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Welcome HOW TO CONTACT US Webb is here – and it’s  Subscriptions, binders and back issues a case of love at first sight 03330 162119* Mon–Fri 9am–5pm On 12 July the Sky at Night Magazine team waited with bated breath, excited to see the first images from the James Webb Space *Calls from landlines will cost up to 9p per minute. Call Telescope. And they did not disappoint. We were spellbound and charges from mobile phones will cost between 3p and amazed by the detail, depth and structure JWST captured. See for 55p per minute but are included in free call packages. yourself on page 6 in our special Eye on the Sky gallery, which we’ve If calling from overseas, please dial +44 (0)1604 973727 dedicated entirely to the infrared telescope’s first images. Editorial enquiries +44 (0)117 300 8754 And then came the science. We sat wide-eyed as Webb’s ability to 9:30am–5:30pm, Mon–Fri break down light into its component parts through spectroscopy Advertising enquiries +44 (0)117 300 8803 was revealed, dazzled that we were being shown individual elements in dust clouds circling the event horizon of a supermassive black hole  Print subscription enquiries 310 million lightyears away. Yet this is just one part of JWST’s www.buysubscriptions.com/contactus science programme; turn to Colin Stuart’s feature on page 28 to Digital subscription enquiries discover the other areas the telescope will impact. Also in this www.buysubscriptions.com/contactus special issue, on page 18 we hear from astrophysicist Mikako Editorial enquiries Matsuura about working with JWST, and The Sky at Night presenter [email protected] Chris Lintott gives his thoughts on Webb’s first images on page 11.  Subscription enquiries Back on Earth, it’s an exciting time to be observing the night sky. UK enquiries: FREEPOST OURMEDIA Jupiter is at opposition and at its brightest, a great time to follow (please write in capitals) Pete Lawrence’s guide to making an animation of it on page 66. The Overseas enquiries: PO Box 3320, King of Planets is joined by four of the Solar System’s other worlds all 3 Queensbridge, Northampton, NN4 7BF, UK this month, creating an enchanting line-up in evening skies. Turn to page 35 for Stuart Atkinson’s advice on seeing this planetary parade. Editorial enquiries BBC Sky at Night Magazine, Our Media Enjoy the issue! (an Immediate Group Company), Eagle House, Bristol, BS1 4ST Chris Bramley, Editor Become an Insider PS Our next issue goes on sale on Friday 16 September. The more we know about what you like, the better placed we are to bring you the best magazine possible. So we’d like to invite you to join our online reader panel ‘Insiders’. Just log on to www.immediateinsiders. com/register to fill out the short registration survey and we’ll be in touch from time to time to ask for your opinions on the magazine and other relevant issues. Sky at Night – lots of ways to enjoy the night sky… Television Online Social media Podcasts Tablet/phone eNewsletter Find out what The Visit our website Follow us on Twitter, Listen to our Radio Get each month’s The best targets to Sky at Night team for competitions, Facebook and Astronomy podcasts issue on your Apple observe each week, have been exploring astrophoto Instagram for space where the magazine or Android device, delivered to your in recent and past galleries, observing news, astro images team and guests now with bonus inbox. Visit bit.ly/ episodes on page 18 guides and more and website updates discuss astro news image galleries skynewsletter Find out more at: www.skyatnightmagazine.com September 2022 BBC Sky at Night Magazine 3

JAMES WEBB SPACE TELESCOPE SPECIAL SEE PAGES 6, 11, 18, 28 CONTENTS C =onthecover = JWST special Reviews 86 StellaLyra 8-inch Features Regulars 6 Eye on the sky C f/6 Dobsonian C 28 JWST begins its 11 Bulletin 90 Sky-Watcher Evolux science journey 16 Cutting edge 18 Inside The Sky at Night 62ED refractor C We look at the BIG questions 20 Interactive 94 Books the Webb Telescope will answer 23 What’s on 96 Gear 25 Field of view 35 Prepare for the planet parade 26 Subscribe to BBC Sky The Sky Guide C 16-PAGE 44 Highlights CENTRE C A string of worlds to spot at Night Magazine PULLOUT throughout September 72 Explainer C COVER IMAGE: XXXXXXXXX. THIS PAGE: NASA/ESA/CSA/STSCI, ARUIZHU/ISTOCK/ 74 DIY astronomy C 46 The big three GETTY IMAGES, @THESHED_PHOTOSTUDIO, NASA, PETE LAWRENCE, BBC 40 The periodic table of 98 Q&A: the CEO of Inmarsat Messier objects 48 The planets Astrophotography A new way to view Messier’s list 76 Capture 50 September’s all-sky chart 78 Processing 60 Glorious globulars 80 Gallery 52 Moonwatch C 15 gorgeous star clusters to find 53 Comets and asteroids in the sky this month 53 Star of the month 66 Animating Jupiter 54 Binocular tour C Turn your pics into mini-movies of the planet and its moons 55 The Sky Guide challenge 56 Deep-sky tour 58 September at a glance 4 BBC Sky at Night Magazine September 2022

New to astronomy? Extra content To get started, check out our guides and glossary at ONLINE www.skyatnightmagazine.com/astronomy-for-beginners Visit www.skyatnightmagazine. 35 com/bonus-content/VOCFQDB to access this month’s selection of exclusive Bonus Content SEPTEMBER HIGHLIGHTS Interview: the science behind JWST Instrument scientist Dr Pamela Klaassen reveals how the James Webb Space Telescope observes the Universe. 60 86 72 66 This month’s contributors Watch online: Download astronomy The Sky at Day observing forms Summer sees the nights Print out our report get shorter. In this special forms to help you keep episode, Maggie and track of all your Chris reveal what to see planetary and solar in the sky during the day. observing sessions. Paul Money Melissa Brobby Ezzy Pearson The Virtual Planetarium Reviews editor Amateur astronomer Features editor Pete Lawrence and Paul Abel guide us through the best sights to see in the night sky this month. “Globular “It was “Mae clusters fascinating Jemison September 2022 BBC Sky at Night Magazine 5 always to talk to really has remained Rajeev some drive. fuzzy blobs until I added about the changing From a little girl in more aperture to view views on space today, Detroit watching Star them, revealing their compared to how it Trek to the first Black distinct and individual was during the Apollo woman in space, to personalities in all their era.” Melissa finds out leading humanity’s way glory.” Paul introduces what the younger across the stars.” Ezzy 15 globulars you really generation think salutes multi-talented should meet, page 60 about space, page 98 Mae on page 72

NASA/ESA/CSA/STSCI 6 BBC Sky at Night Magazine September 2022

JAMES WEBB SPACE TELESCOPE SPECIAL JWST LIGHTS UP THE UNIVERSE In July, a momentous new era in space science began when NASA released the first full-colour images from the James Webb Space Telescope. We look at