSHQHGWKDWƅUVWGRRU+X\JHQVRSHQHG
the second, and the momentum continued as the
centuries passed, eventually leading to the Pioneer,
Voyager and Cassini–Huygens missions.
Environmental philosopher John Muir (1838–1914),
wrote that “the clearest way into the Universe is
through a forest wilderness”. Just as a torch beam
illuminates the interior of a cave as the explorer
ventures deeper into its labyrinth, the path towards
our own understanding is one revealed a step at a
time. Those shafts of light through the forest canopy
to the ground have not only produced discoveries
upon our journey, but enhancements of phenomena
that have already been captured lightyears distant,
as the James Webb Space Telescope impressively
sharpened the Hubble Space Telescope’s image of
the Pillars of Creation.
Perhaps more remarkably, Albert Einstein’s theory
of relativity, which predicted the existence of what
American physicist John Wheeler later coined ‘black
holes’, has now been presented to us in an image,
thanks to the Event Horizon Telescope. It’s proof that
at times we are perhaps ahead of the Universe in
our thinking, but never naive enough to believe until
proven that one’s theory is correct.
As we look at the Universe, let us not forget that,
in its own way, it has also been looking back at us.
One of its emissaries (‘Oumuamua aside), is Halley’s
Comet. With every periodic sweep of its body and
tail, this comet has witnessed an ever-changing shop
window of the life on planet Earth. With each pass
there have been different residents looking skyward
at the comet, using different means to observe it and
with different thoughts to explain it.
Recent studies suggest that the Universe is
expanding faster than previously understood, but
given our astronomical accomplishments, and maybe
PRUHVRRXUGHYHORSPHQWVLQVSDFHƆLJKWWHFKQRORJ\
it would more than indicate that we remain closely
aligned in both mind and capability with the
accelerating expansion of the Universe.
March 2024 BBC Sky at Night Magazine 23

STEPHAN SCHMITZ/FOLIO

Jonathan Powell reflects on where our finite understanding meets infinite space

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ESO/L. CALÇADA/M. KORNMESSER

ILLUSTRATION

It’s elemental: the lives of stars,
or rather their cataclysmic
deaths, spawned all the ‘stuff’
in the Universe – including us

26 BBC Sky at Night Magazine March 2024

It’s said that we’re all made of star stuff, but how is
that star stuff itself made? Harry Cliff explains

E

verything we can see
in the world around
us is made of atoms.
But where did those
atoms come from?
It’s a question that’s fascinated
natural philosophers and scientists
for centuries, and is one we’re still

learning more about today.
At the start of the 18th century,
Isaac Newton declared that atoms
had probably been created by
God at the beginning of time.
He believed that atoms were
indestructible, “no ordinary power
being able to divide what God had

PDGHRQHLQWKHƅUVWFUHDWLRQŠ
+RZHYHULQWKHƅUVWGHFDGHVRI
the 20th century, physicists found
that they could break atoms apart
in the lab using powerful, albeit
earthly, forces, which eventually
led to the realisation that every
atom in the periodic table is made X

March 2024 BBC Sky at Night Magazine 27

X

of just three subatomic particles: electrons,
protons and neutrons.
The discovery of atomic substructure opened up
the possibility that atoms themselves had been
created out of these basic constituents. But how?
Every atom has the same structure, a tiny
positively charged nucleus orbited by negatively
charged electrons. The nucleus itself is made of
positively charged protons and electrically neutral
neutrons bound together by the strong nuclear
force, and crucially it is the number of protons in the
nucleus that determines whether an atom is, say,
carbon, oxygen or uranium.

Hydrogen is the simplest atom, a single proton
orbited by a single electron, and most of the
hydrogen we see in the Universe today was
created shortly after the Big Bang. It
is the obvious candidate for the
raw material from which all the
heavier elements are made.
The next simplest atom is
helium, whose nucleus is
made of two protons
and two neutrons.
However, combining
hydrogen together
to make helium is
far from easy.
Protons are
positively charged,
and so exert an
enormous repulsive
force on each other
when they come
close together. For
two protons to fuse,
they have to get within
around 10 -15 metres of
each other – a distance
comparable to the size of the
protons themselves – at which
point the attractive strong nuclear
force begins to overcome their electrical
repulsion. However, to get two protons this
close they have to be moving incredibly quickly,
fast enough to zip up the steeply rising electrical
barrier that keeps them apart. This means that for
hydrogen to undergo nuclear fusion it has to be
very, very hot indeed, with a temperature of at least
several million degrees.
Where in the cosmos can such extreme conditions
be found? One answer is, in the interiors of stars.
ILLUSTRATION

EMILIJA RANDJELOVIC/ISTOCK/GETTY IMAGES, FAMBROS/ISTOCK/GETTY IMAGES,NASA/CXC/M. WEISS, BSIP/GETTY,
XRAY: NASA/CXC/SAO/OPTICAL: NASA/STSCL/INFRARED: NASA/JPLCALTECH/STEWARD/O.KRAUSE ET AL

Raw materials

28 BBC Sky at Night Magazine March 2024

S Stars fuse
hydrogen into
helium in their
furnace-like cores,
keeping the stars
shining – until the
fuel runs out

Take, for example, the Sun. At its centre, the
crushing gravity of our local star’s mass heats the
core to a blistering 15 million degrees, allowing
hydrogen nuclei (protons) to fuse together
to produce helium. However, since
you need two protons and two
neutrons to make helium, this
doesn’t happen in a single
reaction but in a stepH
by-step process known
as the ‘proton–proton
chain’, whereby a
He
helium nucleus is built
O,
up through a series
C
O,
of nuclear collisions,
Ne,
Si,
accompanied by
S Mg
the occasional
Fe
conversion of a
proton into
a neutron.
Not only do
these nuclear fusion
reactions produce
helium, they also
generate the energy
that keeps our local star
shining and stops
it collapsing under its
own gravity.
The Sun will carry on merrily
fusing hydrogen into helium for another
ƅYHELOOLRQ\HDUVEXWHYHQWXDOO\WKHK\GURJHQ
needed to fuel its nuclear furnace will run out. At
S A simplified view
that
point, things will get rather interesting for
of the distribution
anyone still living in the inner Solar System.
of elements in a
Without a source of energy to counterbalance
core-collapsing star
before it explodes
gravity, the Sun’s core will start to collapse and heat
up. Eventually, it will become so hot that hydrogen
fusion will re-ignite, but this time in a spherical shell
surrounding the helium-rich core. Previously, this layer

It began with a bang
The amount of hydrogen and helium in the Universe was set after the Big Bang
However, about three minutes in,
the Universe had expanded and cooled
to a few billion degrees. The photons
no longer had enough energy to break
nuclei apart. Suddenly, nuclear fusion
could get going, and a blizzard of
collisions rapidly converted protons
and neutrons into helium.
After about 100 seconds, all the free
neutrons had been gobbled up and the
amount of helium in the Universe was
essentially set.

7RGD\SK\VLFLVWVƅQGWKH%LJ%DQJ
theory predicts around 25 per cent of the
Universe by mass should be helium, with
the rest made up of hydrogen and a tiny
sprinkling of lithium. This is more or less
precisely what we see in the Universe
today and is one of the strongest pieces
of evidence that our Universe really did
begin with a bang.

Within minutes of the Big Bang,
the Universe cooled enough to
IRUPWKHƅUVWHOHPHQWV

ILLUSTRATION

Though stars have acted as cosmic
factories, gradually enriching the
Universe with heavy elements for the
last 13.7 billion years, they cannot
account for the second-most common
element of all: helium.
Stars do indeed make helium, but
nowhere near enough to explain the fact
that helium makes up a quarter of the
atoms in the Universe by mass.
To understand helium’s origin, we must
look to the greatest cosmic forge of all:
WKH%LJ%DQJ'XULQJLWVƅUVWIHZPLQXWHV
WKH8QLYHUVHZDVƅOOHGE\DVHDULQJ
plasma with roughly equal numbers of
protons and neutrons, ideal conditions,
you might think, for the formation of
elements beyond hydrogen. However,
up until about three minutes after the
Big Bang, there were so many highenergy photons (particles of light) zipping
about that any nuclei that formed were
immediately blasted apart again by a
collision with a photon.

was too cool for fusion to take place.
The restart of fusion will release a new blaze of
OLJKWLQWRWKHXSSHUUHJLRQVRIWKHVWDULQƆDWLQJLW
to become a monstrous red giant between 100 and
200 times its current diameter, so large that it will
consume the inner planets, likely including Earth.

Death throes
Meanwhile, deep inside the red giant, the core will
continue to shrink and heat up, eventually reaching
a searing 100 million degrees. This is hot enough to
allow even larger atoms to combine, igniting helium
fusion into carbon, and then carbon–helium fusion to
make oxygen. When this happens, the Sun will shrink
back down to a yellowish star, around 10 times its
current size. However, this new age of helium fusion
will be brief in solar terms, a mere 100 million years,
after which the core will resume its inward collapse.
,QLWVƅQDOJDVSVPL[LQJEHWZHHQWKHVWDUŝVLQQHU
layers will result in the fusion of carbon and hydrogen
to make nitrogen, until at last, the Sun will gently
puff its atmosphere out into space, enriching the
surrounding galactic medium in carbon and nitrogen.
At the centre of this expanding cloud of luminous gas
will be all that remains of the solar core, a glowing
husk about the size of Earth: a white dwarf.
The majority of the carbon and nitrogen in our
bodies came from the deaths of small, yellow stars

S Inside out:
dead stars like
Cas A scatter their
elements (like the
iron core shown
here in green),
seeding life across
the Universe

like our Sun. However, for heavier elements, we must
look to even more dramatic stellar events.
While our Sun will die with something of a whimper,
larger stars go out with a bang. The nuclear career
of a star more than eight times the mass of the Sun
doesn’t end when its core is converted into carbon
and oxygen. Instead, its enormous gravity heats
the core to over a billion degrees – hot enough to X
March 2024 BBC Sky at Night Magazine 29

ILLUSTRATION

“The resulting
stellar explosion,
known as a Type II
supernova,
can briefly
outshine all the
stars in a galaxy”

KEVRON2001 ISTOCK/GETTY IMAGES, ESO, ELIZABETH WHEATLEY (STSCI),
NASA’S GODDARD SPACE FLIGHT CENTER CONCEPTUAL IMAGE LAB

X

force carbon nuclei together to make even
heavier elements, including neon, magnesium
and sodium.
When the carbon runs out – after
DSLIƆLQJ\HDUVŚWKHVWDU
undergoes a further series of
collapses, heating up and igniting
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GD\WKHFRUHUHDFKHVELOOLRQ
degrees, hot enough to trigger
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burning of silicon to make iron
and nickel.
Iron and nickel are the most
stable elements in the periodic
table, and so fusing them to
make even heavier elements
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releasing it. This means that once the
core has been converted into iron and nickel,
the star has twinkled its last. With no further
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the star implodes, crushing the core into such a
VPDOOYROXPHWKDWLWUHDFKHVWKHVDPHGHQVLW\DVDQ
atomic nucleus. At this point the strong nuclear force
ƅJKWVEDFNDJDLQVWJUDYLW\DQGWKHLQIDOOLQJEXONRI
WKHVWDUHIIHFWLYHO\ERXQFHVRIIWKHFRUHFUHDWLQJD
shockwave that rips the star apart from the inside
DQGVHQGVDFDWDFO\VPLFEODVWRIOLJKWDQGPDWWHU
out into space: a supernova. Meanwhile, the core
30 BBC Sky at Night Magazine March 2024

SN1987a

S Supernova 1987A,
one of the brightest
supernovae seen in
400 years, blazed
for months in 1987

itself collapses into a single, giant atomic nucleus
PDGHHQWLUHO\RIQHXWURQVŚDQHXWURQVWDUŚ
RULILWLVKHDY\HQRXJKDEODFNKROH
The resulting stellar explosion,
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LQDJDOD[\,QWKHIHURFLRXV
conditions inside the supernova,
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iron and nickel are created as
lighter nuclei are bombarded
E\DQLQWHQVHZDYHRIIUHH
neutrons, resulting in elements
including gallium, germanium,
EURPLQHDQGNU\SWRQ$WWKH
same time, particles accelerated
to close to the speed of light tear
through larger nuclei like bullets,
breaking them apart to form much
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7KHVHQHZO\PLQWHGQXFOHLDUHEODVWHG
out into the Universe, along with products of
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magnesium and iron, enriching the cosmos with a
KHDG\HOHPHQWDOFRFNWDLO

Gold flingers
Perhaps the most exciting recent advance in our
XQGHUVWDQGLQJRIWKHRULJLQRIDWRPVFDPHLQ
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*UDYLWDWLRQDO:DYH2EVHUYDWRU\ /,*2 RI

Harry Cliff is a particle
physicist at Cambridge working
on the Large Hadron Collider
and the author of Space
Oddities (2024)

ILLUSTRATION

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two neutron stars. Along with the gravitational wave,
observatories around the world detected light from
the awesome collision, revealing large quantities of
precious metals, including platinum and gold. In fact,
E\RQHHVWLPDWHWKHQHXWURQVWDUFROOLVLRQSURGXFHG
HQRXJKJROGWRPDNHVROLGJROGSODQHW(DUWKV
2IFRXUVHWKLVJROGLVQŝWƆRDWLQJWKURXJKVSDFHLQ
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the other elements come together to form new stars.
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to form the planets.
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WKHGHDWKVRIVWDUVELOOLRQVRI\HDUVLQWKHSDVW

Colliding dead (neutron) stars
have been detected creating
planets’ worth of gold

Small stars, big elements
While we’ve explained the main routes
through which the elements are made,
the full story of their origin is incredibly
intricate. Sometimes a smaller star can
create elements much heavier than it
normally would through fusion alone.
In one rare case, white dwarfs – the
end state of low-mass stars like our
Sun – actually gain enough mass to go
supernova. This happens when they’re

close enough to a companion star that
they gradually steal matter from it. The
matter falls onto the surface of the white
dwarf until its mass becomes so high
that nuclear fusion restarts, violently
detonating the white dwarf in a Type 1a
supernova. This produces large amounts
of elements like sulphur, iron and copper.
It’s even possible for low-mass stars like
the Sun to create heavy elements beyond

iron, despite not being large enough to
fuse elements heavier than carbon and
oxygen. This is because although mostly
composed of hydrogen when they form,
stars contain some of the heavy nuclei
inherited from earlier generations of
stars. Neutrons released in the stars’
fusion reactions can be captured by
these heavy nuclei, converting them
into even heavier elements.

Some white dwarfs are
rekindled after siphoning
matter from nearby stars

March 2024 BBC Sky at Night Magazine 31

ILLUSTRATION

Under certain conditions, stars like the Sun can create heavy elements as well

The fundamentals of astronomy for beginners

E XTRA

Aurorae and solar maximum

SUMOS/ISTOCK/GETTY IMAGES, TTSZ/ISTOCK/GETTY IMAGES,
NASA’S GODDARD SPACE FLIGHT CENTER/MARY PAT HRYBYK
KEITH, SOHO (ESA & NASA)

We could be in for some incredible aurora displays
as the Sun’s magnetic activity is due to peak this year

A

urorae are one of nature’s most beautiful
spectacles, but also one of the most
elusive. For aurora hunters, some
nights will yield little more than a green
smudge on the horizon, others nothing
at all. But then will come the nights when the air will
burst into life as light dances across the sky.
There are no guarantees when it comes to seeing
aurorae, but you might be able to stack the odds
in your favour. The next few years are going to be
some of the best for those hoping to catch the
lights, as our Sun is currently approaching a time of
intense activity, known as solar maximum. Scientists
watching the Sun predict this could happen in 2024.

32 BBC Sky at Night Magazine March 2024

S With Solar
Cycle 25 said to
now be at or near
its peak, more and
more people are
getting to tick ‘See
the Northern Lights’
off their bucket lists

To understand why, we must travel to the aurorae’s
beginnings on the surface of the Sun. Our star emits
a constant stream of charged particles, known as the
solar wind, that traverses through the Solar System
at huge speeds.
This wind then eventually collides with our planet,
or rather the protective bubble created by Earth’s
PDJQHWLFƅHOGDURXQGWKHSODQHWNQRZQDVWKH
PDJQHWRVSKHUH0DJQHWLFƅHOGVFDQVNHZWKHSDWK
of charged particles, changing their motions so that
WKH\PRYHDORQJLWVƅHOGOLQHV$VVXFKWKHVRODU
ZLQGLVGHƆHFWHGDURXQGWKHPDJQHWRVSKHUHVRWKDW
most of it passes safely around the outside, like water
ƆRZLQJSDVWDURFNLQDVWUHDP

Solar wind

6RODUƆDUH

(DUWKŝVPDJQHWLFƅHOG

S Flares fired our way are generally seen off by Earth’s magnetic field – but some solar particles sneak into our magnetosphere

Some of the particles, however, are able to sneak
through into our magnetosphere. Once inside, they
EHFRPHFDXJKWLQƅHOGOLQHVWKDWJXLGHWKHPGRZQ
towards the planet. These solar particles, along
with others that were previously trapped within
our planet’s radiation belts, are then accelerated
down towards the surface by Earth’s magnetic
ƅHOG)RUPLQJDULQJDURXQGWKHQRUWKDQGVRXWK
poles, known as the auroral oval, the particles
keep travelling until they hit molecules in Earth’s
atmosphere. This transfers some of the accelerated
particles’ energy, causing the atmospheric molecules
to glow. The altitude and the type of molecules they
hit determine the colour of the glow. The aurorae’s
famous green hues come from oxygen molecules
at an altitude of 100–240km. The less common reds
originate from oxygen above 240km, while the rarely
seen blues are created by nitrogen under 100km.
:KHQDƆXUU\RIFKDUJHGSDUWLFOHVERPEDUGWKH
atmosphere at once, the glow is great enough
for human eyes to pick up. This is when the
aurorae dance before our eyes.

Far from predictable
Precisely how aurorae work is still
being discovered, but one thing that’s
clear is that the more active the Sun
is, the more likely it is that spectacular
aurorae will arise. Not only that, but
if the solar wind is blowing faster, the
more energy the particles have. This
makes the auroral oval larger, pushing it
closer to the equator, meaning the lights
can be seen over a much larger area.
For this reason, dedicated aurora hunters

The kaleidoscope
of colours we see at
different altitudes

400km
Ionosphere

Thermosphere

240km

100km
Mesosphere
Stratosphere

Not to scale

Troposphere

watch for times when the Sun is more active. One
event to particularly keep an eye on are coronal
mass ejections (CMEs), where the Sun’s twisting
PDJQHWLFƅHOGƆLQJVDEORERILWVRZQVWHOODU
material out into space. It’s possible to
get some warning that a CME is about
WRFROOLGHZLWK(DUWKWKDQNVWR1$6$ŝV
Solar and Heliospheric Observatory
(SOHO), which monitors the Sun’s
activity in real time, looking for the solar
ƆDUHVWKDWXVXDOO\KHUDOGDQLQFRPLQJ
CME. Currently, however, there’s no way
to predict when a CME is going to erupt. X
W An Earth-directed coronal mass ejection

can send high-energy solar winds towards our
planet, sparking dazzling light shows days later

March 2024 BBC Sky at Night Magazine 33

The shape of the aurora

MARKUS VARIK/HTTPS://GREENLANDER.NO/WWW.INSTAGRAM.COM/GREENLANDER_TROMSO/WWW.FACEBOOK.
COM/GREENLANDERTROMSO, EERIK/ISTOCK/GETTY IMAGES, NASA’S SOLAR DYNAMICS OBSERVATORY/JOY NG,
NASA/GSFC/SDO, ALEX RAMSAY/ALAMY STOCK PHOTO

The lights take on many forms across the night sky

Patches

Arcs

More diffuse than
other displays,
these blobs of light
tend to spread out
across the sky.

Many displays begin
as a curve of bright
light across the sky,
known as an arc, before
transforming into more
complex shapes.

Coronae

Curtains

Bands

Rays

Created from rays
of light moving
together in bands,
viewed from a
distance these
sweeping forms
resemble a set of
hanging curtains.

Similar to arcs,
bands tend to have
a more undulating
appearance to
their lower border,
creating a snaking
glow across the sky.

These shafts
of light stretch
upwards into the
sky and during
more active
displays can even
appear to pulse
and move.

Meaning crown,
coronae are
large starburst
formations. They
FDQEHGLIƅFXOWWR
catch, however,
as you’ll only
see such a view
if you’re directly
underneath it.

X It is, however, possible to say when it’s more likely
for such events to occur. The Sun goes through an
approximate 11-year sequence of rising and falling
activity, known as the solar cycle, which solar
scientists track by measuring the number of sunspots
on the solar surface. Each cycle begins with a solar
minimum; at these times it could be months, or even
years between one sunspot and the next. Then, over
several years the number of sunspots increases until
they reach a peak, known as the solar maximum.
After this, the sunspot numbers trail off once more to
a new minimum and the start of a new cycle.

Are we at the peak?
Though the cycle tracks sunspots, the rise and fall of
other activity of the Sun follows alongside, including
CMEs, which usually reach a peak in the years just
after solar maximum.
We are currently in Solar Cycle 25, which started
in December 2019, so-named because it is the 25th
since records began. Initial predictions put the
maximum in mid 2025 and forecast that it would be
one of the weakest cycles, with low sunspot numbers.
As the cycle has gone on, however, it’s quickly
34 BBC Sky at Night Magazine March 2024

Solar maximum, 2014

S Look lively:

sunspots flare
dramatically at
peak times,
which is where
we (probably)
are now

Solar minimum, 2019

become clear that those predictions were not correct.
The actual number of sunspots is much higher than
forecast, and the date of solar maximum has now
been revised to sometime between January and
October 2024. That means it could be the peak of
solar activity right now, although we won’t know for
sure exactly when the peak occurs until after it has
passed and activity begins to fall again.

We won’t know exactly how active Solar Cycle 25
will be until then, but it’s already shaping up to have a
higher peak than the previous solar cycle, Solar Cycle
24. And it’s already begun to show in the aurorae.
,QWKHUHZHUH;FODVVVRODUƆDUHVŚWKH
PRVWSRZHUIXORIWKHLUNLQGŚVHYHUDORIZKLFKZHUH
accompanied by CMEs. The Northern Lights were
seen as far south as West Wales and Cornwall in the
UK, while a photographer was able to capture them
over Death Valley, California in the US. Meanwhile,
their Southern Hemisphere counterparts, the
Southern Lights, have been making rare appearances
above mainland Australia and New Zealand.
Getting to witness an aurora display always
involves an element of chance. But if you’ve always
wanted to get out and see the Northern Lights dance
DFURVVWKHQLJKWVN\WKHQH[WIHZ\HDUVZLOOGHƅQLWHO\
give you the best chance of catching the show.

Huge X-class solar
ƆDUHVDUHRQWKHXS
– a trigger for intense
aurora displays

Southerly places
like Knighton in mid
Wales have been
treated to the lights

Ezzy Pearson is BBC Sky at
Night Magazine’s features editor.
Her book Robots in Space is
available through History Press

How to catch an
aurora display
Finding the right time and place is the key
when tracking down the Northern Lights
Aurora displays can show up at any
WLPHDIWHUGDUNEXWWKHUHDUHGHƅQLWHO\
times when an aurora sighting is more
likely, whether it’s near solar maximum
or not.
As aurorae are most visible against
dark skies, it’s best to hunt for them in
spring, autumn and winter, when the
nights are longer. For an even better
chance, stick to the months around
the equinoxes: March and April,
September and October. During this
WLPH(DUWKŝVPDJQHWLFƅHOGLVEHVW
orientated to the solar wind, and more
likely to create the interactions needed
to produce the lights.
The best place to see the Northern
Lights is in the auroral oval. In the
Northern Hemisphere, the oval sits at a
latitude around 65°N to 70°N, covering
the northern regions of Finland,

Sweden, Norway
and Canada, as
well as Iceland and
Alaska. These are
all popular sites for
aurora hunters.
Those located a
little further south would
do well to keep an eye
on aurorae forecasting apps
and websites, however, to see if a
particularly energetic CME is on its way.
This can push the oval to more southerly
latitudes and it’s not uncommon for
the lights to appear above Scotland. A
particularly strong solar storm will move
the oval even further south than that.
Whether you’ve travelled to see the
aurorae or they have come to you, the
faint lights are best viewed from a dark
site as far away from light pollution as

Geographic pole

Geomagnetic pole

65º
70º
75º

S Go north: the auroral oval at the north

magnetic pole, where solar particles hit
Earth’s atmosphere, is the aurora hotspot

possible. They can appear at any
time, but the best views are usually
between 10pm and 2am. Once you’re
in position, it’s just a case of watching
and waiting for the lights to begin
forming on the sky.

March 2024 BBC Sky at Night Magazine 35

Lighting designer
Kerem Asfuroglu
explains how
considerate lighting
has helped three
communities to
protect their dark skies

DYLAN PARRY EVANS & TUDUR EVANS

T

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36 BBC Sky at Night Magazine March 2024

for the

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DQGIRUWKHSHRSOHZKROLYHLQWKHP X

Plas y Brenin outdoor centre,
one of the sites transformed by
dark-sky-friendly measures

March 2024 BBC Sky at Night Magazine 37

Before

After

Before

After

S Streets in the centre of Presteigne, before and after the lighting improvements. The scheme installed hundreds of warm-white LED

luminaires on timers in place of glaring cool-white LEDs, winning the community Dark Sky accreditation at the start of this year

LEIGH HARLINGBOWEN & KEREM ASFUROGLU, LEIGH HARLINGBOWEN, GEORGIA MACMILLAN X 2

Presteigne & Norton Dark Sky Community,
Powys, Wales
This project gained the recognition of
DarkSky International in January 2024,
E\EHFRPLQJWKHƅUVW'DUN6N\
Community in Wales. This achievement is
also a product of a unique collaboration
that brought together the local
community, Presteigne & Norton Town
Council and Powys County Council.
Covering an outer area of 40km2 and
a combined population of 2,700, the
historic Radnorshire towns of Presteigne
and Norton are located on the border with
England, in Powys, Wales’s largest county.
In contrast to other areas of the UK,
more than 18 per cent of Wales has been
assigned dark-sky status. Precedents like
this project are important, as they pave
the road for bigger and more populated
settlements to challenge the norms in
order to become dark-sky-friendly.

In developing environmentally friendly
lighting for the residents, a judicious
lighting approach has been essential. In
Presteigne and Norton’s case, the street
lighting was the main layer of illumination
causing problems. Orange-tinted sodium
lighting had been replaced with coolwhite LEDs (a colour temperature of
6,500K), which saved Powys County
&RXQFLODVLJQLƅFDQWDPRXQWRIPRQH\E\
reducing running costs. However, the bluerich colour of this LED light introduced
PRUHVLJQLƅFDQWOLJKWSROOXWLRQSUREOHPV
ƆRRGLQJWKHVWUHHWVZLWKUDGLDQFH
Frequent sky-quality monitoring and
engagement programmes organised by
the local community raised awareness,
which eventually ensured the protection
of a large area that is home to lightsensitive bat species and the nearby

Spaceguard Centre observatory. A total
of 380 lighting columns were refurbished
with warm-white LED luminaires
(lighting units, with a colour temperature
of 2,200K); about half of them were
programmed to switch off and the rest to
dim by 50 per cent after midnight.
Comprehensive lighting tests were
carried out and feedback was sought
from the wider community throughout
the project, which has reduced the town’s
annual carbon dioxide emissions by 4.5
tonnes. Its success has prompted the local
authorities to consider rolling out similar
lighting schemes across the county. This
will empower many other communities to
pursue dark-skies accreditation if they so
choose, an important ripple effect for the
continuity of dark skies across Wales and
the UK.

Before
S Looking back on Presteigne and Norton from a nearby hill, it’s clear how the new lighting scheme drastically reduced skyglow

38 BBC Sky at Night Magazine March 2024

After

of the church both by day and at night.
These lanterns are designed to provide
a warm colour temperature (2,200K) and
subtly illuminate the church periphery
without causing any glare. This has
encouraged the public to visit and
explore the church grounds after dark,
RYHUFRPLQJWKHGD]]OLQJƆRRGOLJKWVZKLFK
formerly inhibited movement.

A matter of emphasis
Attention was drawn to
ground features instead of
shining light into the sky

Newport, County Mayo, Ireland
Ireland has great potential to establish
several dark-sky areas, and these
possibilities have been adopted in
Newport, a town with ambitious
DVSLUDWLRQVWREHFRPHWKHƅUVWGDUN
sky community in Ireland. Located near
the Wild Nephin National Park, which
becomes Mayo Dark Sky Park after
nightfall, the town aims to establish an
important precedent in veering away from
UXUDOSUHFRQFHSWLRQVDQGFRQƅUPLQJWKDW
populated settlements can also become
valuable dark-sky destinations.
As part of this project, two local
architectural landmarks, St Patrick’s
Church and the Seven Arches Bridge, were
LGHQWLƅHGDVVLWHVZKHUHOLJKWLQJUHGHVLJQ
could eliminate the light pollution and
visual discomfort currently caused by their
poor illumination.
7KHƅUVWSKDVHRIWKHSURMHFWIRFXVHG
RQUHSODFLQJWKHJODULQJƆRRGOLJKWVFKHPH

Before

at St Patrick’s Church, which was lit by
luminaires that diminished the beautiful
heritage architecture of the 100-year-old
building. Visible from numerous points in
WKHWRZQLWVKLOOWRSORFDWLRQLQWHQVLƅHG
the adverse effects of the poor lighting,
with large quantities of wasted glare
ascending into the sky and failing to
bring out the ornamental features of the
church’s facade. The project sought not
only to change the lights one by one, but
also to futureproof the design.
The community grasped this as an
opportunity to change the relationship
between the church and its surroundings.
Before, vertical façade lighting had
shaped the visual emphasis when seeing
the church at night, and this was inverted
by instead putting the emphasis on the
horizontal ground plane. Next, lanterns
were reinstalled on the perimeter railings,
which has restored the heritage fabric

On the church itself, we explored the
potential of emphasising key architectural
elements by replacing the formerly
undifferentiated illumination of the
building’s facades. This was coupled with
the decision to make more use of the
interior lighting in the church, which the
removal of the glaring façade illumination
revealed more acutely. In addition, a
switch-off time was established for the
lighting, allowing a period of rest for both
the environment and the architecture, and
the impressive, silhouetted form of the
darkened church to stand out against the
night sky, adding a different dimension to
its visual impact.
7KHƅUVWSKDVHRIWKHSURMHFWKDV
already reduced the annual carbon
dioxide emissions by two tonnes. From
successfully applying for grant streams to
organising dark-sky festivals and carrying
out lighting tests on site, the community
of Newport has a tremendous capacity
and willpower to initiate change. Not only
has the project improved the night-time
experience of the town, but the aim is to
secure further dimming measures across
Newport that could save a total of 10
tonnes of carbon dioxide per year.
X

After

7KHƅUVWSKDVHSXW6W
Patrick’s Church in a whole
QHZ HQHUJ\HIƅFLHQW OLJKW

March 2024 BBC Sky at Night Magazine 39

Plas y Brenin outdoor
activity centre overlooks
Yr Wyddfa (Mount
Snowdon) in North Wales

Plas y Brenin, Snowdonia, Wales

DANI ROBERTSON, DYLAN PARRY EVANS & DANI ROBERTSON, DYLAN
PARRY EVANS & KEREM ASFUROGLU, DYLAN PARRY EVANS

Located in the lush heart of Snowdonia,
North Wales, Plas y Brenin is a vibrant
outdoor centre that attracts thousands of
international visitors every year. The site
KDGEHHQVXIIHULQJIURPDVLJQLƅFDQWOHYHO
of light pollution visible for miles around,
causing several issues for itself and for
biodiversity in the area surrounding it.
Together with Snowdonia National Park
Authority and Prosiect Nos, the North
Wales Dark Sky Partnership, a lighting
design was developed to restore the
area’s dark skies and tackle the growing

Before

concern for the region, which has been
an accredited Dark Sky Reserve since
2015. The project was conceived with an
environmentally and socially sustainable
ethos, which aims to reduce energy
waste and the impact on biodiversity,
while exploring further opportunities
to enhance the outdoor experience for
visitors after dark.
Budgets for dark-skies projects can
be low in comparison to commercial
developments, encouraging designers
to push the boundaries of creativity.

Initially envisaged as a car park lighting
improvement project, the project
expanded into a more holistic scheme
that covered the whole site. This was in
part because the existing lighting mostly
FRQVLVWHGRIƆXRUHVFHQWEXONKHDGVDQG
/('ƆRRGOLJKWVJODUHDQGXQFRQWUROOHG
light dispersal shaped the visual
experience across the space and reduced
the site’s legibility. Moreover, the lighting
was unevenly distributed, with certain
areas over-lit and other regions of the site
deprived of light. The holistic approach

After

The majority of the new
lighting was installed
below eye level

40 BBC Sky at Night Magazine March 2024

Before

After

Fluorescent bulkheads
were replaced with warm,
downward-facing lights

sought to strike a balance between lit and
unlit spaces and create a visually pleasant
and consistent experience.

Low-level lighting
After investigating the relative costs of
the large range of luminaires offered by
international suppliers, budget decisions
were made that sought the best value for
money. Warm-coloured, glare-free, lowintensity lighting was installed to meet
dark-sky-friendly measures and create
a more inviting atmosphere, while high
HQHUJ\HIƅFLHQF\HQVXUHGWKDWORQJHU
term costs would not be exceeded. The
majority of the newly installed lighting at
Plas y Brenin is situated below eye level
and at door height; by focusing on the
diffusion of light across a horizontal plane,
illumination is at a more human scale.
There were also areas where vertical
illumination was essential to make
ZD\ƅQGLQJHDVLHU7KLVZDVGRQHZLWK
the imperative that luminaires faced
downwards, avoiding upwards travelling
light. To create a textured visual character
unique to the site, luminaires with elliptical
and forward throw effects were used to
increase reach and coverage.
$OOƆRRGOLJKWVZHUHUHPRYHGIURPWKH
VLWH5HVSRQVLYHLOOXPLQDWLRQZDVƅWWHGDW
all less well-used entrances, with passive
infrared sensors (PIRs) introduced to
avoid unnecessary illumination, where
lights only come on when movement
is detected. PIR technology was also

The new design created
DXQLƅHGDQGLQYLWLQJIHHO
across the whole site

put into areas where supplying mains
power proved to be challenging, with
solar lanterns deployed as a low-energy
solution. To minimise material and
economic waste, the existing bollard
bodywork was refurbished so that only
light sources were replaced.
Gratifyingly, the project has encouraged
the return of bats to the site to forage
around hedgerows that were formerly
too brightly illuminated. The project has
ensured that a core area of the dark-sky
reserve is further enhanced and protected,
offering an inviting night-time experience
aligned with Plas y Brenin’s brand and
environmental ethos.
The overall transition to LEDs has
maximised the longevity and energy
savings of the scheme, and the highly

HIƅFLHQWOLJKWLQJSURGXFWVLQVWDOOHGKDYH
cut annual carbon dioxide emissions by
two tonnes.
The multiple award-winning project
has also served as an exemplar for other
environmentally and dark-sky-orientated
lighting schemes. It was featured on BBC
One’s &RXQWU\ƅOH programme in 2022,
extending awareness about the important
role of considerate lighting design within
the dark skies movement.

Kerem Asfuroglu is
the founder and
director of Dark
Source lighting
design studio

March 2024 BBC Sky at Night Magazine 41

GALLOWAY ASTRONOMY CENTRE
Promoting the Dark Skies of Galloway for 20 years
3VJH[LKULHY[OL<2»ZÄYZ[+HYR:R`7HYRL_WLYPLUJLMVY`V\YZLSMV\Y
spectacular night sky full of stars.
-VYOLSWI\`PUNVY\ZPUNH[LSLZJVWL[HSR[V\ZÄYZ[
At the Centre we provide:
 Tours of the night sky using our 400mm telescope
 Astronomy courses
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To book contact Mike Alexander

              

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The

Possibilities
are
Endless

Recycle your magazine and seven days
later it could come back as your newspaper

www.recyclenow.com

16-PAGE
CENTRE
PULLOUT

MARCH 2024

COATHANGER
CROSSING

PETE LAWRENCE

Catch morning comet
C/2021 S3 PanSTARRS’s
close encounter with the
Coathanger Cluster

VOLCANOES ON
THE MOON

Hunt down lunar domes from
our Moon’s volcanic past
About the writers
Astronomy
expert Pete
Lawrence is a
skilled astro
imager and a
presenter on The Sky at
Night monthly on BBC Four

Steve
Tonkin is
a binocular
observer.
Find his tour
of the best sights for
both eyes on page 54

Also on view
this month…
✦ Brightening comet
12P/Pons–Brooks
✦ Waxing crescent Moon,
Jupiter and the Pleiades
✦ Mercury at greatest
eastern elongation

SUPER
BOWL
Six beautiful galaxies to
find in the Bowl of Virgo
Red light friendly

To preserve your night
vision, this Sky Guide
can be read using a red
light under dark skies

Get the Sky
Guide weekly
For weekly updates on
what to look out for in
the night sky and more,
sign up to our newsletter
at www.skyat
nightmagazine.com

March 2024 BBC Sky at Night Magazine 43

MARCH HIGHLIGHTS
Friday X

1

Bright Venus
appears very
close to Mars this morning,
but the mag. +1.3 Red
Planet is rapidly lost to the
brightening dawn sky.

Your guide to the
night sky this month

The view through
7x50 binoculars

Saturday

2

Minor planet
3 Juno
reaches opposition
today, when it can be
found shining at mag. +8.6
against the stars of Leo.

Sunday

10

The Moon reaches
perigee at 07:07 UT,
a couple of hours prior
to new Moon at 09:03
UT. According to the ‘official’
definition, this counts as a new
supermoon, although you won’t
be able to see it.

Thursday

14

16

Look
directly
above this evening’s
46%-lit waxing
crescent Moon and
see whether you can spot
mag. +1.6 Elnath (Beta (β)
Tauri) immediately north
of it around 21:20 UT.

Monday

Wednesday

Friday

Saturday

The
clair-obscur
effect known as the
Eyes of Clavius is
visible around 19:50 UT.

The Northern’s
Hemisphere’s vernal
equinox occurs
today, the centre of
the Sun’s disc moving south to
north across the celestial
equator at 03:06 UT.

Venus
is 27
arcminutes from
Saturn at 06:00 UT
as they rise above the
east-southeastern horizon.
Mag. –3.8 Venus should be
visible, but at mag. +0.8 and
against the bright dawn
twilight, Saturn will be tricky.

See
this
evening’s 98%-lit
waxing gibbous
Moon occult mag. +4.0
Sigma (σ) Leonis at
around 21:00 UT.

Monday

Tuesday

18

25

PETE LAWRENCE X 7

Saturday X

Catch this
evening’s
26%-lit waxing
crescent Moon
around 23:40 UT and look out
for the Pleiades open cluster
located 3.2 ° to the northeast.

This
morning’s

full Moon
experiences a
penumbral lunar eclipse. This
is not well presented for UK
observers, who only get the
start of an already difficult-tosee event, just before the Moon
sets below the horizon.

20
26

As the just
past full
Moon rises this
evening, around
20:30 UT, look out for mag. +1.0
Spica (Alpha (α) Virginis) very
close to it.

44 BBC Sky at Night Magazine March 2024

22

23

NEED TO

KNOW
The terms and symbols
used in The Sky Guide

Sunday X

3

Universal Time (UT)
and British Summer
Time (BST)

This
morning’s
last quarter Moon sits
immediately west of
M4 and 1.9 ° west of Antares
(Alpha (α) Scorpii).

Universal Time (UT) is
the standard time used
by astronomers around
the world. British
Summer Time (BST) is
one hour ahead of UT

RA (Right ascension)
and dec. (declination)

Monday

11

This
evening’s
2%-lit waxing
crescent Moon sits
7.5° east-northeast from
mag. –1.2 Mercury, both
visible 30 minutes after
sunset, very low above
the western horizon.

These coordinates are the
night sky’s equivalent of
longitude and latitude,
describing where an object
is on the celestial ‘globe’

Wednesday X

13

See
the
16%-lit waxing
crescent
Moon 3 ° northwest
of Jupiter as both
objects approach the
west-northwestern
horizon this evening
around 22:30 UT.

Family friendly
Objects marked
with this icon are perfect
for showing to children

Naked eye
Allow 20 minutes
for your eyes to become
dark-adapted

Sunday X

17

Four
popular
clair-obscur effects
are visible today:
the Lunar X and V, optimal at
14:21 UT in daylight; the Face
in Albategnius, best seen
around 22:15 UT; and Nessie
in the crater Ptolemaeus is
visible around midnight.

Photo opp
Use a CCD, planetary
camera or standard DSLR

Binoculars
10x50 recommended

Small/
medium scope
The Face in Albategnius

Reflector/SCT under 6 inches,
refractor under 4 inches

Sunday

24

Large scope

Mercury
reaches
greatest eastern
elongation,
appearing separated
from the Sun by 18.7° in
the evening sky. The mag.
–0.1 planet sets nearly two
hours after the Sun.

W Friday

29

The
eighthmagnitude comet
C/2021 S3
PanSTARRS crosses the
Coathanger Cluster
(Collinder 399) from today
through to 31 March.

Reflector/SCT over 6
inches, refractor over 4 inches

Family stargazing

GETTING STARTED

The term ‘conjunction’ has a specific technical meaning,
but it’s also used loosely to refer to when one celestial
object appears close to another. There are several
conjunctions that young observers can look out for in March. On
13 March, the crescent Moon sits near bright Jupiter in the
evening. The following evening, it will have moved to sit near the
Pleiades. Suggest sketching where the Moon is in relation to the
cluster stars. If it’s hard to see the cluster with the naked eye, use
binoculars; both objects should fit into the same field of view.
www.bbc.co.uk/cbeebies/shows/stargazing

IN ASTRONOMY
If you’re new to
astronomy, you’ll find
two essential reads on our
website. Visit bit.ly/10_
easylessons for our
10-step guide to getting
started and bit.ly/buy_
scope for advice on
choosing a scope

March 2024 BBC Sky at Night Magazine 45

THE BIG THREE
DON’T MISS

The top sights to observe or image this month
102

CYGNUS
`

g

109

_
Rasalhague

HERCULES

Albireo
110

VULPECULA

Comet
C/2021 S3
PanSTARRS
and the
Coathanger

OPHIUCHUS

_

10

31 Mar
13
4
9

M27
a

111

1

c b

_

Collinder 399
(Coathangar Cluster)
¡
C/2021 S3
NGC 6572
c
11 PanSTARRS
21 Mar
NGC 6633

`

62

e
Tarazed
Altair

46 BBC Sky at Night Magazine March 2024

ALL PICTURES: PETE LAWRENCE

67

73

Collinder 350

70
68

Poniatowski’s
Bull

11 Mar

c
59

Alya

61

4

d

60

+

SERPENS
CAUDA

b

1 Mar
o
k
i

Alshain

20 Feb

`

AQUILA

Althalimain h

12

d M11

j

Gum 84-85

_
¡

M16
NGC 6605

b

SCUTUM

BEST TIME TO SEE: 1–17 March and
29–31 March
Visible in the morning sky, comet
C/2021 S3 PanSTARRS is predicted
to shine at a binocular-friendly eighth
magnitude all month. It’s currently
passing through a part of sky more
associated with summer than spring,
heading north-northeast from Serpens
&DXGDWKURXJK$TXLOD6DJLWWDDQGƅQDOO\
into Vulpecula. Its incursion into Vulpecula
takes it across the deep-sky object known
as Collinder 399, Brocchi’s Cluster or the
Coathanger Cluster. Despite its name, the
Coathanger is an asterism rather than a
true star cluster.
This region of sky does get to a decent
altitude before dawn kicks in, so you
VKRXOGƅQGWKHUHDUHSOHQW\RI
opportunities to look for and follow the
comet. On 1 March, you’ve got until
around 05:00 UT before astronomical
twilight begins and true darkness ends. By
the end of March, this occurs earlier at
around 04:50 BST (03:50 UT).
On 1 March, the comet will be located in
a region of sky that, at the start of dawn,
has an altitude around 22° as seen from
the centre of the UK. By the end of the
month, when the comet is passing
through the Coathanger Cluster, its
altitude will have virtually doubled to
around 40° while under true darkness.
Unusually for a comet, this one will be
fairly well positioned and shouldn’t cause
\RXWRRPXFKVWUHVVWRƅQG
7KHUHLVRQHƆ\LQWKHRLQWPHQWWKRXJK
the Moon. This will interfere with views of

m
`

Cebalrai
a
66

IC 4756

18

SAGITTA

NGC 465

72

a

M23

M17

S C/2021 S3 PanSTARRS tracks from Serpens to the Coathanger in Vulpecula this month

the comet from 18 March through to the
end of the month. However, at the early
part of that range, the Moon will be on the
other side of the sky and not too much of
a nuisance. At the end of that date range,
trying to grab the comet as soon as it’s
above the horizon is the best strategy as
you may be able to locate it before the
Moon has time to rise too high.
There are several key nights that will
KHOS\RXƅQGWKHFRPHWLI\RXŝUHKDYLQJ
trouble locating it. On the night of 3/4

March, it lies very close to mag. +3.2 Eta
(d) Serpentis, moving into the vicinity of
mag. +5.2 star 59 Serpentis in the early
hours of 7 March. On the mornings of 14
and 15 March, it sits 3.3° northwest of
mag. +4.6 Theta (e) Serpentis. As we’ve
mentioned, the Moon interferes in the last
half of March, a key date here being the
morning of 22 March, when the comet sits
really close to mag. +3.0 Zeta (ζ) Aquilae.
The Coathanger crossing takes place
between 29 and 31 March.

S The comet crosses Collinder 399 from 29 March, reaching the coathanger-like asterism
on the 30th. Your best chance to see it is at around 03:00 UT, before the Moon gets too high

Almach a

TRIANGULUM
NGC 925

q

a

NGC 752

`

NGC 278

NGC 185
NGC 147

Comet 12P/
Pons–Brooks

ARIES
Hamal

31 Mar

Collinder 21

_

M31

i
Mothallah

+
Mirach

NGC 672

M33

`

26 Mar

M32

M110

NGC 404

21 Mar

BEST TIME TO SEE: 1–17 March and
26–31 March
Comet C/2021 S3 PanSTARRS is not
the only bright comet around at the
moment. 12P/Pons–Brooks is predicted to
brighten from mag. +7.1 to +5.2 throughout
the month, the latter value taking it close
to naked-eye territory. There’s a bit of
cosmic balance at play too, because
whereas C/2021 S3 is best in the early
morning sky, 12P is best in the evening sky.
12P starts its monthly track just north of
the Great Square of Pegasus, technically
within Andromeda. As the sky gets
properly dark from the centre of the UK,
it’ll be approximately 24° above the
west-northwestern horizon.
The comet then heads southeast,
brightening as it goes. On 12 March, it’ll be
just shy of 2° north of mag. +3.2 Delta (δ)
Andromedae, zipping past this star over
the following evenings before exiting
Andromeda and entering Pisces just
before midnight on 14 March.

_

`

o

Sheratan

NGC 772

a Mesarthim

l
16 Mar

12P/Pons–Brooks
b

q

/

e

m

11 Mar
6 Mar

¡

1 Mar

M74

d
c

d
k

Alpheratz

_

PGC 3529

PISCES

PEGASUS

PGC 1467

S Where to see 12P/Pons–Brooks on early evenings in March, brightening to possible
naked-eye visibility as it travels from Andromeda towards Hamal (Alpha Arietis)

,WZLOOWKHQSDVVWKURXJKWKHLOOGHƅQHG
QRUWKHUQƅVKRI3LVFHVWUDFNLQJVRXWKHDVW
to eventually arrive at a position very
close to mag. +2.0 Hamal (Alpha (α)
Arietis). On the evening of 31 March,
comet 12P/Pons–Brooks lies less than half
a degree from this star. The expanding
evening twilight will cause issues at the
end of the month, Hamal being just 10°
above the west-northwestern horizon as
true darkness falls. The Moon moves

through the region mid-month, but as a
thin waxing crescent it shouldn’t become
an issue until 18 March, moving out of the
way again around 26 March.
The comet will be in a part of the sky
with bright Jupiter and less bright Uranus
nearby, especially towards the end of the
month. With the Andromeda Galaxy, M31,
on the table too, there is plenty of
opportunity here for a stunning
astrophoto to be taken of the scene.

Crescent Moon, Jupiter and the Pleiades
BEST TIME TO SEE: Evenings of 13 and 14 March
There’s a lovely encounter between the waxing crescent
Moon and Jupiter on the evening of 13 March. This bright
meeting will be a great target if you have a smartphone with a
camera sensitive enough to record astronomical objects. The
Moon will have an illuminated phase of 16% and will appear 3.8°
from Jupiter as true darkness arrives. The gap continues to close
until just before they set at around 23:00 UT, when they will be
just 2.8° apart.
The next evening, the Moon will have moved further east to sit
between the dim planet Uranus and the Pleiades open cluster,
M45. The Moon’s phase will have increased to 26% on this date,
slim enough to allow the stars of the Pleiades to be easily seen
above and left of the Moon’s position as seen from the UK.
Again, if you had success taking a photo of the Moon and
Jupiter together using a smartphone, have a go to see whether
you can record the Moon and the Pleiades together. With a wide
enough view, you should also be able to capture mag. +0.8
Aldebaran (Alpha (α) Tauri) together with the V-shaped Hyades
open cluster. As a challenge, see whether you can record Uranus
as well.

S The waxing crescent Moon creates a stunning scene with
Jupiter, the Pleiades and Hyades open clusters in mid March

March 2024 BBC Sky at Night Magazine 47

THE PLANETS

Our celestial neighbourhood in March

PICK OF THE

MONTH
Mercury

PETE LAWRENCE X 2

Best time to see: 25 March,
40 minutes after sunset
Altitude: 10°
Location: Pisces
Direction: West
Features: Phase, surface markings
Recommended equipment:
150mm scope or larger
Mercury is an evening planet, but having
passed superior conjunction on 28
February, it’s pretty close to the Sun at
the start of March and won’t be seen. The
good news is that the inclination of the
ecliptic plane – the projection of Earth’s
orbital plane in the sky – is steep against
the western horizon at this time of year at
sunset. The Sun, Moon and main planets
stay on or near the ecliptic, and the steep
angle helps keep Mercury above the
horizon at a better altitude than if the
inclination were shallow.
On 7 March, Mercury shines at mag. –1.4
and sets 40 minutes after the Sun. If you
KDYHDƆDWZHVWHUQKRUL]RQ\RXPLJKWEH
able to pick it up using binoculars, say 20
minutes after sunset, but it won’t be easy.
The bright evening twilight sky will do a
very good job of hiding the planet! On

S In later March, Mercury is reasonably well placed above the western horizon after sunset

the evening of 8 March, Mercury sits half
planet as seen from the UK.
a degree from Neptune. Unfortunately,
By the middle of the month, Mercury
though, at mag. +7.9 you’re not
sets an impressive 90 minutes
going to see this dim planet.
after the Sun and, still shining
Jump forward to 11
brighter than mag. –1.0
March, when mag. –1.2
on 14 March, should be
Mercury sets an hour
relatively easy to see,
after sunset. Wait for
given clear weather.
30 minutes after the
Its position improves
Sun has gone down
through to 25 March
and the planet should
when it sets two hours
become visible. A slender
after the Sun. By then
2%-lit waxing crescent
its brightness will have
Moon sits 7.5° east-northeast
decreased to around mag.
of Mercury on this date,
S Mercury is an evening +0.1, but it should still be fairly
above and to the left of the
easy to see.
planet this month

phase and relative sizes of the planets this month. Each planet is
The planets in March The
shown with south at the top, to show its orientation through a telescope

Venus
15 Mar

Mars
15 Mar

Jupiter
15 Mar

Saturn
15 Mar

Uranus
15 Mar

Neptune
15 Mar

Mercury
1 Mar

Mercury
15 Mar

Mercury
31 Mar
0

48 BBC Sky at Night Magazine March 2024

10

20
30
40
ARCSECONDS

50

60

Venus
Best time to see: 1 March,
20 minutes before sunrise
Altitude: 2° (very low)
Location: Capricornus
Direction: East-southeast
Venus is visible in the morning
sky, but is getting trickier with
each passing day. On 1 March,
it shines at mag. –3.8 and rises
just 40 minutes before the Sun.
On this date it sits close to
mag. +1.3 Mars, but this planet
is rapidly lost in the bright
morning sky. Venus sits less
than half a degree from mag.
+0.8 Saturn on 22 March, but
the pairing will be lost in the
dawn twilight. By the time
the end of March arrives,
Venus will rise just 16 minutes
before the Sun.

Mars
Mars is in the morning sky,
but is unlikely to be seen.

Jupiter
Best time to see: 1 March,
18:30 UT
Altitude: 42°
Location: Aries
Direction: Southwest
Jupiter is slowly losing its
battle against the evening
twilight. On 1 March, it appears
40° up against a fairly dark sky,
but by the end of the month
it’s only 16° up under similar
darkness. Despite this, Jupiter
remains bright and beautiful to
look at through a telescope.
On 1 March, it shines at mag.
–2.0, dimming slightly to mag.
–1.9 by the end of the month.
A 16%-illuminated waxing
crescent Moon will appear 3.8°
from Jupiter as true darkness
arrives on 13 March. The
distance closes until the Moon
sits 3° northwest of Jupiter as
both objects approach the
west-northwestern horizon
around 22:30 UT.

Saturn
After lining up with the Sun in

solar conjunction at the end
of last month, Saturn is now
a morning object, but it is still
too close to the Sun to be seen
properly. On 22 March, it sits
26 arcminutes from mag. –3.8
Venus, but at mag. +0.8 and
battling against the bright
dawn twilight, Saturn is
unlikely to be seen.

Uranus
Best time to see: 1 March,
19:40 UT
Altitude: 40°
Location: Aries
Direction: West-southwest
The observing window closes
for Uranus this month, the
evening twilight rapidly
expanding to engulf the
mag. +5.8 planet. It’s visible
under dark-sky conditions
at the start of March, 40°
above the west-southwestern
horizon on 1 March. The
apparent separation between
Uranus and mag. –2.0 Jupiter
is closing currently. On 13
March, both planets appear
6.3° apart. A beautiful 16%-lit
waxing crescent Moon lies
3.8° west-northwest of Jupiter
on this date around 20:00 UT.
By the end of the month,
Uranus will be just 14° above
the western horizon as true
darkness falls. Jupiter will be
3.5° to the west of the planet
at this time.

JUPITER’S MOONS: MARCH
Using a small scope you can spot Jupiter’s biggest moons. Their
positions change dramatically over the month, as shown on the
diagram. The line by each date represents 00:00 UT.
DATE

WEST

EAST

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23

Neptune

24

As it reaches solar conjunction
on 17 March, Neptune isn’t
currently visible.

25
26
27

FREE BONUS
CONTENT

28
29
30
31
1
8

Print planet observing forms
www.skyatnightmagazine
.com/bonus-content

7

6

5

4

3

2

1

0

2

1

3

4

5

6

7

8

arcminutes
Jupiter

Io

Europa

Ganymede

Callisto

March 2024 BBC Sky at Night Magazine 49

THE NIGHT SKY – MARCH

Su

Explore the celestial sphere with our Northern Hemisphere all-sky chart

m

m

er

ia
Tr

ng

le

Vega

`
R

3. The centre of
the chart is the
point directly
over your head.

18:07 UT

21 Mar 2024

06:09 UT

18:26 UT

31 Mar 2024

06:44 BST

19:44 BST

a

TE
BOÖ

M3

17:48 UT

06:33 UT

e

06:56 UT

11 Mar 2024

Kit

1 Mar 2024

`

_

Sunset

_

STAR-HOPPING
PATH

Sunrise

b

CO
BO RON
RE
AL A
IS

SERP
EN
S
CAPUT
b

Date

E A ST

Sunrise/sunset in March*
ASTEROID
TRACK

a

a

COMET TRACK

_

Arcturus

Moonrise in March*
Moonrise times
17 Mar 2024, 09:20 UT

5 Mar 2024, 04:45 UT

21 Mar 2024, 14:05 UT

_

9 Mar 2024, 06:44 UT

25 Mar 2024, 18:58 UT

13 Mar 2024, 07:29 UT

29 Mar 2024, --:-- UT

¡

QUASAR

Vindemiatrix

*Times correct for the centre of the UK

STAR BRIGHTNESS:
MAG. 0
& BRIGHTER

VIR

GO

Lunar phases in March
Monday

Tuesday

Wednesday

Friday
1

Saturday
2

D
To eep
ur -S
, p ky
ag
e5

Sunday
3

MAG. +2
4

5

6

7

8

9

N

E
CHART: PETE LAWRENCE

11

12

13

14

15

16

17

18

19

20

21

22

23

24

25

26

27

28

29

30

31

W COMPASS AND
FIELD OF VIEW
S

6

a

Ecliptic

_

Sp

ica

ST

5º

NEW MOON

27th

A
HE

MAG. +4
& FAINTER

10

UT
SO

MAG. +3

G

b

Thursday

MAG. +1

Bowl

PLANET

1 Mar 2024, --:-- UT

3

ASTERISM

M5

Ci

rcl

et

METEOR
RADIANT

_

2. The lower half
of the chart
shows the sky
ahead of you.

b

THE MOON,
SHOWING PHASE

`

VARIABLE STAR

M13

DOUBLE STAR

K
e
ys
to
ne

DIFFUSE
NEBULOSITY

1. Hold the chart
so the direction
you’re facing is
at the bottom.

LES

PLANETARY
NEBULA

How to use this chart

HERCU

GLOBULAR
CLUSTER

On other dates, stars will be in slightly different positions
because of Earth’s orbital motion. Stars that cross the
sky will set in the west four minutes earlier each night.

M92

OPEN CLUSTER

a

GALAXY

LY
RA

CONSTELLATION
NAME

1 March at 00:00 UT
15 March at 23:00 UT
31 March at 23:00 BST

ST

PERSEUS

STAR NAME

TH
EA

Arcturus

When to use this chart

NO
R

KEY TO
STAR CHARTS

a

MILKY WAY

FULL MOON

50 BBC Sky at Night Magazine March 2024

COR

NORTH
M1
10

FREE BONUS
CONTENT

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Southern Hemisphere guide

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Paul and Pete’s
night-sky highlights

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March 2024 BBC Sky at Night Magazine 51

SOUTH

MOONWATCH

March’s top lunar feature to observe
N

ƆRRU,WVPDLQLQWHUQDOIHDWXUHLVWKHNPEHDXWLIXOO\
bowl-shaped crater Isidorus A, offset from the centre
Type: Crater
of Isidorus towards the west. In contrast, Capella’s rim
Size: 50km
is so worn that it can be tricky to make out under
Longitude/latitude: 34.9 ° E, 7.6° S
FHUWDLQOLJKWLQJFRQGLWLRQV:LGHLOOGHƅQHGWHUUDFHV
Age: 3.9 billion years
create an undulating surface that extends from the
Best time to see: )LYHGD\VDIWHUQHZ
rim edge toward the singular central mountain at the
Moon (14–15 March) or four days after full
heart of the crater. Even this isn’t particularly jagged,
Moon (28–29 March)
rising in a gently rounded fashion to a sharp central
Minimum equipment: 50mm refractor
point. Capella has an estimated depth (from the rim
HGJHWRWKHORZHVWSRLQWRQWKHFUDWHUŝVƆRRU RI
1RWDOOFUDWHUVDUHVKDUSO\GHƅQHG7KHUH
around 3.5km.
are plenty of ancient, battered examples,
The most striking feature associated
50km Capella being one. It lies just north
with Capella is best seen at low
of 350km Mare Nectaris (Sea of Nectar)
illumination when the terminator is close
and forms a close pair with 41km Isidorus
by. At such times it’s possible to see a
valley passing northwest–southeast
to the west. When we say close, we mean
across Capella. This is another ancient
very close, both craters apparently sharing
feature, older than Capella: Vallis Capella.
ZKDWORRNVDWƅUVWJODQFHDFRPPRQ
It’s 110km long but pointed, spanning 14km
section of rim. However, Capella is the one
at the widest end to the northwest and narrowing to
that overlaps Isidorus, the former being slightly the
younger of the pair.
about 2km at the southeast end before the valley
Not that you’d guess this from their appearance,
peters out.
Capella looking very battered and distinctly rounded.
Various smaller craters litter the area which have
,VLGRUXVKDVDEODQGULPVXUURXQGLQJDƆDWLQWHUQDO
been divided up into satellites of Isidorus to the west
and Capella to the east. The largest
crater located east of Capella is the
MARE TRANQUILLITATIS
ODYDƅOOHGIRUPRINPGutenberg.
This is an interesting crater to observe
DQGLVDVVRFLDWHGZLWKDVHULHVRIƅQH
Rimae Gutenberg
rilles extending from Gutenberg up to
the northwest. Running for a distance of
Vallis
330km, the rilles are collectively known
Capella
as Rimae Gutenberg. Being just 2km
Capella
wide, a 300mm or larger scope is
Isidorus
SINUS
recommended to observe them.
Isidorus
A
ASPERITATIS
To the south of Isidorus, within the
Gutenberg
lava plains of Mare Nectaris, lies the
ancient 131km ghost crater Daguerre.
This is best seen when the lighting is
oblique, when the terminator is close by.
It has been almost completely
Madler
Daguerre
swallowed by the lava of Mare Nectaris,
but its form echoes superbly on the
Theophilus
mare’s lava surface, its ancient outline
preserved beautifully.
7RWKHZHVWRI,VLGRUXVOLHVDƆDW
MARE NECTARIS
region of lava that joins Mare Nectaris
Cyrillus
to Mare Tranquillitatis further to the
north. This is not smooth lava and is a
region that shows a rough texture when
the illumination is low in its sky. It is
named Sinus Asperitatis, the Bay of
Roughness. To the south of this bay
Dilapidated Capella is slashed
Catharina
lies a spectacular trio of craters:
by the deep rift of Vallis Capella
and sits in a region scarred by
101km Theophilus, 98km Cyrillus
many small impact craters
and 101km Catharina.

Capella

Capella’s rim is
so worn that it
can be tricky to
make out

52 BBC Sky at Night Magazine March 2024

COMETS AND ASTEROIDS
A potential binocular catch, 11th-largest
asteroid 3 Juno is at its brightest in March

Asteroid 3 Juno reaches opposition on 3 March, when it can be
found in southern Leo, near the border with Sextans, shining at
mag. +8.6. It starts the month close to mag. +4.8 58 Leonis and
shining at mag. +8.8 – a binocular possibility, but best seen using
DVPDOOWHOHVFRSHDWORZPDJQLƅFDWLRQ,WKHDGVQRUWKZHVW
clipping the border between Leo and Sextans. On 16 March, the
asteroid crosses into Leo, very close to mag. +6.4 37 Sextantis. Its
magnitude will have dimmed to +9.1 and it will continue to dim as
it tracks northwest. By the end of March, it will be located less
than a degree east-southeast of mag. +5.7 49 Leonis, having
faded to mag. +9.5.
3 Juno is the 11th-largest asteroid, with a mean diameter of
247km. It’s the second-largest stony (S-type or siliceous) asteroid
(after 15 Eunomia) and contains 1 per cent of the entire mass of
the asteroid belt, and around 3 per cent that of the largest body
in this orbital region, the dwarf planet Ceres. Juno’s elliptical orbit
is highly eccentric, and takes it out as far as 3.35 AU from the
Sun and in as close as 1.99 AU. The entire orbit takes 3.36 years
and is quite inclined, with a tilt of 12° to the ecliptic plane.
It’s a highly studied object; observations suggesting it has a
massive 100km impact crater on its surface. Spectral analysis
suggests it may be the source of chondritic or stony meteorites
that have impacted Earth.

NGC 3377

NGC 3489

M105
NGC 3384
M96
M95

NGC 3628
M65

M66

Leo I
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31 Mar
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3 Juno

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21 Mar

56

NGC 3169
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59

11 Mar

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1 Mar
58

36

SEXTANS

NGC 3640
55

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26

33

S See Juno skirt the border between Sextans and Leo this month

Its location in southern Leo this month, combined with a
small-telescope-favourable magnitude, makes this an ideal time
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LVWRLPDJHRUVNHWFKWKHVXVSHFWHGƅHOGRYHUVHYHUDOQLJKWV
comparing results to look for some object that is moving
between observations.

STAR OF THE MONTH
55 Cancri, a star waiting for our message

Castor

Cancer the Crab is represented
by a faint, inverted Y shape.
The base of the Y, which marks
the north point of the pattern,
is mag. +4.0 Iota (ι) Cancri.
Located 1.3° further to the
east-southeast is mag. +5.9
Rho1 (l1) Cancri, with mag. +5.2
Rho2 (l2) Cancri 0.8° further to
the east-southeast.
Rho1 or, as we’ll call it from
now on, 55 Cancri, is an
interesting star that can ignite
the imagination. Before we get
on to that, there’s an easy way
WRFRQƅUP\RXKDYHWKHULJKW
star: mag. +6.3 53 Cancri lies
4.5 arcminutes south and
slightly west of 55 Cancri,
forming a distinctive and
easily recognised pair.

55 Cancri is located 41
lightyears from the Sun. It’s a
K0 IV–V type star; a cool, main
sequence or sub-giant star. It’s
not alone, having a dim mag.
+13.2 red dwarf to keep it
company. From Earth, the pair
appear separated by 85
arcseconds and seem to be
gravitationally bound to one
another. The primary, 55
Cancri A, is marginally smaller
and less massive than our Sun,
and is around 60 per cent as
luminous.
&DQFUL$DOVRRIƅFLDOO\
named Copernicus, is known
WRKDYHDIDPLO\RIƅYH
planets, possibly even more.
On 6 July 2003, a message
named ‘Cosmic Call 2’ was

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55 Cancri’s Sun-like primary has at
OHDVWƅYHSODQHWVLQRUELWDURXQGLW

sent to the system. This
message will arrive in May
2044. Four of the planets orbit
Copernicus closer than Earth

orbits the Sun. 55 Cancri d, the
ODUJHVWRIWKHƅYHZLWKDPDVV
of 3.12 Jupiters, orbits at a
distance of 6 AU.

March 2024 BBC Sky at Night Magazine 53

BINOCULAR TOUR

With Steve Tonkin

Use averted vision to make these widefield gems around Coma Berenices pop
M51

M94

M63

4

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Chara

j
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Algieba

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CANES
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a

6

Melotte 111

86

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24

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¡

1. Melotte 111
10x We’ll start with a favourite ‘made for
50 binoculars’ target. Look midway
between mag. +2.9 Cor Caroli (Alpha (_)
Canum Venaticorum) and mag. +2.1
Denebola (Beta (`) Leonis) and you should
see a misty patch about 6° across. Your
10x50s will resolve it into 30 or more stars,
all of which are mag. +10.5 or brighter; any
fainter ones have been gravitationally
ejected from the cluster by a process
called mass segregation.  SEEN IT

3. M3

2. M53
10x A degree northeast of mag. +4.9
50 Diadem (Alpha (_) Comae
Berenices), there’s a small misty patch
that appears to grow in size and
brightness if you centre it in the field of
view but look at Diadem. This is the
globular cluster M53, and the trick you
used to make it grow is averted vision,
which puts the light from the object onto
a more sensitive part of your retina. We’ll
use it later for galaxy hunting.  SEEN IT

4. M94
15x Return to Cor Caroli and imagine a
70 line between it and mag. +4.2 Chara
(Beta (`) Canum Venaticorum). From
half-way along this line, navigate 1.6° to
the northeast. Here, possibly needing
averted vision at first, you should find the
13.6-million-year-old glow of light from the
spiral galaxy M94. Like all galaxies, it
benefits greatly from dark, transparent
skies, but it is usually quite easy to see
even in suburban skies.  SEEN IT

54 BBC Sky at Night Magazine March 2024

`

m
k

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Vindemiatrix

Leo Triplet
(M65, M66 &
NGC 3628)

27

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p

PETE LAWRENCE X 2

36

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23

COMA
BERENICES

b

10x Our next target is one of the finest
50 globular clusters in the northern sky,

but there are no nearby bright stars to
help you find it. However, if you look
half-way between mag. –0.1 Arcturus
(Alpha (_) Boötis) and Cor Caroli, you
should find what looks like an out-of-focus
star. Use averted vision and you will see
more of the glow of the nearly half-million
stars that comprise M3, discovered by
Charles Messier in 1764.  SEEN IT

`

Zavijava

5. M49
15x Locate mag. +4.9 Rho (l) Virginis and
70 place it on the northeast of your field
of view. On the opposite side you’ll see
two sixth-magnitude stars, just over a
degree apart and orientated southeast–
northwest. The 37-million-year-old fossil
light from M49 is the small, oval patch
between them. Using averted vision, see
how many more galaxies you can find
between M49 and Melotte 111.  SEEN IT
6. 86 Leonis star field
10x Let’s finish with a colourful star field.
50 Locate the orange-yellow mag +5.6
86 Leonis between Denebola and mag.
+2.6 Zosma (Delta (b) Leonis); compare it to
brilliant-white mag. +6.3 90 Leonis, 2° back
towards Denebola. Find the curved string
of multicoloured seventh and eighthmagnitude stars that extends 3° eastward
from 86 Leo. Scan northeast of here too, if
you like colourful stars.  SEEN IT

 Tick the box when you’ve seen each one


THE SKY GUIDE CHALLENGE

Lunar domes are remnants of the Moon’s volcanic past. How many can you find?

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b

Recommended domes
a – Arago _/`
b – Cauchy o/t
c – Gardner Megadome
d – Gruithuisen a b
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f – Kies /
JŚ0DULXV+LOOV
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i – Mons Rumker
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f

-XVWDIHZORFDWLRQVWRJHW
you started in your hunt for
OXQDUYROFDQRHV

As the Moon is well placed in the evening
sky during March, this month we’re taking
a look for lunar domes. Much of the
Moon’s detail you can view through a
telescope has come from meteoric
impacts on the lunar surface. Features
such as craters and basins are the result
of impacts that occurred a long time in
the past. However, there is evidence of
vulcanism on the Moon’s surface too.
Some of it is obvious when pointed out,
such as the dark patches around the inner
edge of the 118km crater Alphonsus, the
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FUDFNVLQWKHFUDWHUŝVƆRRU
A less obvious structure which can take
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dome. These are shallow, rounded
features rising to a height of perhaps
several hundred metres. Best seen when
the terminator is close by and the lighting
oblique, they can stand out surprisingly
well. When you see a lunar dome, you’re
looking at a formation resulting from a
shield volcano.

Hunting down
lunar domes can
become a bit of
an obsession
A shield volcano is a type of volcano
that produces low-viscosity lava that is
able to travel a long distance from the
eruption point and forms generally thinner
ƆRZV7KHQDPHFRPHVIURPWKHUHVXOWLQJ
shape, which looks like the domed
appearance of a warrior’s shield laid on
the ground.
There are many examples of lunar
domes, and hunting them down can
become a bit of an obsession. We have
many favourites that we can recommend
to get you started, but these are by no
means all of them.
In the east, there’s the Cauchy Tau (o)
and Omega (ω) domes, located south and
southwest of 13km crater Cauchy. The

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a huge but tricky domed structure 80km
across, with a depression at its centre. It
OLHVVRXWKRINP*DUGQHU7KH9DOHQWLQH
Dome, near the interface between Mare
Serenitatis and Mare Imbrium, is worth a
visit too. It sits 105km northwest of 3km
/LQQH,Q0DUH7UDQTXLOOLWDWLVWU\WRƅQG
Arago Alpha (α) and Beta (`).
To the west, there’s dome overload,
starting with Mons Rumker, a feature near
the northwest limb which resembles a
raspberry. Two obvious domes sit near to
0RQV5XPNHULQWKHIRUPRI*UXLWKXLVHQ
*DPPD γ) and Delta (δ). These are often
likened to upturned bathtubs! West and
north of 41km crater Marius there’s a
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Hills. Further east, towards Copernicus,
seek out Milichius Pi (π) and the superb
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In the south, around Mare Numbium
there’s Kies Pi (π), which lies immediately
west of 45km Kies. Using our guide chart,
VHHKRZPDQ\\RXFDQƅQGDQGUHFRUG

March 2024 BBC Sky at Night Magazine 55

DEEP-SKY TOUR

MICHAEL BREITE/STEFAN HEUTZ/WOLFGANG RIES/CCDGUIDE.COM, CHART BY PETE LAWRENCE

1 NGC 4517
Virgo is a sprawling constellation
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This Deep-Sky Tour has been automated
ASCOM-enabled Go-To mounts can take
you to this month’s targets at the touch of
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our free Bonus Content online.

56 BBC Sky at Night Magazine March 2024

Dip into the Bowl of Virgo to find these six
mouthwatering galaxies. Bon appétit!
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4 NGC 4632

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in our second
galactic pick,
NGC 4536

FREE
BONUS
CONTENT
Print this chart
and take the
Go-To tour.
www.skyatnight
magazine.com/
bonus-content

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NGC 4544

NGC 4527

PGC 42748
PGC 42860

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NGC 4600
NGC 4533
NGC 4536

30m
1 2h

NGC 4587

2

NGC 4636

NGC 4665

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PGC 41153

PGC 42244
NGC 4581

3

UGC 7824
UGC 7807

NGC 4643

°

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UGC 7873

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AT A GLANCE
1
F

2
S

3
S

4
M

5
T

6
W

7
T

8
F

9
S

How the Sky Guide events will appear in March

10
S

11
M

12
T

13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31
W T F S S M T W T F S S M T W T F S S

The Moon
Mercury
Venus
Mars
Jupiter
Saturn
Uranus
Neptune

SC
11 Mar: 2%-lit waxing crescent Moon near Mercury
13 Mar: 16%-lit waxing crescent Moon near Jupiter

Calendar
highlights

14 Mar: 26%-lit waxing crescent Moon near Pleiades
25 Mar: Penumbral lunar eclipse (not favourable from UK)

Moonwatch

Deep-Sky Tour

Comet C/2021 S3 PanSTARRS and the Coathanger (page 46)
The Big Three

Comet 12P/Pons–Brooks (page 47)
Crescent Moon, Jupiter and the Pleiades (page 47)

KEY

1
F

2
S

3
S

4
M

5
T

6
W

7
T

8
F

9
S

10
S

11
M

12
T

13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31
W T F S S M T W T F S S M T W T F S S

CHART BY PETE LAWRENCE

Observability

IC
Optimal

Poor

Morning
twilight

Daytime

SC Superior conjunction

Best viewed

Sky brightness
during lunar phases

Inferior conjunction
(Mercury & Venus only)

Evening
twilight

Night

OP Planet at opposition
Meteor radiant peak

Full Moon
First
quarter
Last
quarter
New Moon

'DUN ƅUVW Light (full
quarter)
Moon)

58 BBC Sky at Night Magazine March 2024

Dark (last
quarter)

Total darkness
(new Moon)

Planets in conjunction

In association with

MASTERCLASS

IMAGING THE PLANETS
Join host and editor Chris Bramley for a
three-part series of online masterclasses
all about imaging the planets, taking
them from dots of light to real worlds

rich in detail – from Saturn’s majestic
rings and the cloud bands of Jupiter
to the rocky terrain of Mars. The three
talks, from some of the best planetary

imagers in the game, will prepare you
for the fantastic period of planetary
apparitions coming in 2024, with expert
insights into capture and processing.

MATT_GIBSON/ISTOCK/GETTY IMAGES, PETE LAWRENCE X 2,
DAMIAN PEACH X 2, MARTIN LEWIS X 2

Book each Masterclass for £15 • Book all three at once and save £9
All registrants will also receive a link to view a recording of each talk after it has aired

Masterclass 1

Masterclass 2

Masterclass 3

Pete Lawrence

Damian Peach

Martin Lewis

Sky at Night co-presenter and
expert astro imager

World-renowned astrophotographer,
lecturer and writer

Prize-winning planetary photographer

The planets in their prime

Capturing Jupiter on camera

Join us to
understand why the
observing prospects
for Venus, Mars,
Jupiter and Saturn
improve markedly in the second half of
this year, and for capture and processing
advice that will prepare you for taking
great images of the spectacle.

Take a front row
seat as we look
at the special
considerations for
capturing the largest
planet in the Solar System, such as its
rapid spin, and how to process images
to reveal remarkable details in Jupiter’s
cloud bands and even its moons.

Thursday 21 March 2024, 7pm GMT

Thursday 25 April 2024, 7pm BST

10 (less-well-known) ways to
improve your planetary imaging
Discover 10 nifty tips
and tricks to improve
your planetary
imaging, based on
Martin’s wealth of
practical experience photographing the
planets with his home-built 222mm and
444mm Dobsonian telescopes.
Thursday 23 May, 7pm BST

Save 20% when you book
all three Masterclasses!
Visit skyatnightmagazine.com/virtual-events to find out more

With construction of the Square Kilometre Array now in full swing,
Govert Schilling looks ahead to the largest radio observatory ever built

ILLUSTRATION: SKAO

he largest and most sensitive
radio observatory in history, the
Square Kilometre Array is currently
being built in two remote areas
in the Southern Hemisphere: the
Great Karoo semi-desert in South
Africa and the outback of Western Australia. As

60 BBC Sky at Night Magazine March 2024

\RXUHDGWKLVLQVWDOODWLRQRIWKHƅUVWRIIRXUGLVKHV
at the site in South Africa should be under way.
Eventually, the entire SKA observatory will consist
of almost 200 radio dishes and more than 130,000
smaller antennas, distributed over two continents.
6.$LVH[SHFWHGWROHDYHLWVPDUNLQHYHU\ƅHOGRI
astronomy, from solar physics to cosmology. X

After years in development,
WKHƅUVWDQWHQQDVRIWKHZRUOGŝV
biggest radio observatory are
due to be deployed this year

March 2024 BBC Sky at Night Magazine 61

S First to be assembled at the South African site, 500km north-east of Cape Town, was one of two prototype mid-frequency dishes in

2019. Construction on both continents began in earnest in late 2022, with the first antennas due to be installed at both sites this year

NASIEF MANIE/SARAO X 2, SKAO X 2, SONJA BLOM/ALAMY STOCK PHOTO, PGIAM/ISTOC/GETTY IMAGES,
THANAPOL SINSRANG/ISTOCK/GETTY IMAGES, MARK GARLICK/SCIENCE PHOTO LIBRARY/ALAMY X 2

X

At the SKA Global Headquarters at Jodrell Bank
Observatory in Cheshire, UK, close to the venerable
76-metre Lovell Telescope, SKA director Phil Diamond
recounts the history of the project.
“More than 30 years ago, in October 1990,
University of Manchester radio astronomer Peter
Wilkinson presented the idea of a ‘hydrogen array’
at a conference in Albuquerque – an instrument
to precisely map the distribution of cold, neutral
hydrogen gas in the Universe using radio waves.
Back then, the Westerbork Synthesis Radio
Telescope in the Netherlands and the Very Large
Array in New Mexico were the most powerful radio
observatories in the world,” explains Diamond, “and
astronomers wondered what the next big step would
EH7KHVHƅUVWLGHDVHYHQWXDOO\OHGWRWKHREVHUYDWRU\
that we’re building right now.”
Even in those early stages, it became clear that
the new observatory would consist of two parts:
an interferometer of mutually connected large
dish antennas for observations at medium radio
wavelengths (SKA-Mid), and an extended network
of smaller dipole antennas to detect longer radio

waves at much lower frequencies (SKA-Low). Both
arrays require an extremely ‘silent’ environment, far
away from any form of human radio interference.
Both South Africa and Australia were hopeful of
hosting the future array. “But if only one country
were chosen, the other partner would have left
the project,” says Michiel van Haarlem, the head
RIWKH1HWKHUODQGV6.$RIƅFH
“That’s why the decision was made to build
both SKA-Mid in South Africa and SKA-Low in
Australia.”

Where is the ‘square kilometre’?
SKA may be vast, but it doesn’t technically
live up to its name… yet
SKA director Phil Diamond
admits that ‘Square Kilometre
Array’ is a bit of a misnomer.
The 197 dish antennas of
SKA-Mid in South Africa have
a total surface area of
33,000m2 (0.033km2). The
effective receiver surface area
of the dipole antennas of
SKA-Low in Australia can be
calculated with a complicated
formula that is dependent on
the observing frequency; it’s

in the order of 0.4km2 .
However, the name ‘Square
Kilometre Array’ was
conceived in the late 1990s,
with the future second phase
of the facility in mind, which
will have 10 times the number
of dishes and antennas. “If
that second phase will indeed
be realised in the future, we
will easily reach a total
surface area of one square
kilometre,” says Diamond.

62 BBC Sky at Night Magazine March 2024

Even with 131,072 dipole
antennas, SKA won’t reach
its advertised size

S Forerunners
of the SKA,
the Westerbork
Synthesis Radio
Telescope (left),
completed in 1970,
and the Very Large
Array (right), going
strong since 1976

ILLUSTRATION

S The SKA will

transform our
understanding
of (clockwise
from bottom
left) transient
phenomena like
fast radio bursts;
hydrogen from the
cosmic dawn; how
galaxies are born;
and planets form

Laying the groundwork
$WERWKVLWHVUDGLRDVWURQRP\LVDOUHDG\ƆRXULVKLQJ
The MeerKAT observatory, consisting of 64
13.5-metre radio dishes, is operational in the Great
Karoo, about 100km north of the small town of
Carnarvon. Eventually, MeerKAT will become part of
6.$0LG0HDQZKLOHWKH$XVWUDOLD6.$3DWKƅQGHU
$6.$3 DQGWKH0XUFKLVRQ:LGHƅHOG$UUD\ 0:$ 
are two further ‘SKA precursors’, located in an
uninhabited area of Western Australia. “All these
precursors do a fantastic job,” says Diamond, “but we
will become much more sensitive.”
This extreme sensitivity is the result of the huge
number of individual receivers: 197 radio dishes
in South Africa and no less than 131,072 personhigh, Christmas-tree-shaped antennas in Western
Australia. The 197 dishes of SKA-Mid (the 64
MeerKAT dishes plus 133 slightly larger 15-metre
dishes built in China) will be distributed over an area
150km across, with the largest concentration in the
core of the interferometer. This maximum baseline
determines the observatory’s angular resolution.
SKA-Low in Western Australia will have a
comparable layout, with some 70 per cent of the 512
‘stations’ (each consisting of 256 ‘Christmas trees’)
in the central part and a (preliminary) maximum
baseline of 75km. According to André van Es, senior
project leader of the Australian part of SKA, the core

of SKA-Low lies some 30km west of the existing
ASKAP array.
ş7KHƅUVWVWDWLRQVZLOOEHFRPSOHWHGLQŠ
says van Es. “As soon as 10 per cent of SKA-Low is
realised, we will already be the world’s most sensitive
observatory in this part of the radio spectrum.”
Similarly in the case of SKA-Mid, as more radio dishes
are added over the coming years, the interferometer
will become ever more sensitive and keen-eyed.

Scientific challenges
Thanks to its high sensitivity, SKA will be able to
map the distribution of neutral hydrogen in galaxies
hundreds of millions or even billions of lightyears
away. This will shed light on their structure and
dynamics, but also on the evolution of galaxies in
general. Closer to home, the birth process of stars and
planets can be studied in detail, and SKA will create
WKHƅUVW'PDSRIPDJQHWLFƅHOGVLQWKH8QLYHUVH
both within and beyond our Milky Way galaxy.
The new observatory will also study the evermysterious fast radio bursts. Detailed observations
of these powerful explosive events should provide
information on the distribution of charged particles
in intergalactic space. And precision measurements
of pulsars (rapidly spinning neutron stars) will reveal
very-low-frequency gravitational waves: minute
ripples in spacetime produced by supermassive binary X
March 2024 BBC Sky at Night Magazine 63

North stars
Some of the current and future top radio observatories in the Northern Hemisphere

(Five-hundred-meter Aperture Spherical Telescope)

(Low-Frequency Array)

A huge radio dish, built in a natural bowl-shaped valley in
Pingtang County, Guizhou, southwest China. With a surface
area of 0.2km2, FAST is currently the most sensitive radio
telescope in the world. (The 300-metre Arecibo radio
telescope in Puerto Rico collapsed in late 2020; the Green
Bank Telescope in West Virginia and the German Effelsberg
Telescope have diameters of approximately 100 metres.)

An array of some 20,000 dipole antennas, spread over seven
European countries, with the core in the northeast of the
Netherlands. Thanks to its long baselines of more than
1,000km, LOFAR has a larger angular resolution than SKA-Low,
which will operate at comparable low radio frequencies.
However, SKA-Low will be much more sensitive. “LOFAR was a
real pioneer,” says former LOFAR director Michiel van Haarlem.

SIPA US/ALAMY STOCK PHOTO, LOFAR/ASTRON, NRAO, THE DEEP SYNOPTIC ARRAY
PROJECT, RYTIS BERNOTAS/ALAMY STOCK PHOTO, SKAO

ILLUSTRATION

LOFAR

ILLUSTRATION

FAST

ngVLA

DSA-2000

(Next Generation Very Large Array)

(Deep Synoptic Array)

This future facility will be more than 10 times as sensitive as
the current VLA observatory in New Mexico. The plan is for 244
radio dishes with diameters of 18 metres, supplemented with 19
smaller 6-metre dishes, distributed across large parts of the
USA. ngVLA will fill the gap between observations by SKA (at
relatively long wavelengths) and by the ALMA observatory in
Chile, which studies cosmic microwave radiation.

A future array of no less than 2,000 small, simple antennas
with diameters of 5 metres, in the remote Hot Creek Valley in
Nevada. A 110-antenna prototype is under construction in
California. DSA-2000 will be able to quickly map the whole
visible radio sky. By carrying out such surveys on a regular
basis, astronomers hope to discover many short-lived
transient phenomena, such as fast radio bursts.

X

black holes in the cores of remote galaxies. One of
the outstanding challenges for SKA is the detection
of the so-called EoR signal (Epoch of Reionisation).
A few hundred million years after the Big Bang, the
QHZERUQ8QLYHUVHZDVƅOOHGZLWKWHQXRXVQHXWUDO
hydrogen gas. During these ‘dark ages’, the hydrogen
atoms emitted radiation at a radio wavelength of
21cm. But because of cosmic expansion, this radiation
arrives at Earth with a much longer wavelength – a

64 BBC Sky at Night Magazine March 2024

phenomenon known as redshift. SKA-Low should be
able to observe this ancient, weak radio signal.
7KRVHFRVPLFGDUNDJHVHQGHGZKHQWKHYHU\ƅUVW
stars were formed. During the Epoch of Reionisation,
the neutral hydrogen was ionised again by the
HQHUJHWLFUDGLDWLRQRIWKHƅUVWVWDUV RUPD\EHWKH
YHU\ƅUVWEODFNKROHV %\REVHUYLQJDWGLIIHUHQW
wavelengths, astronomers will measure radio
waves from neutral hydrogen at different redshifts,

ILLUSTRATION

ILLUSTRATION

Science goals include
hunting down radio signals
from intelligent civilisations
elsewhere in the Universe

S Dish wish list:
project leaders
want to eventually
see 2,000 radio
dishes erected
across Africa

corresponding to varying distances and epochs in
cosmic history. Thus, the EoR signal can be followed
through cosmic time, revealing when and how the
cold gas was heated and ionised again.
Finally, the reams of data produced by SKA will also
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PXFKOHVVH[FLWLQJLI\RXNQHZHYHU\WKLQJLQDGYDQFHŠ

Data deluge
Govert Schilling is
an astronomy writer
and the author
of Ripples in
Spacetime

According to Rosie Bolton, who coordinates the data
ƆRZLQIUDVWUXFWXUHIRUWKH6.$2EVHUYDWRU\WKH
future facility will produce humongous amounts of
VFLHQFHGDWDş:HZLOOREVHUYHDKXJHSDUWRIWKHVN\
DWGLIIHUHQWIUHTXHQFLHVŠVKHVD\Vş(DFKUDGLR
ŜSLFWXUHŝFRQWDLQVDIHZKXQGUHGWHUDE\WHVŠ
That’s after a drastic data reduction: SKA-Mid

DQG6.$/RZZLOOSURGXFHWHUDE\WHVDQG
terabytes of raw data per second, respectively.
Because of technical bottlenecks in data transport
DQGVWRUDJHWKHVHGDWDƆRZVKDYHWREHUHGXFHGWR
some 12 gigabytes per second.
ş:HMXVWFDQŝWVWRUHHYHU\WKLQJŠH[SODLQV%ROWRQ
ş7KHUHIRUHDUDSLGLQLWLDOGDWDDQDO\VLVRFFXUVULJKW
after observations take place. A lot of data will be
discarded, but still more than enough remains to
IDFLOLWDWHUHYROXWLRQDU\VFLHQFHŠ%RWK6.$ORFDWLRQV
will yield approximately one petabyte (one billion
PHJDE\WHV SHUGD\IRU\HDUVRQHQG
:KHQFRQVWUXFWLRQRIWKHODUJHVWDVWURQRPLFDO
observatory in history is completed, which is likely to
be within a few years, astronomers hope that won’t
be the end of the story. Ever since the early days of
WKHDPELWLRXVSURMHFWWKHUHKDYHEHHQSODQVIRUD
second phase (sometimes called SKA2) that would
EHWLPHVDVSRZHUIXO
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UDGLRGLVKHVLQ$IULFDDQGPRUHWKDQDPLOOLRQ
dipole antennas in Australia, distributed over a much
larger area in both cases. Although Diamond doesn’t
want to speculate about the feasibility of this second
phase (the current observatory already has a price
WDJRIPRUHWKDQŲEQ şZHFHUWDLQO\KDYHQŝWJLYHQ
XSRQWKHSODQVŠKHHQWKXVHV
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Telescope. As soon as a new observatory starts to
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WDNHWKHQH[WVWHSŠ
7KLVLVDFRQGHQVHGYHUVLRQRIDVWRU\WKDWƅUVW
appeared in the Flemish magazine Eos
March 2024 BBC Sky at Night Magazine 65

The edge of the
Melissa Brobby looks at what lies at the outskirts of our Solar System

B

eyond the Solar System lie cold,
dark and vast regions that were
once shrouded in mystery. It is here
that we have discovered various worlds,
objects left over from the early days
of the Solar System, a barrier that shelters us from
KDUPIXOLQWHUVWHOODUSDUWLFOHVDQGDJLDQWFORXGƅOOHG
with icy objects. Right now, NASA’s Voyagers 1 and 2,
and the New Horizons spacecraft are travelling into
these uncharted territories, giving us a glimpse into
the realms beyond our cosmic neighbourhood. Here
we take a look at the regions found at the edge of
our Solar System.

Sa

tu

rn

A

st

er

o

id

be

Melissa Brobby
is a science
communicator
and space writer

n
Ve

M

us

ar

SU

N

nu

The Kuiper belt

66 BBC Sky at Night Magazine March 2024

cu

ry
Ea

rt

h
J

i
up

te

r

N
a
Ur

The Kuiper belt is a huge ring-shaped
region beyond the orbit of Neptune. The
main belt spans from 30 to 50 AU, with a
more sparse, scattered disc stretching
out to 1,000 AU. It’s made up of dwarf
planets, comets and bits of rock and
ice, and is like the asteroid belt but
20 to 100 times more massive. So far,

er

s

Solar System
(planets not
to scale)

MARK GARLICK/SCIENCE PHOTO LIBRARY/ISTOCK/
GETTY IMAGES, NASA/JPLCALTECH

la

lt

M

ILLUSTRATION

So

t
ep

un

e

s

A frigid realm where Pluto resides

more than 2,000 Kuiper belt objects
(KBOs) have been catalogued, but this
number may just scratch the surface
as it’s estimated there are hundreds of
thousands of larger objects that are at
least 100km in diameter or larger.
Many KBOs have moons or much
smaller bodies orbiting them. Pluto, Eris,

Haumea and Quaoar are all KBOs that
have their own moons. NASA’s New
+RUL]RQVZDVWKHƅUVWVSDFHFUDIWWR
visit an object in the Kuiper belt when
LWƆHZE\3OXWRDQGLWVPRRQVLQ
EHIRUHJRLQJRQWRƆ\E\DVHFRQG.%2
Arrokoth, in 2019, located 1.6 billion
kilometres beyond Pluto.

ys
rS

te

m

The Oort cloud The origin of long-distance comets
Far beyond Pluto lies the Oort cloud, which is
theorised to be a giant bubble that surrounds
the Sun, planets and Kuiper belt, and is made up
of billions, if not trillions, of bodies ranging from
comet-like objects to potential dwarf planets.
It’s named after Dutch astronomer Jan Oort,
who proposed the existence of the cloud to
explain the origin of long-distance comets that
travel in from all directions instead of along the
same orbital plane as the planets. Notable objects
thought to have travelled from the Oort cloud into
the Solar System include comet Hale–Bopp, which

passed within 197 million kilometres of Earth and
was visible to the naked eye in 1996 and 1997, and
Halley’s Comet, which travels backwards around
the Sun every 76 years and was last seen
in our skies in 1986.
The Oort cloud is incredibly far away. According
to NASA, its inner edge is located between 2,000
and 5,000 AU from the Sun (1 AU being about 150
million kilometres), while its outer edge is possibly
between 10,000 and 100,000 AU, nearly half the
distance between the Sun and the closest star to
our own, Proxima Centauri.

i
Ku

The heliosphere
A magnetic bubble protecting
our Solar System
Termination
shock
Voyager 1

ILLUSTRATION

Voyager 2

Heliopause

The heliosphere is a giant bubblelike region that surrounds the
Solar System as it moves through
space. It’s formed by a constant
ƆRZRIFKDUJHGSDUWLFOHVVHQW
out by the Sun that spreads out
to just beyond the Kuiper belt,
before being obstructed by the
interstellar medium, creating a
giant bubble around the Sun and
planets that acts as a protective
shield against cosmic radiation.
The heliosphere has several
different features. The termination
shock is where the solar wind
slows down and begins to interact
with the interstellar medium
around 75 to 90 AU from the Sun.

p

b
er

el

t

The heliosheath is a region where
the solar winds travel slower
and compress to become hot
and dense. Finally, there is the
heliopause, the outer edge of the
heliosphere, where the solar wind
meets the interstellar medium.
NASA’s Voyagers 1 and 2 are the
ƅUVWKXPDQPDGHVSDFHFUDIWWR
cross the heliopause – when they
were around 90 AU from Earth
– and enter interstellar space
(in 2012 and 2018, respectively).
However, it will take the twin
spacecraft about 300 years to
reach the Oort cloud and they
won’t exit its outer edge for
another 30,000 years.

March 2024 BBC Sky at Night Magazine 67

at the dawn of

artificial intelligence
As ever more ambitious space surveys
begin to create unprecedented mountains
of data, Paul Fisher Cockburn asks if the
future of astronomy will be found in AI

A

ILLUSTRATION: MONSITJISTOCK/GETTY IMAGES

s the late Douglas Adams wrote in
The Hitchhiker’s Guide to the Galaxy,
“Space is big. Really big. You just
won’t believe how vastly, hugely,
mindbogglingly big it is.”
And, to be fair, he wasn’t wrong.
For astronomers – especially those focusing on
cosmology – this has one obvious consequence.
The more detailed and accurate their studies of
such a “really big” cosmos become, the larger the
amount of data they are likely to generate – and
have to process. Arguably this has been a looming
SUREOHPHYHUVLQFHDVWURQRPHUVƅUVWVWDUWHGVWLFNLQJ
cameras onto their telescopes, but the latest
digital technologies have pushed the issue to the
foreground like nothing else before. X

Too much information?
:LWKDJDUJDQWXDQƆRRG
RIVSDFHGDWDRQLWVZD\
scientists face the Herculean
WDVNRIDQDO\VLQJLWDOO

68 BBC Sky at Night Magazine March 2024

March 2024 BBC Sky at Night Magazine 69

ESA/EUCLID/EUCLID CONSORTIUM/NASA. BACKGROUND GALAXIES: NASA/ESA AND S. BECKWITH (STSCI) AND THE HUDF TEAM, ESA,
ESO/M KORNMESSER/VPHAS+ TEAM. ACKNOWLEDGEMENT: CAMBRIDGE ASTRONOMICAL SURVEY UNIT, EUCLID CONSORTIUM

ILLUSTRATION

Move over, Hubble:
Euclid will send back more
data in one day than the
veteran telescope has
done over its entire life

X Take the Square Kilometre Array, featured earlier
in this month’s issue. Once it’s fully operational, it will
create terabytes of data every second.
The latest European Space Agency (ESA) mission,
the Euclid space telescope (launched on 1 June 2023),
is another prime example. Its mission is essentially
an attempt to measure the geometry of the entire
Universe, improving our understanding of dark matter
and dark energy. It requires the incredibly precise
observation of billions of stars and galaxies. The
amount of data that the mission will generate during
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“What I think is interesting is that no human will
look at all the Euclid data. It’ll be too big, it’ll never
happen,” explains Andrew N Taylor, professor of
astrophysics at the University of Edinburgh. “There’s a
good chance that if anyone picks on a random piece
of sky, no other human will have ever looked at that
bit of sky in such detail before.”

Information overload
Andrew has been part of the ESA’s Euclid Consortium,
which runs the space telescope, for almost 20 years,
helping devise the initial concept, the design of the
mission and its science goals. During the last 10
years, as the telescope and its various optics and
detectors were designed, built and tested before
launch, his focus – along with many others’ – shifted
towards data analysis.
“Euclid produces an enormous amount of data,”
he says. “We’re downloading hundreds of gigabytes
of data per day. Just to give you an idea of the
volume, a good analogy is what is seen from the
Hubble Space Telescope. In terms of image quality,
a single image from Euclid and an image from Hubble
are very similar, but if you put together all of the
pictures Hubble’s taken during its lifetime and laid
them on the sky, it would cover an area only about
20 times the size of the full Moon. Euclid can do the
70 BBC Sky at Night Magazine March 2024

Portions of the sky covered
by Euclid’s Wide Survey

Euclid Deep Fields
(10 per cent of
observations)

Excluded region (due to obstructions
such as Milky Way stars)

S Euclid’s plan
of attack is
breathtaking,
surveying more
than one-third
of the sky

equivalent of what Hubble has done, in its lifetime,
in a single day. In fact more, because it takes not just
optical images like Hubble, it also takes ones in the
infrared and spectra of the galaxies and objects out
there. It’s just a huge step up for astronomy in the
amount of information that we’re going to get.”
This isn’t just because the multinational Euclid
team wanted to go out and collect lots of data.
ş7KHVFLHQWLƅFJRDOLVWRWU\WRXQGHUVWDQGWKHQDWXUH
of dark matter and the dark energy Universe, and
in order to test our theories we know we’ve got to
look for very subtle little differences in things like
the distribution of matter and its evolution in the
Universe,” he says. “It’s the classic large data problem:
we’ve got a very small signal, so we need a huge
dataset to try to get the levels of precision we need
to test our theories.”
In order to process the data, the Euclid Consortium
has developed both bespoke computer algorithms, to
assist with data compression, and an IT infrastructure

1. Detector

5. Matching
background level

S Stages in a
data ‘pipeline’
that wrangles
unmanageably
large raw data into
images astronomers
can interpret

2. Raw data

6. Manually cleaning
artefacts

3. Reduced data

4. Building a mosaic

7. Assigning colours
WRHDFKƅOWHU

8. Final colour image

‘pipeline’ that takes the raw data and turns it into
something astronomers can actually use and
interpret. The techniques used are all based on the
same traditional methods used by astronomers for
hundreds of years, but the scale of the work requires
a novel approach. Although all the data from Euclid
will initially be received at the European Space
Astronomy Centre near Madrid, that won’t be where
it’s processed.
Work on the Euclid data will be carried out in nine
science data centres across Europe, the UK centre
being at the Royal Observatory Edinburgh. “The
original concept,” says Taylor, “was that each of the
countries would take responsibility for one area of
processing, and that the data would move around
the countries. Pretty early on, we realised this was not
feasible; the solution we came up with was that we’ll

An early Euclid test image
showing how algorithms sift
unwanted artefacts from the
bits researchers need

split the sky up into ninths. Every data centre is doing
all of the processing for their own patch of the sky.”

Break it down
That processing will entail transforming the individual
images into ‘catalogues’. Algorithms will detect
particular features the Euclid team are interested
in, such as stars and galaxies, and then create lists
of their positions, sizes and other properties. It will
only be at that point, when the data is of a more
manageable size, that each of the data centres
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compiling and processing.
This is not without its challenges. “One of the
things we’ve had to deal with,” explains Taylor, X

Finding the ‘weird’
When it comes to spotting strange things in the data, humans are far better than machines
Can machine learning and AI
help detect the unexpected in
astronomical datasets? Alex
Andersson, a researcher at the
University of Oxford, believes
it might.
“You can look at certain
models of physics, like how
stars work or galaxies behave,
and so have things that you
can predict but haven’t seen
yet – the sort of ‘known
unknowns’,” he says. “And then
there’s the ‘unknown
unknowns’. I spend a lot of
time working on anomalydetection algorithms, where I
try not to assume much about
the physics or what I’m
expecting, and just see what
the data says and what comes
out that looks ‘weird’.”
All Andersson’s work
involves MeerKAT in South
Africa, the radio telescope

People power: rare quasar
ionisation echoes discovered
by Dutch schoolteacher
Hanny van Arkel

that will form the core of the
Square Kilometre Array (SKA).
Alongside this, he runs a
citizen science project called
‘Burst from Space MeerKAT’
on the Zooniverse platform,
asking hundreds of online
volunteers to search the
telescope’s data for unusual
features. Similar citizen
science projects have helped

other astronomical surveys
wade through vast amounts of
data. Repeatedly, these
volunteers have been fantastic
at picking out the weird,
out-of-place things in images
that can lead to new
discoveries. One of the earliest
examples is from Zooniverse
project Galaxy Zoo, where
helpers found strange green

blobs that turned out to be
compact galaxies.
But the data from Euclid and
SKA will be too huge even for
teams of citizen scientists to
handle. Could AI be trained to
search for those unknown
unknowns? Andersson is
testing just such anomalydetecting algorithms on the
same data his citizen scientists
are trawling through, seeing if
it will uncover those same
‘weird’ objects. His goal,
though, is not to replace the
citizen scientists, but rather to
use AI to reduce the data to a
more manageable size for
them to take on.
“I personally think that
discovery in the Universe is a
uniquely human experience,
so I don’t think that machine
learning will replace us in that
regard,” he says.

March 2024 BBC Sky at Night Magazine 71

Artificial intelligence
AI trains computers to think like a human
Arguably, 2023 was the year
that artificial intelligence (AI)
really gained mainstream
attention, inspiring – like any
technological advance
throughout human history
– both evangelical enthusiasm
for its potential benefits and
apocalyptic horror at its
likely downsides.
Yet AI has been around for
much longer than the likes of
ChatGPT. The term itself was
first coined back in 1956, and
scientists have been working
on ways for computers to
‘think’ and respond to us in a
more ‘human’ way since at
least the 1960s. Without us
even noticing, much of our
modern life today relies on AI,

Siri, how much dark
matter is there in
the Universe?

whether it’s your social media
activity, Netflix viewing
choices or digital home
assistants like Alexa and Siri.

X

“is how do you make everything the same when
the underlying computer infrastructure might not
be. So there’s a lot of what we call virtualisation,
which is that we try to emulate the same computer
everywhere.”

Rise of the machines
While this ‘distributed’ model is in part inevitable
within a multinational organisation like ESA, it means
the Euclid team have unexpectedly become pioneers
in how to carry out massive computing projects
on distributed networks, and have already been

approached by large companies interested in how
they did it. It’s not just astronomers that have
to process big datasets, after all.
With all this talk of IT systems and algorithms,
how important are people when it comes to the
data processing?
“We’re certainly entering an age where it seems
computers can do more and more, and take over
more and more things,” says Taylor. “I think [Euclid]
was at a lucky phase, in the sense that we’ve
been working on this for nearly 20 years. The real
algorithm-writing started only about 10 years ago.”

S Training at Goddard Space Flight Center as NASA races to

embrace the challenges and opportunities of the new technology

72 BBC Sky at Night Magazine March 2024

It’s all about making our
technology appear to act in a
more responsive way, a
principle that can be employed

in several different ways. One
of the biggest advancements
has been in the subfield of
machine learning, where
increasingly sophisticated
software algorithms enable
machines to remember their
mistakes and learn from them,
instead of just repeating
whatever tasks they’ve been
programmed to carry out.
Many of the concerns
around the technology are
based on a computer’s ability
to carry out many tasks
– especially computations
– far faster than humans. With
astronomers facing ever larger
datasets, however, it’s likely
machine learning will become
a commonly-used tool.

S Workshops on AI and machine learning have been showing how
automation will revolutionise data science across the agency

ILLUSTRATION

No human could ever look
at all of Euclid’s data;
people-guided algorithms
must ultimately do the job

There are also, however, some newer methods being
XVHGRQ(XFOLGGDWDVXFKDVDUWLƅFLDOLQWHOOLJHQFH $, 
the technique of using computer programs that mimic
how humans think. One particular subset of AI used in
astronomy is ‘machine learning’, where programs learn
from experience as they process the data, improving
their analysis over time.
Currently, Euclid uses these newer tools in a limited
way, such as helping to classify galaxies. “The
tendency was to go with things that were understood,
and had been shown to be reliable on previous
projects,” says Taylor. “A lot of things are being done
more traditionally – for ‘robustness’, for reliability.”

Keeping people in the picture

Paul Fisher
Cockburn is a
science and
astronomy writer

At the moment, astronomers are only just receiving
the data and so are still in the early stages of
processing it. As they proceed to more advanced
stages of analysis, they will eventually start wanting
to compare the data with what their theories predict
– one of the main methods astronomers use to test
their ideas about how the Universe works.
“One of the issues there, is how you generate
the theoretical models,” explains Taylor. “For the
detailed analysis, we do want to have simulations
of the Universe based on different theories of
what’s going on. It’s a very expensive thing to run
a whole simulation, so there’s a lot of work going
LQWRWU\LQJWRXQGHUVWDQGLIZHFDQXVHDUWLƅFLDO
intelligence or machine learning to provide shortcuts
– not to lose precision or accuracy, but to provide
rapid ways of doing it.”

Ultimately, Taylor accepts that the volume of
data being produced by Euclid will encourage the
increased usage of machine learning, the automation
of the Euclid data processing. But he sees
astronomers – people – very much still at the centre
of what’s going on.
“At the moment, even though we’ve now got a
pipeline and analysis in place that does this, the
algorithm development was all done by people, using
their knowledge and understanding of the problems
to process these sorts of datasets,” says Taylor.
“It’s not just a case of ‘Let’s have some AI look
at the images and it’ll tell us the answers’, because
there are lots of details in the images that you need
to understand.”
One of the characteristics of AI programs is that
they need data in order to learn. At the moment,
AI doesn’t know what Euclid data looks like, as the
spacecraft has only just begun its mission to survey
the sky. Even once AI does begin to process the
data, it will still require human input to understand
what it’s looking at and to begin teaching it its
ƅUVWOHVVRQV
“There’s a huge amount of detail to go through
and really understand,” comments Taylor. “And it’s
people who bring that knowledge.”
The issues around handling Big Data are only going
to grow over time. It’s only via a team effort
– using both processing tools such as AI and teams of
humans spread across the world – that astronomers
will be able to work together towards a better
understanding of the Universe around us.
March 2024 BBC Sky at Night Magazine 73

ANTONIO_DIAZ/ISTOCK/GETTY IMAGES, SEAN KEEFE/NASA GODDARD X 2, ESA

“Even though we’ve now got a pipeline and analysis in
place, the algorithm development was all done by
people, using their knowledge and understanding”

Practical astronomy know-how for every level of expertise

SKILLS FOR STARGAZERS
Setting up a Go-To altaz mount
Take the time to get it right – the results will be worth it
improve the Go-To and tracking
performance of your altaz
system if you pay a little more
attention to the initial setup of
your mount and tripod.

Level up

ALL PICTURES: PAUL MONEY

W

e all want to get the best out
of our equipment. Whether it’s
equatorial or altaz, your Go-To
system will work at its best if you
pay attention to how you initially
set up your tripod, mount, telescope and accessories.
Equatorial mounts need precisely aligning with
the north celestial pole and that can add additional
complications, including the polar alignment
process, the weight of the equipment and what
counterweights are needed to achieve good, and
indeed great, Go-To results.
However, altaz Go-To mounts offer a simpler
solution to your observing and, to a lesser extent,
your imaging needs. Gone is the complicated
nature of the polar alignment and the need for
counterweights; instead, as long as the mount and
tripod are set level with your horizon, you can enjoy
an observing or lucky imaging session for as long as
your clear night sky lasts. However, you can greatly

74 BBC Sky at Night Magazine March 2024

S Altaz Go-To

mounts are
beginner-friendly,
and great for
observing and
astrophotography
– but only if they’re
set up properly

It’s easy to think that if you have Paul Money is an
astronomy writer
simply placed the mount and
and broadcaster,
tripod down, without paying
and BBC Sky at
much attention to it except for a
Night Magazine’s
rough levelling of the setup, that reviews editor
performing a Go-To alignment
will take care of any errors. But take a little more care
and patience here and your night under the stars will
be more productive, satisfying and useful. Once you
become familiar with setting everything up carefully
and with a little more thought, it will become second
nature every time you get that rare clear patch of
night sky to take advantage of.
It’s especially useful if you can choose a location in
your garden that you can repeatedly use. By marking
out the positions for the tripod legs, you can do the
setup once and, if you need to put your equipment
away between sessions, you can return to the exact
same place time after time. This enables you to use
the hibernate function of your chosen mount to pick
up from where you left off. The good news is that this
is independent of the make of the mount/tripod, as
almost all of them require a level setup with the initial
or home position of the telescope pointing north.
Paying attention to levelling the tripod and
rechecking this once the mount and telescope are
attached, along with knowing where true geographic
north is from your chosen location, will make setting
up a breeze for future sessions. Follow our simple
step-by-step guide to getting the best out of your
altaz Go-To system.

What you’ll need
X Altaz Go-To Mount, tripod, suitable telescope
X Handset (or smartphone and app)
X Power tank, compass, spirit level
X A suitable location to set up

Step by step
Step 2

Step 1
Using a compass, locate north for your observing site. Set up the
tripod assembly on firm ground, ensuring that one leg is pointing
towards north. Spread out the legs for stability and adjust to a
comfortable height suitable for the user.

Use a spirit level, or
else the tripod’s
own in-built bubble
level, to level the
tripod. This ensures
that the azimuth
corresponds
precisely to your
horizon, ignoring
anything cluttering
it such as trees,
houses or hills. With
this done, your
mount is correctly
set up for when you
perform a star
alignment.

Step 3

Step 4

Attach the mount
to the tripod,
orientated so that
when the telescope
is added in the next
step it will be
pointing exactly
northwards. Don’t
over-tighten the
mount at this stage,
in case you need to
make minor
adjustments to
refine its position
later in Step 6.

Attach a suitable
telescope via the
saddle on the side
of the mount and
affix it firmly in
place. Ensure the
telescope is set
level and pointing
northwards,
adjusting if
necessary. In most
cases this is the
initial ‘home’
position you’ll use
when beginning the
star-alignment
procedure.

Step 6

Step 5
Make sure you’re using fresh batteries. Alternatively, connect a
suitable powerpack and adaptor using the power port on the
mount head. Attach the handset and turn power on, or power up
and connect to the mount’s Wi-Fi network with your smartphone.

As a final check,
once it’s dark
manually point the
telescope up at
Polaris to check
that you’re
precisely pointing
north. Make any
adjustments to the
azimuth that are
needed, then set it
back to level. You
can now begin the
alignment process
to achieve accurate
Go-To navigation to
your targets.

March 2024 BBC Sky at Night Magazine 75

Take the perfect astrophoto with our step-by-step guide

ASTROPHOTOGRAPHY

Clair-obscur effects
There’s a knack to photographing lunar tricks of the light. Here’s how to do it

ALL PICTURES: PETE LAWRENCE

L

unar clair-obscur
effects are tricks
of the light
that produce
recognisable
shapes on the Moon’s
surface. They occur when
jumbled areas of light and
shadow produce something
that looks familiar. Most
occur near the terminator
and fade into and out of
view in a few hours.
This isn’t true for all
clair-obscur effects, though.
The L-Shaped Mountain, for
example, is visible on the
waning gibbous Moon under
direct lighting away from the terminator for many
days. It occurs when the steep sides of a mountain to
the west of crater Lamèch become fully illuminated
to form a bright letter ‘L’.
Others such as the popular Lunar X and V fall under
the transient category. As the light of the lunar dawn
hits the regions in which they form, recognisable
patterns slowly create a capital X and V. At optimum
illumination they look impressive and are pretty easy
to recognise, causing you to question why you hadn’t
noticed them in the past. This isn’t always the case,
though, and some are very obscure!
7KH/XQDU;DQG9IRUPDURXQGWKHWLPHRIWKHƅUVW
TXDUWHU0RRQVSHFLƅFDOO\ZKHQOXQDUFRORQJLWXGHLV
358°. Lunar co-longitude indicates the position of the
morning terminator and is measured in degrees from
when it crosses the Moon’s central meridian. Its value
is near 0°DWƅUVWTXDUWHULQFUHDVLQJWRQHDU° at full
Moon, near 180° at last quarter and near 270° at new
0RRQ7KHŜQHDUŝTXDOLƅFDWLRQLVEHFDXVHWKH
GHƅQLWLRQVRIWKHVHSKDVHVGHSHQGRQWKH0RRQŚ
(DUWKŚ6XQDQJOHDQGDQREVHUYHURQ(DUWKVHHV
slightly different illuminations depending on location.
$VWKHƅUVWTXDUWHU0RRQLVDSRSXODUSKDVHIRU

76 BBC Sky at Night Magazine March 2024

S The L-Shaped

Mountain (left) is
one example of a
long-lived clairobscur effect,
visible for several
days, while the
Lunar V (right, top)
and Eyes of Clavius
(right, bottom) are
more time-sensitive
and fleeting

photography, your images
may contain the X and V
without you realising.
Imaging clair-obscur
effects is relatively easy.
A smartphone can record
a large effect such as the
Jewelled Handle. A DSLR
or equivalent setup with
a 1,000mm or longer lens
or telescope can show many
more. A high-frame-rate
planetary imaging setup
should be able to capture
all of them.
But of course there is a
catch. In order to record the
transient effects, you’ll need
the Moon above the horizon at the correct time and
the weather will need to comply. Timings don’t always
favour dark skies, but clair-obscur effects can be seen
fairly well even in daylight. For those using a mono
KLJKIUDPHUDWHFDPHUDDQLQIUDUHGSDVVƅOWHUFDQ
darken daylight to produce high-contrast images.
However you do it, capturing clair-obscur effects is
an interesting way to get familiar with the Moon and
the ‘chase’ element introduced by time-sensitive
shadow play can add extra excitement. If you
become adept at capturing static results, consider
recording a timelapse of how the effect forms. This
can be tricky as you’ll need a clear view of the Moon
for many hours. As we head towards spring, the early
phases of the Moon are well presented and high in the
sky for long periods of time, making this a perfect
time to give it a go.
Equipment: DSLR or equivalent with 1,000mm or
longer lens or telescope, or a planetary imaging setup

Pete Lawrence is an
expert astro-imager
and a presenter on
The Sky at Night

Send your images to:
gallery@skyatnightmagazine.com

Step by step
Curtiss’s Cross
3 March, 06:00 UT
Co-longitude 183 °

Nessie
18 March, 00:01 UT
16 April, 12:46 UT
Co-longitude 2.9 °

Lunar X & V
17 March, 14:21 UT
16 April, 03:08 UT
Co-longitude 358°

Eyes of Clavius
18 March, 19:55 UT
Co-longitude 13 °

Face in
Albategnius
17 March, 22:14 UT
16 April, 11:00 UT
Co-longitude 2.0°

Star-Tip
Mountain
22 March, 02:25 UT
Co-longitude
52.8°

Stars of Aristillus
16 April, 16:54 UT
Co-longitude 5°
Jewelled Handle
18 April, 18:07 UT
Co-longitude 30°
Cutlass
1 May, 03:37 UT
Co-longitude 181°

STEP 1

STEP 2

Pick your target and make plans for capturing it. A few upcoming
events are listed above and we publish predictions in our Sky
Guide every month, but there are others out there too. There’s an
excellent list at the-moon.us/wiki/Clair-obscur; you may have to
research the best co-longitudes that the effects become visible.

Lunar co-longitude can be determined from a number of
sources. Try the ephemeris section of Virtual Lunar Atlas at ap-i.
net/avl/en/start or WinJUPOS jupos.org/gh/download.htm (both
are freeware). Determine the time and date of an effect, make
sure the Moon will be visible and keep an eye on the weather.

STEP 4

Handheld smartphone
shot of the Moon,
just about showing
the Jewelled Handle
(arrowed)

If using a planetary
imaging setup,
clair-obscur
effects that reach
optimum visibility
in daylight skies
will benefit from
the use of a mono
high-frame-rate
camera fitted with
an infrared pass
filter to darken the
sky. Aim to capture
around 1,000
frames and
process as you
would normally for
a lunar surface
shot, using a
registrationstacking program
such as
AutoStakkert!

100mm refractor (focal
length 920mm) using a DSLR

STEP 3
How will you capture the effect? Large effects may be recorded
with certain smartphones, but smaller ones require a DSLR or
equivalent with a long-focal-length lens, say 1,000mm, or else a
planetary imaging setup. Putting a smartphone up against the
eyepiece of a telescope (afocal photography) works too.

STEP 5

STEP 6

Consider taking shots at around 30-minute intervals from at
least 2–4 hours before optimum appearance. This will provide
you with a set of images showing the effect at different stages of
formation and allows you to pick the best result for presentation.
Remember to add date/time and equipment details to the images.

If you obtain several images in the run-up to and after optimum
appearance, these can be aligned in a layer-based editor and
then turned into an animated GIF showing how the feature forms
over time. The success of this will hinge on image scale, closeups showing more shadow movement than wide-angle shots.

March 2024 BBC Sky at Night Magazine 77

CAUTION
When observing
atmospheric optics,
always block the Sun
with your hand, a roof
or a tree. NEVER look
through a camera
YLHZƅQGHUSRLQWHG
towards the Sun

Expert processing tips to enhance your astrophotos

ASTROPHOTOGRAPHY

Atmospheric optical phenomena
How to process your images to reveal haloes, arcs, sundogs and moondogs

ALL PICTURES: MARY MCINTYRE

A

lmost everybody has
seen a rainbow, but far
fewer people have seen
any kind of atmospheric
optics display, despite how
frequently they occur. These haloes and
arcs form when sunlight (or moonlight)
is refracted through tiny hexagonal ice
crystals in cirrus clouds, which are found
at an altitude of around 5–10km. The
light gets refracted on the way in and
again on the way out of the ice crystals,
and this causes the light rays to deviate
and disperse to form the haloes and arcs.
Some arcs exhibit colour separation, while
some are white.
Atmospheric optics are beautiful
and fascinating to observe. Although
photographing them can be challenging
because of the Sun’s glare, cameras can
pick up fainter haloes and arcs than can
be seen with the naked eye. There may
be more faint detail hidden in your images
too, which the colour subtraction method
we look at here can reveal.
Colour subtraction is a process that
subtracts one colour channel from
another to help remove cloud structures
and dramatically enhance the edges of
the haloes, making them stand out better
against the background. It works more
HIƅFLHQWO\RQQRQFRPSUHVVHGUDZƅOHV
and subtracting the red from the blue
gives the best results.
The easiest way to do the colour
subtraction process is to use the channel
mixer in Photoshop. Here we go through
the steps we used to process our starting
LPDJH ULJKWWRS WRUHYHDODZHOOGHƅQHG
upper tangent arc, faint parry arc, parhelia
(sundogs) and a faint circumzenithal
arc. In this example, we used Photoshop

78 BBC Sky at Night Magazine March 2024

BEFORE
Circumzenithal arc

Parry arc

Upper tangent arc

Parhelion

Parhelion

AFTER

Circumzenithal arc

46° halo
Parry arc

22 ° halo

Left-side
parhelion

Upper tangent arc
Faint middle
Lowitz arc

Right-side
parhelion

S Top: Mary’s original colour image, taken from Oxfordshire, UK in May 2023 with a

Canon 1100D and 10–18mm lens at an exposure of 1/50” at ISO 100 f/22. Bottom: The final
colour-subtracted image revealing faint, hidden details of arcs, haloes and sundogs

3 QUICK TIPS

1. The output should be
greyscale, so make sure you tick
the ‘Monochrome’ box in the
channel mixer window.
2. White halos may require
different settings to bring them
out, so experiment with the colour
channel sliders.

S Screenshot 1: To begin, open or drag-and-drop your image file into Photoshop. From
the top menu, select Image > Adjustments > Channel Mixer

S Screenshot 2: In Channel Mixer, subtract the red channel, raise the blue channel and
make the image greyscale. Next, adjust to remove clouds and boost any haloes and arcs

S Screenshot 3: Our final settings were red –92%, green +12%, blue +124%, Constant +10%.
Once you’re happy with your adjustments, click ‘OK’ and then save your file

CS2, but the same steps can be followed
using newer versions. Older versions of
3KRWRVKRSFDQQRWRSHQUDZƅOHVEXW
you can use free software like FastStone
Image Viewer to save the raw image
DVDQXQFRPSUHVVHG7,))ƅOHZKLFKLV
3KRWRVKRSFRPSDWLEOH
Opening Photoshop, we dragged and
dropped in our image. From the top
menu, we clicked Image > Adjustments >
Channel Mixer (see Screenshot 1). In the
Channel Mixer box, we set the red channel
to –100%, the blue channel to +100% and

ticked the ‘Monochrome’ box to make the
image greyscale.

Cloud removal
Next, we adjusted each of the colour
channel sliders further until we removed
the cloud structures and got the best
GHƅQLWLRQSRVVLEOHRQWKHKDORHVDQG
arcs (see Screenshot 2). Note that aircraft
contrails will remain visible. We used
the ‘Constant’ slider to increase overall
brightness as much as needed. Some
faint, colourless haloes may need a

3. To get better results with JPEG
images, try subtracting the red
channel from the green channel.

different set of adjustments than coloured
ones, so this step will be particular to the
display you’ve captured and to the sky
conditions. With our image we ended
up with the red channel at –92%, green
channel at +12%, blue channel at +124%
and ‘Constant’ at +10% (see Screenshot
3). We clicked ‘OK’ to apply the changes,
then saved our image. If necessary, you
can make adjustments to the contrast
XVLQJ\RXUXVXDOLPDJHHGLWLQJVRIWZDUH
at this stage.
-3(*LPDJHVKDYHDYHU\SRRUTXDOLW\
blue channel due to compression, so if
that’s what you’re working with you may
get better results by following the above
steps but subtracting the red channel
from the green rather than from the blue.
Although some haloes and arcs are
rare, many are not. In fact, some optical
HIIHFWVRFFXUVLJQLƅFDQWO\PRUHIUHTXHQWO\
than rainbows, so while from any given
location you may see approximately
10–15 rainbows a year, avid observers can
spot upwards of 10 times that number of
optical phenomena.
The most commonly observed include
the 22° halo, parhelia (sundogs) or
paraselenae (moondogs), tangent arcs
and circumzenithal arcs. Some of those
ZHUHYLVLEOHLQRXUƅUVWLPDJHEXWWKHƅQDO
FRORXUVXEWUDFWHGLPDJHVKRZVWKHPRUH
rarely seen parry arc, 46° halo and middle
Lowitz arcs. It’s always worth doing the
colour subtraction on all photos of haloes,
because you never know what may be
hiding in them.

Mary McIntyre is
an outreach
astronomer and
teacher of
astrophotography

March 2024 BBC Sky at Night Magazine 79

Your best photos submitted to the magazine this month

ASTROPHOTOGRAPHY

FREE

BONUS
CONTENT
Find our extended
Gallery at
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U Milky Way over Volcán de Fuego
Chirag Upreti, Acatenango summit, Guatemala, 9 November 2023
Chirag says: “To get this shot
of Volcán de Fuego with the
Milky Way, I climbed to the
summit of Volcán de
Acatenango, another dormant
volcano. From 13,000ft, I had a clear view
and waited hours for it to erupt, with
Sagittarius on the right of the frame along
with the late-autumn Milky Way.”

80 BBC Sky at Night Magazine March 2024

Equipment: Sony a7 III camera, Sigma
14–24mm f/2.8 lens, Leofoto LS-255CEX
Ranger tripod
Exposure: ISO 2000 f/2.8, 20”
Software: Lightroom, Photoshop
Chirag’s top tips: “In night landscape
SKRWRJUDSK\SURƅFLHQF\ZLWK\RXU
equipment in the dark is paramount.

PHOTO
OF THE
MONTH
2XWLQWKHƅHOGSDWLHQFHDQGSHUVLVWHQFH
are also vital: sometimes, capturing your
envisioned shot demands waiting for the
ideal conditions, and repeated attempts.
So persist and keep shooting! Nightscapes
are an art–science blend, involving much
trial and error. Cherish both the process and
the best available outcomes as you explore
the night’s beauty.”

U The Andromeda Galaxy
Oliver Carter, Leesburg, Virginia, USA, 1–21 September 2023
Oliver says: “Capturing an Andromeda image worthy
of a large-format print has long been one of my
astrophotography goals, and this is now proudly
GLVSOD\HGLQP\KRPH,XVHGDQ+DOSKDƅOWHUWRUHDOO\
make the nebulae in the bands pop.”
Equipment: ZWO ASI6200MM camera, William Optics FLT 120
refractor, Sky-Watcher CQ350 Pro mount
Exposure: R 350x 180”, G 350x 180”, B 340x 180”, Ha 132x 600”, total 74h
Software: PixInsight, Photoshop

U Planetary nebula NGC 6826
Andrea Arbizzi, Modena, Italy, May 2023
Andrea says: ş1*&ZDVP\ƅUVWSODQHWDU\
nebula shot with my new 8-inch EdgeHD scope, after
upgrading from a 140mm refractor. For me it was
exciting because it was the start of a new adventure,
imaging such tiny deep-space objects.”
Equipment: ZWO ASI533MC Pro camera, Celestron EdgeHD 8-inch
Schmidt-Cassegrain, iOptron GEM45 mount Exposure: 14h 40’
Software: Astro Pixel Processor, PixInsight, Photoshop

Y Supernova remnant Sh2-224
and emission nebula Sh2-223
Bill Batchelor, Coquitlam, BC, Canada, October–December 2023
Bill says: “I enjoy taking images that contain multiple
deep-sky objects. These two are quite faint and
required a lot of integration time, but I was lucky to get
several clear nights.”
Equipment: ZWO ASI2600MM Pro camera, William
Optics FLT 98 refractor, Celestron AVX mount (DSO detail); ZWO
$6,003URFDPHUD&DQRQ()PP860OHQV ZLGHUƅHOG 
Exposure: 80h Software: PixInsight, Photoshop, NINA

March 2024 BBC Sky at Night Magazine 81

U Quadrantid meteor shower
Josh Dury, Glastonbury Tor, Somerset, 4 January 2024
Josh says: “I climbed the Tor in a bid to
capture the Quadrantids ‘raining down’ on
St Michael’s Tower. There was a lot of wind
and rain, but I captured this shot during 30
minutes of clear skies at around 3am.”
Equipment: Sony a7S II camera, Sigma 14mm f/1.4 DG
DN Art lens, Benro CyanBird tripod Exposure: ISO 1600
f/1.4, 10” Software: Photoshop, Lightroom

U Lobster Claw & Bubble Nebulae
Nicole Poersch, Prestwick, South Ayrshire,
September–November 2023
Nicole says: “Living on Scotland’s west
coast, it’s not easy to collect good data
due to our very changeable weather. This
LVWKHƅUVWWLPH,ŝYHPDQDJHGWRFROOHFW
over 20 hours of usable data.”
Equipment: ZWO ASI1600MM camera, William Optics
Zenithstar 73 refractor, iOptron CEM25P mount
Exposure: R 34x 60”, G 46x 60”, B 30x 60”, Ha 46x 600”,
OIII 38x 600”, SII 37x 600”, total 22h Software: PixInsight

82 BBC Sky at Night Magazine March 2024

U The Sun
Arturo Buenrostro, Dallas, Texas, USA, 24 November 2023
Arturo says: “I’m passionate about imaging the Sun because it
always looks totally different. Every time you look through the
WHOHVFRSHWKHUHŝVDOZD\VDQHZƆDUHEODFNVSRWVƅODPHQWVť
always a different landscape.”
Equipment: Player One Apollo M-MAX solar camera, Lunt
LS100MT solar telescope, Sky-Watcher EQ6-R mount Exposure: 50” video, best
of 2,500 frames Software: AutoStakkert!, RegiStax, Photoshop

Y The Moon
6WHYH:KLWƅHOG5HGUXWK&RUQZDOO'HFHPEHU
Steve says: “The Moon is an ideal learning object to practise on
using inexpensive equipment. I clamped the phone to my Maksutov
using a digiscoping adaptor and used the 10-second timer to avoid
camera shake.”
Equipment: Samsung A22 smartphone, Meade DS-2102 Maksutov
Exposure: ISO 10 f/1.8, 1/33”

V Galaxy cluster HCG 88
:DUUHQ.HOOHUDQG0LNH6HOE\UHPRWHO\YLD6&2EVHUYDWRU\
(O6DXFH2EVHUYDWRU\&KLOH$XJXVW
Warren says: “This Hickson Compact Group was expertly captured
by Mike using the PlaneWave CDK1000 and CDK700. For such
‘small’ galaxies, the resolution was excellent and AI-based tools
helped bring out the tiny details in each member of the group.”
Equipment: FLI ProLine PL16803 camera, PlaneWave CDK700
Ritchey-Chrétien (RGB), PlaneWave CDK1000 Ritchey-Chrétien (L)
Exposure: R 21x 900”, G 19x 900”, B 21x 900”, L 48x 900” Software: PixInsight

U The Pleiades
6WHYH$OOHQ&DOQH:LOWVKLUH1RYHPEHU
Steve says: “I love using a mono camera,
because you can check the quality and
content of each shot produced by
HDFKƅOWHULQUHDOWLPH0LVDIDYRXULWH
target as the blue nebulosity can be
a challenge. I was pleased with this result considering
we had an almost full Moon.”
Equipment: ZWO ASI1600MM camera, William Optics
FLT 132 refractor, Sky-Watcher EQ8-R mount
Exposure: R 10x 120”, G 10x 120”, B 10x 120”, L 10x 120”
Software: Astro Pixel Processor, Photoshop

ENTER YOUR IMAGE
Whether you’re a seasoned astrophotographer or a beginner just starting out, we’d love to see your images.
Send them to us at www.skyatnightmagazine.com/send-us-your-astrophotos

March 2024 BBC Sky at Night Magazine 83

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SEE PAGE 24

Find out more about how we test equipment at
www.skyatnightmagazine.com/scoring-categories

86

Should you splash out
on RVO’s Horizon 80 ED
IXOOLPDJLQJSDFNDJH"
Read our verdict

@THESHED/PHOTOSTUDIO

HOW WE RATE
(DFKSURGXFWZHUHYLHZLVUDWHGIRUSHUIRUPDQFHLQƅYHFDWHJRULHV
+HUHŝVZKDWWKHUDWLQJVPHDQ

PLUS: books on humanity’s lunar love
affair, the exploitation of space and more,
plus the latest astro gadgets and gifts

+++++ Outstanding +++++Very good
+++++Good +++++Average +++++Poor/avoid
March 2024 BBC Sky at Night Magazine 85

Our experts review the latest kit

FIRST LIGHT
RVO Horizon
80 ED refractor (full imaging package)
A solid, sensible choice if you’re stepping up to deep-sky imaging
WORDS: CHARLOTTE DANIELS

ALL PHOTOS: @THESHED/PHOTOSTUDIO

VITAL STATS
• Price £1,015
with 1.0x
flattener;
£1,025 with
0.8x flattener
• Optics FPL-53
doublet
• Aperture
80mm
• Focal length
560mm, f/7
• Focuser
Dual-speed
rack and pinion
• Extras Tube
rings, Vixen
bar, dovetail,
guidescope,
1.0x field
flattener,
illuminated
eyepiece
• Weight 3.45kg
(OTA), 4.75kg
(full package)
• Supplier Rother
Valley Optics
• Tel 01909
774521
• www.
rothervalley
optics.co.uk

R

efractors are generally considered an
ideal imaging telescope due to their
sturdiness and reliability. This makes
them attractive for beginners and
advanced astrophotographers alike.
The RVO Horizon 80 ED doublet joins Rother Valley
Optics’s Horizon family of imaging refractors, which
also includes the 60 ED, 72 ED and 102ED, each
instantly recognisable by their distinct orange and
turquoise tube rings and accents. We were keen to
see how this midweight sibling stacked up against
other doublets on the market.
We received the full Horizon imaging package,
which included an impressive array of imaging
accessories within a smart aluminium carry case.
1HVWOHGEHVLGHWKH27$ZKLFKFRPHVƅWWHGZLWK
tube rings, mounting points and a dovetail, were the
guidescope, an illuminated eyepiece and a 1.0x
ƆDWWHQHU<RXFDQLQVWHDGFKRRVHD[ƆDWWHQHU

86 BBC Sky at Night Magazine March 2024

when ordering from the RVO website. Overall, the kit
SURYLGHGDQH[FHOOHQWƅUVWLPSUHVVLRQZLWKDOO
components beautifully machined with a smart,
EUXVKHGPHWDOƅQLVK

Time to test it
Winter skies were typically temperamental, but we
soon had an opportunity to use the 80 ED for a visual
VHVVLRQSRSSLQJWKHH\HSLHFHLQWRWKHƅQGHUVFRSH
and attaching to the OTA (we should note that the
top Vixen bar arrived upside down, so an Allen key was
QHHGHGWRƆLSWKLVDURXQG :HSDUWLFXODUO\OLNHGWKH
DGMXVWDEOH9L[HQFODPSDWWDFKHGWRWKHƅQGHUVFRSH
ZKLFKPDNHVLWHDV\WRƅWDUDQJHRIGLIIHUHQW
mounting points, while the illuminated eyepiece
allowed us to swiftly locate and centre targets.
First slewing to a 60%-lit waxing Moon, we were
pleased with the 80 ED’s colour correction, observing
very little fringing, even when pushed to higher X

Illuminated crosshair
eyepiece
The 24mm eyepiece is a handy tool for many
astrophotography processes, including
ƅQHWXQLQJRXU*R7RPRXQWVWKURXJK
three-star alignment. Slotting easily into
the back of either the guidescope or
OTA, the red crosshairs also
allowed us to optimise
long-exposure images
via more accurate drift
alignment or centring
on guide stars.

SCALE

50mm guidescope with
helical focuser
Guiding is considered a must for maximum
exposure times. This 50mm Horizon guidescope
is perfect for imagers looking to make this leap.
,WDOVRGRXEOHVXSDVDQH[FHOOHQWƅQGHUVFRSHWR
help with manual star alignment. Meanwhile, the
helical focuser ensures no focus creep once a
guide camera is attached.

Top mounting points
$WRS9L[HQEDUDQGƅQGHUVFRSHPRXQW
are supplied, allowing for the addition of
a guidescope, guide camera or even a
second imaging telescope if desired. The
ability to easily adapt or upgrade is a
much-desired capability of any setup. As
accessories change, mounting options
can prove expensive, but the Horizon
80 ED solves many tinkering challenges.

March 2024 BBC Sky at Night Magazine 87

FIRST LIGHT
One to grab and go
At 80mm of aperture, the RVO Horizon 80 ED doublet is placed comfortably
between widefield and heavy-duty refractors, with a focal length that’s
perfect for Messier Catalogue and NGC objects, including nebulae, star
clusters, or galaxies such as Andromeda, M31. For astrophotographers who
are hungry for more imaging opportunities, it also provides an excellent
field of view for capturing the disc of the Moon.
But a refractor is only as good as its optics. The FPL-53 glass of the
Horizon 80 ED’s objective lens reduces aberrations to optimise image
quality. As a doublet, the two-lens system is also designed to limit light
distortions for a clean image, without the weight of extra glass. The
standard 30cm Vixen-style dovetail bar provides plenty of scope to
balance this OTA once kitted out with a full suite of accessories. This
makes it an ideal grab-and-go astrophotography option for a variety
of different mounts and configurations.

1.0x field flattener
$ƆDWƅHOGLVDQDVWURSKRWRJUDSK\HVVHQWLDOEXWRIWHQFDQŝWEH
GHOLYHUHGE\EHJLQQHUVHWXSV+RZHYHUWKHƆDWWHQHULQFOXGHGLQ
WKH+RUL]RQLPDJLQJEXQGOHDOORZHGXVWRFRUUHFWƅHOGFXUYDWXUH
'HVLJQHGIRUWKH+RUL]RQ('WKH[ƆDWWHQHUSUHVHUYHVLWV
PPIRFDOOHQJWKIRUSLQVKDUSVWDUV$QRSWLRQDO[
UHGXFHUƆDWWHQHULVDOVRDYDLODEOH

Rack and
pinion focuser
Furnished with a 10:1 microfocus, this dual-speed
focuser speeds up achieving sharp stars. A lock
secures focus once reached, while the indexed
GUDZWXEHIXUWKHUVLPSOLƅHVDVHVVLRQE\DOORZLQJ
\RXWRQRWHWKHIRFXVSRVLWLRQ7KHLQFKEDUUHO
is ideal for most imaging setups, although a
LQFKDGDSWRULVLQFOXGHG

88 BBC Sky at Night Magazine March 2024

Crisp stars in the California
Nebula, using a Starlight Xpress
+ZLWK$VWURGRQQPƅOWHUV
X

Focus holds perfectly
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SRSXODUZLQWHUWDUJHWVWKH+HDUW1HEXODDQGWKH
&DOLIRUQLD1HEXOD:HZHUHSDUWLFXODUO\LPSUHVVHG
ZLWKWKH('ŝVIRFXVHUZKLFKSURYLGHGMXVWWKHULJKW
DPRXQWRIWHQVLRQDVZHSHUIHFWHGRXUVWDUVXVLQJ
WKHƅQHIRFXV:KLOHWKHIRFXVORFNZDVDOLWWOH
GLIƅFXOWWRUHDFKZLWKJORYHGKDQGVLQWKHGDUNWKH
UHVWRIWKHDGMXVWPHQWNQREVZHUHODUJHDQGHDV\WR
JULSPDNLQJƅQHWXQLQJWKLVUHIUDFWRUDEUHH]H
6WDFNLQJDQGSURFHVVLQJHDFKLPDJHVKRZHGWKDW
WKHƆDWWHQHUKDGDFKLHYHGDƆDWƅHOGRIYLHZDQG
FULVSWDUJHWVWKDWZHUHHDV\WRƅQHVVHLQ3KRWRVKRS
&RQVLGHULQJWKHSULFHSRLQWWKHIXOOLPDJLQJ
SDFNDJHLVDQLGHDOSURVSHFWIRULPDJHUVDOUHDG\
IDPLOLDUZLWKDVWURSKRWRJUDSK\ZKRNQRZWKDWWKH\ŝOO
XVHLW7KDWLVQRWWRVD\KRZHYHUWKDWWKH('LVQŝW
DSSURSULDWHIRUEHJLQQHUVLWFHUWDLQO\LVVLPSOHWR
RSHUDWH7KHDFFHVVRULHVSURYLGHGLQWKH+RUL]RQ

Fine-tuning was a breeze to
create this detailed Heart
Nebula in 25x 300” Ha and
22x 300” OIII exposures

LPDJLQJSDFNDJHJLYHUHODWLYHQHZFRPHUVDQ
LPSRUWDQWDGYDQWDJHWKHFDSDFLW\WRSURJUHVV
DQGDGDSWDVWDUJHWOLVWVGHYHORSRUXVHUVVHHN
WRPD[LPLVHWKHLUGDWDFDSWXUHFDSDELOLWLHV
:HIHOWWKDWWKLVZDVDQLGHDOEXQGOHIRU
DVWURSKRWRJUDSKHUVORRNLQJWRJUDGXDWHIURP
ZLGHƅHOGWRGHHSVN\LPDJLQJRUVXSSRUWWKH
WUDQVLWLRQIURPPDQXDOO\RSHUDWLQJD*R7RPRXQW
WRDJXLGHGRUODSWRSGULYHQVHWXS)RUXVLWFHUWDLQO\
URVHWRWKHFKDOOHQJH7KH+RUL]RQ('LVDVWXUG\
LPDJLQJZRUNKRUVHWKDWZLOOKROGLWVRZQIRUPDQ\
\HDUVRIGHHSVN\FDSWXUH

VERDICT
Build & design
Ease of use
Features
Imaging quality
Optics
OVERALL

+++++
+++++
+++++
+++++
+++++
+++++

KIT TO ADD
1. =:2PLQL
ƅOWHUZKHHO
2 2SWRORQJ
/3UREURDGEDQG
OLJKWSROOXWLRQ
LQFKƅOWHU
3 2SWRORQJ
/H1KDQFHGXDO
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GHHSVN\
LPDJLQJ
LQFKƅOWHU

March 2024 BBC Sky at Night Magazine 89

@THESHED/PHOTOSTUDIO X 4, CHARLOTTE DANIELS X 2

PDJQLƅFDWLRQV8VLQJRXUPPH\HSLHFHDW[
PDJQLƅFDWLRQZHHQMR\HGVRPHEHDXWLIXOO\FULVS
FUDWHUGHWDLOV0RYLQJDFURVVWRWKH3OHLDGHVZHZHUH
WUHDWHGWRDFOHDUDQGVKDUSYLHZ
%HIRUHWKHFORXGVUROOHGLQZHDWWDFKHGRXU'6/5
DQGƅUHGDFRXSOHRIWHVWVKRWVPLQXVWKHƆDWWHQHU
:KLOHWKHUHZDVDVPDOODPRXQWRIFXUYDWXUHWRZDUGV
WKHHGJHVRIWKHƅHOGWKLVZDVE\QRPHDQV
SURKLELWLYHRUEH\RQGVRPHSRVWSURFHVVLQJWULFNV
/DWHUZHVHWWKH('XSIRURXUQH[WLPDJLQJ
ZLQGRZ%RWKƆDWWHQHUVUHTXLUHPPEHWZHHQWKHP
DQGWKHFDPHUDVHQVRUDQGZKLOHWKLVLVWKHLQGXVWU\
VWDQGDUGZHŝGDOZD\VUHFRPPHQGVHSDUDWHO\
SXUFKDVLQJDJRRGVHOHFWLRQRIVKLPVDQGVSDFHUVWR
HQVXUHWKLVFDQEHUHDFKHGIRU\RXUFDPHUD)RURXU
PRQRFKURPH&&'DQGƅOWHUZKHHOZHZHUHHDVLO\VHW
XSZLWKWKHKHOSRIDVSDFHU:HVKRXOGKLJKOLJKWWKDW
ERWKƆDWWHQHUVSURYHGYHU\WLJKWWRVFUHZRQOHDYLQJ
XVLQQRGRXEWWKDWWKH\ZHUHVHFXUHRQFHƅWWHG

Our experts review the latest kit

FIRST LIGHT
QHYCCD

QHY5III200M mono camera
This fast planetary camera has bonus turbulence-busting near-infrared capability
WORDS: TIM JARDINE

ALL PHOTOS: @THESHED/PHOTOSTUDIO

VITAL STATS
• Price £319
• Sensor SC2210
CMOS
• Sensor size
1,920 x 1,080
• Frame rate
Full resolution
96.5fps at 8 bit;
60fps at 16 bit
• Exposure range
15ms–15
minutes
• Memory 512MB
DDR3 RAM
• Connectivity
USB 3.2, ST4
• Size 77mm
x 40mm
• Weight 90g
• Extras
IR850nm filter,
storage tin,
USB cable, ST4
guiding cable,
spacer rings
• Supplier
Modern
Astronomy
• Tel 020 8763
9953
• www.modern
astronomy.com

Q

HYCCD cameras have a great
reputation, but the latest QHY5 version,
known as the QHY5III200M, features
VRPHXVHIXOUHƅQHPHQWV$GXDO
purpose, monochrome camera, it gives
KLJKSHUIRUPDQFHIRUSODQHWDU\LPDJHVDQGDFWVDV
DVHQVLWLYHDQGUHOLDEOHDXWRJXLGLQJFDPHUD
7KHFDPHUDLVVPDOODQGOLJKWZLWKDLQFK
EDUUHODQGIRXUURXQGƅQVWKDWVSOLWWKHFDPHUDLQWR
WZRVHFWLRQVWKHUHDUWKLUGRIWKHERG\KRXVLQJWKH
FRQQHFWLRQVZKLOHWKHIURQWWZRWKLUGVFDQEH
LQVHUWHGLQWRDLQFKH\HSLHFHKROGHU7KHƅQV
KHOSWRGLVVLSDWHDELWRILQWHUQDOKHDW7KHUHŝVD
4XLFN6WDUWFDUGLQWKHER[DOZD\VDZHOFRPHVLJKW
DQGIROORZLQJWKHƅYHVLPSOHVWHSVZHKDGWKH3')
PDQXDOGRZQORDGHGZLWKWKHFDPHUDVRIWZDUHLQMXVW
DIHZPLQXWHV4+<&&'KDVLWVRZQFDPHUDFRQWURO
DSSFDOOHG(=&DS47ZKLFKLWUHFRPPHQGVEXW

Rings and
accessories
A well-thought-out
selection of useful mount
DGDSWRUVVSDUHƅOWHU
holder, focus adjustment
ring and even a couple of
Delrin spacers are included.
These thin spacers are
great for preventing the
various adaptors from
getting stuck together.

90 BBC Sky at Night Magazine March 2024

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6KDUS&DSLQFOXGHGLQWKHVRIWZDUHDQGZHFKRVH
WKDWDVRXUFDSWXUHDSSOLFDWLRQ

Need for speed
)RUSODQHWDU\LPDJLQJVSHHGRIFDSWXUHLVWKHNH\WR
JHWWLQJJRRGUHVXOWV:KHQWKHVHHLQJLVSRRUEHLQJ
able to quickly capture a large number of frames
HQDEOHVXVWRVHOHFWRQO\WKHEHVWIURPWKHPL[:KHQ
the target is rotating relatively quickly too, as Jupiter
GRHVLWŝVDQDGYDQWDJHWREHDEOHWRJDWKHUWKHEHVW
GDWDLQWKHVKRUWHVWSRVVLEOHWLPH:LWKWKLV
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SCALE

IR850nm filter
The clear CMOS chip cover can be replaced with the
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This can allow for sharper lunar and planetary images
on nights with poor seeing, as infrared light is less
affected by atmospheric turbulence.

512MB DDR3 RAM
A hefty half-gigabyte of fast onboard memory enables the
QHY5III200M to charge through data capture as fast as it
can, buffering the data as the images are produced,
thereby reducing the pressure on the recording computer
to keep up with the high speed of the camera.

USB
connection
It’s nice to see the new
standard USB 3.2 Type-C
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camera, as this offers a
solid and dependable
connection that’s easier
to insert in the dark.
A good-quality 1.8-metre
QHYCCD-branded USB
cable is included in the
package.

March 2024 BBC Sky at Night Magazine 91

FIRST LIGHT
High near-infrared sensitivity
QHYCCD describes the SC2210
sensor as a ‘domestic CMOS’ unit.
It isn’t entirely obvious what they
mean by this, but that doesn’t
detract from the excellent
performance that the diminutive
chip is capable of. The 4+m x 4+m
pixels are arrayed in a 1,920 x
1,080 grid for this 2MP camera,
and exposure times between 15
milliseconds and 15 minutes are
possible. Being sensitive to
near-infrared wavelengths adds
an extra dimension to this
camera and opens up the
possibility of imaging in less-

than-ideal conditions using the
IR850nm filter. It could be a
useful camera for capturing
images of close double stars and
similar objects that need a bit of
manipulation to get around any
issues with seeing, and to that
end we used the high sensitivity
to the red end of the spectrum to
get a close-up image of Orion’s
delightful Trapezium region,
which is rich in bright hydrogen
and sulphur emissions. This
‘domestic’ CMOS chip is capable
of revealing the secrets of
deep-sky objects too.

Handy tin

@THESHED/PHOTOSTUDIO X 3, TIM JARDINE X 5

The camera is supplied in a handy storage tin that is foam-lined,
with cut-outs to protect the unit in storage. There’s room for the
camera, a USB cable and the various other accessories, including
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92 BBC Sky at Night Magazine March 2024

S The infrared filter allows sharp lunar

S Jupiter, shot through thin cloud in RGB,

images like this Lunar X clair-obscur shot

2,000 frames each, best 30 per cent stacked

S A highlight of our testing session was
capturing Uranus and five of its moons

Sunspots captured
with the addition of
a white-light filter

X

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VERDICT
Build & design
Connectivity
Ease of use
Features
Imaging quality
OVERALL

+++++
+++++
+++++
+++++
+++++
+++++

S Making the most

of the camera’s
near-infrared
sensitivity for a
close-up of Orion’s
Trapezium Cluster

KIT TO ADD
1. QHYCCD
QHYCFW3-SSR 7x 1.25-inch/
PPƅOWHU
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2 $VWURQRPLN
/5*%7\SHF
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3 QHYCCD mini
JXLGHVFRSHNLW

March 2024 BBC Sky at Night Magazine 93

Charlotte Daniels rounds up the latest astronomical accessories

GEAR
1 Ouranos Pro: Weather Astronomy app

2
1

Price from £2.99 • Supplier Starmaze
www.ouranos-app.com
Available for Apple and Android devices, this app
offers hour-by-hour forecasts for astronomers,
including the seeing, cloud cover and visibility from
your location. The Pro version provides a seven-day
forecast, updated hourly.

2 3 Legged Thing Charles 2.0 tripod
Price £319.99 • Supplier 3 Legged Thing
www.3leggedthing.com
$VWXUG\WULSRGLVNH\IRUFDSWXULQJZLGHƅHOGLPDJHV
and this magnesium alloy version is both lightweight
and stable. The full kit, including carry bag and AirHed
Pro ball head, weighs in at 2.44kg with a 40kg load
capacity, allowing easy carriage to dark-sky sites.

3 Jodrell Bank coasters
Price £14 • Supplier Kitsch Republic
www.kitschrepublic.co.uk
Astronomy accessories don’t need to stay outdoors!
This set of four colourful coasters featuring Jodrell
Bank’s famous Lovell Telescope will liven up any room.
Made from hardboard, they are heat, water and fade
resistant. Jodrell-themed cushions are also available.

3

4 Celestron lens pen

4
5

6

Price £12 • Supplier Harrison Telescopes
www.harrisontelescopes.co.uk
Dust on your lenses calls for specialist equipment to
avoid damaging the delicate glass. This small and
lightweight pen is easy and safe to use, perfect for
on-the-go optics maintenance.

5 Chroma 3nm Ha high speed ultra
narrowband filter
Price from £575 • Supplier First Light Optics
www.ƅUVWOLJKWRSWLFVFRP
Capturing hydrogen-alpha is key for detailed images
RIQHEXODH7KLVXOWUDQDUURZQPƅOWHULVGHVLJQHGIRU
fast imaging telescopes with a focal ratio of f/3 and
ensures optimal separation from sulphur emissions.
Available in 1.25-inch and 2-inch versions.

6 Astronomy neck gaiter
Price £24.99 • Supplier Astro Gear
www.astrogear.co.uk
Spring nights in the UK still mean cold dark skies,
which can affect our stamina for long observing
sessions. This fun, galaxy-themed neck gaiter will help
you stay toasty but stylish, and it can turn into a
handy bandana for the summer months.

March 2024 BBC Sky at Night Magazine 95

New astronomy and space titles reviewed

BOOKS
humans and our planet. From the opening
pages of the introduction, the reader is
drawn into the story by a factual account
of war and the importance of the Moon’s
WLGDOLQƆXHQFH
Boyle takes us back billions of years to
explain the birth of the Moon, before
going on to explore the effects that our
closest companion has on our natural
world, with some enjoyable and
interesting details about ‘calendar
keeping’ organisms. She introduces us to
the ancient astronomers and pioneers of
WKHVFLHQWLƅFUHYROXWLRQZKRFKDQJHGRXU
understanding of the Solar System, and
the astronauts who bravely stepped on
the Moon’s surface, topics that Boyle
presents easily and concisely.
Throughout the book, she writes about
the lunar journeys she has personally
made and the people she has met while
undertaking her study of the Moon, from
Rebecca Boyle
archaeoastronomers to scientists at
Sceptre Books
NASA. The record of the author’s own
£22 z HB
journey is an entertaining addition to the
Why are we so fascinated with the Moon?
book. There are no illustrations, which is a
It is a cold wasteland, devoid of life,
shame for newcomers to the subject who
but since our ancient ancestors
PD\KDYHEHQHƅWWHGIURP
walked the Earth, the Moon
diagrams and images to
has been a source of
aid their understanding.
wonder and curiosity,
That aside, Our Moon
evoking spiritual
is a splendid,
feelings within us
thought-provoking
and featuring
tale of the ‘eighth
heavily in art,
continent’, the
literature and
author inviting us
song. Formed
to consider the
4.5 billion years
Moon in the past
ago, our lifeless
and present, and to
Moon has played
ponder what the
an important part
future may hold.
in evolution on Earth:
One thing is clear: even
it stabilised our orbit
in this modern age of
Special relationship: Boyle’s
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discovery and
globe-trotting tale captures why
climate, natural world
understanding, our
our Moon is so special
and tides.
fascination with the
Our Moon: A Human History, written
Moon, and the prospects it may hold,
by award-winning science writer and
certainly hasn’t waned. ★★★★★
journalist Rebecca Boyle, is an insightful
Katrin Raynor is an astronomy
and captivating read about the historical,
writer and a fellow of the Royal
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Astronomical Society
has had, and continues to have, upon

STEVE MARSH

Our Moon:
A Human History

96 BBC Sky at Night Magazine March 2024

Interview with
the author
Rebecca Boyle
How important
is the Moon?
You can’t
overstate its
importance.
Thanks to its
cycles, we invented
timekeeping, civilisation, religion,
philosophy, the scientific method,
even science fiction. The Moon’s tide
dragged vertebrates onto shore,
enabling the evolution of life on land.
The Moon stabilised the climate of
our planet over millennia. It’s
beautiful: a muse for poetry and art,
a companion in the night.
What’s your favourite lunar feature?
I love Mare Imbrium, the ‘Sea of
Rains’. It makes me think of
springtime, the promise of growth.
It’s one of the largest impact basins in
the Solar System: something huge
must have walloped the Moon to
carve it out, enabling it to fill with
soft magma later. The Apollo
missions landed in roughly the same
area, and there’s a chance most of the
samples are Imbrium rocks, making
it harder to draw conclusions about
the overall Moon.
How do you feel about future
lunar missions?
We risk marring the Moon’s
unspoiled beauty. We tend, as a
species, to act rapaciously in our
expansions. On the Moon, there are
no peoples at risk of exploitation, but
Moon exploration efforts are imbued
with some of the language and
motivations that caused past tragedy
on Earth. Mining rigs, settlements,
even corporate logos may be visible
on the Moon in the near future. We
need to be cautious and consider the
Moon’s role in our shared history,
before we turn it into a mining depot,
or worse, a battlefield.

Rebecca Boyle is a science writer
and lifelong Moon enthusiast

Eyes in the Sky

Choosing &
Using Binoculars

Andrew May, edited by Brian Clegg
Icon Books
£10.99 z PB
Eyes in the Sky:
Space Telescopes
from Hubble to
Webb isn’t really a
just title for this cute
little book. Yes, it’s
all about space
telescopes, but over
six chapters the
author covers most
of the electromagnetic spectrum, not just
the regions that Hubble and Webb span.
In 150 pages, the reader is taken on a
voyage through successive generations of
telescopes designed to study everything
from the cosmic microwave background,
which includes COBE, WMAP and Planck,
to the planet hunters TESS and Kepler.
Given the compact nature of Eyes in
the Sky, it’s a quick read and clearly
designed to prompt the reader to further
investigation. The book explores the
tremendous science contributions of

Astrotopia
Mary-Jane Rubenstein
University of Chicago Press
£15 z PB

15 telescopes, starting with perhaps the
most famous of them all: the Hubble
Space Telescope. As the story evolves,
May touches on the most exciting
discoveries in astrophysics and cosmology
in the last few decades, covering the life
cycle of stars, the structure of galaxies
and the evolution of the Universe.
The author nicely describes the
instruments that feature on each
telescope, their purpose and the reasons
behind the odd naming conventions. In
places some of the descriptions of key
ideas are too brief, and the final chapter
on future telescopes does not do justice
to the excitement of planned missions
over the next decade. However, the
writing is accessible and engaging, and
will no doubt spark the imagination of
any space enthusiast. ★★★★★

Laura Nuttall is a Future Leaders
fellow at the University of Portsmouth

SPACE
RACE

Elon Musk does not
come out well in this
book. Nor does Jeff
Bezos. These facts
alone make for a
compelling read, but
they only constitute
Rubenstein’s
opening gambit.
Her target is far
broader, as she tells an at first depressing
story of how the giant, international
corporations that now dominate and
control life on Earth are trying to do the
same with space.
The first half of the book makes for
alarming reading. For many of us,
astronomy is about a sense of wonder,
curiosity and awe, about learning and
understanding. This is not, as Rubenstein
argues, the view of the corporations now
taking over space exploration from
governments. Instead, they consider
space exploration in the same way that

European colonists saw terrestrial
exploration: as a source of resources to
make the rich richer. The second half of
the book thankfully gives a more uplifting
message, one of hope and of new ways to
view both our Earth environment and that
of space.
Astrotopia keenly analyses current
trends in space exploration in a way that
feels fresh and original. While Rubenstein
acknowledges arguments that ask why
billionaires are spending so much on
space exploration when they could solve
world hunger and/or climate change, she
does not conclude that space should not
be explored. Rather, the argument is that
we explore space with care and respect.
This is an excellent book that makes so
much sense of the recent history of space
exploration, while leaving a strong sense
of hope for the future. ★★★★★

Emily Winterburn is an astronomy
historian and author

Neil T English
Springer
£24.99 z PB
This comprehensive
‘Guide for Star
Gazers, Birders and
Outdoor Enthusiasts’
is unique in that it
describes, reviews
and compares more
than a hundred
different models
of binocular.
The book is organised in two parts.
The first, A Survey of the Binocular
Market, begins with a comprehensive
introduction to binocular basics and an
interesting history of binoculars, before
looking at what is available in various
classes of binocular, one of which is
astronomical. The second part includes
an overview of some better-known
binocular brands, some recommended
accessories and ‘top bargains’, as well as
information on testing binoculars. There
is a glossary and an index.
English’s familiarity with binocular
optics becomes evident in the opening
chapter, Binoculars 101, where he leads
the reader from the simple basics to the
optical qualities of different glass and
prism types. His love of binoculars shines
through his prose – and his poetry: he
has even included a paean to one of his
favourite pairs!
The writing style varies between very
formal (“this author”, “the reader”) to
conversational (“I hope you’ll agree”). The
reviews are mostly his own, but he has
included the opinions of people he knows
and information from other reviews.
There are a few production and
copy-editing issues. For example, the
glossary of binocular terminology is not
arranged alphabetically, and there are
inconsistent designations such as BK7,
BK-7, BAK7 for the same glass, but these
do not greatly detract from the overall
utility of the book.
If you want the most comprehensive
overview of binoculars in a single resource,
this book is for you. ★★★★★

Steve Tonkin is a binocular
astronomer and astronomy
communicator
March 2024 BBC Sky at Night Magazine 97

Anita Chandran interviews Dr Robert Shelton

Q&A WITH AN OBSERVATORY PRESIDENT
The world’s most powerful observatory – the Giant Magellan Telescope,
currently under construction in Chile – is set to be a science behemoth
ILLUSTRATION

What capabilities will the
Giant Magellan Telescope
offer astronomers?
The Giant Magellan Telescope
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After the molten glass has been cast, how long
does it take one of the primary mirrors to cool off?
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What are the advantages of ground-based
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98 BBC Sky at Night Magazine March 2024

S “It’s going to

unveil images, ideas
and data that we
can’t even imagine
yet”. The largest
optical telescope
the world has seen
is due online by 2031

Robert Shelton
is the president of
the Giant Magellan
Telescope
Observatory
(GMTO), responsible
for the construction
of the new
25.4-metre Giant
Magellan Telescope

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Will the Giant Magellan work in chorus with
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What inspires you about working with the Giant
Magellan Telescope?
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THE SOUTHERN HEMISPHERE
With Glenn Dawes

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of the Moon and the unassuming constellation Pictor

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15 Mar at 23:00 AEDT (12:00 UT) The sky is different at other times as the stars
31 Mar at 22:00 AEDT (11:00 UT) crossing it set four minutes earlier each night.

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RADIANT

VARIABLE STAR

QUASAR

MAG. +3

COMET TRACK

PLANET

MAG. +4
& FAINTER

BBC Sky at Night Magazine March 2024

MAG. 0
& BRIGHTER
MAG. +1
MAG. +2

NORMA

RPI

6

DOUBLE STAR

OPEN CLUSTER

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4th

Just 0.6° west of Eta2 lies double star
HD 32278, with mag. +7.3 and +9.0
yellow companions 10 arcseconds apart.
A true showpiece is Theta (e) Pictoris (RA
5h 24.8m, dec. -52° 19’). With matched mag.
+6.8 stars a comfortable 38 arcseconds
apart, Theta stands out in the field of view
like brilliant white headlights.

Chart key
CHART: PETE LAWRENCE

M5

showing an oval halo (1.0 x 0.5 arcminutes)
with a stellar nucleus.

M4
Antares

M19

This month, a trip to the Pictor
constellation, just west of Canopus,
home to impressive double stars such as
Eta (d Pictoris (RA 5h 02.8m, dec. -49° 09’).
Binoculars show a colourful wide pair,
with mag. +5.4 white Eta1 (d making a
great contrast to mag. +5.0 orange Eta2 (d
0.5° away. Here’s a real challenge requiring
dark skies and large aperture (20cm+): in
the same field with Eta2 (0.1° east) is the
faint (12th-magnitude) galaxy NGC 1803,

PLANETARY
NEBULA

APUT

DEEP–SKY OBJECTS

GLOBULAR
CLUSTER

_

Red Planet, as it drops into the dawn glow
heading towards conjunction. By month’s
end this ‘Morning Star’ is a dawn object
only. Saturn returns to the morning, rising
out of the Sun’s glow, and passes Venus,
being closest on 22nd, only 0.6° apart.

OPHIUCHUS

You need to start early to see planets
this month, for Jupiter and Uranus are
setting around 21:00 (mid-month). A
drought then sets in until Mars arrives in
the predawn. This is followed by brilliant
Venus, which quickly moves away from the

GALAXY

b

THE PLANETS

SERP
ENS C

Argo, the ship of Jason and the
Argonauts fame, and one of
Ptolemy’s original 48 constellations, today
exists as Vela, Puppis and Carina. They
retain many links to Argo, including Arabic
star names, but Gamma Velorum (in Vela)
is also known as ‘Regor’, which is Roger
backwards. Gus Grissom inserted this into
NASA’s star charts as a joke on his fellow
astronaut Roger Chaffee. When they were
ERWKNLOOHGLQWKH$SROORƅUHWKHQDPH
remained to honour their memory.

b

STARS AND CONSTELLATIONS

The Moon slowly wobbles on its axis,
allowing us to see slightly more than
half of its surface. However, those revealed
areas are often still in shadow. The two
maximum librations in March are both
visible. One occurs during the last quarter
Moon on 5 March, where the western limb
shows the dark crater Grimaldi more
face-on. The other, on 17 March, has the
first quarter Moon displaying great views
of Mare Crisium, with Mare Marginis now
peeking over the eastern limb.

E A ST

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BBC Sky at Night Magazine March 2024

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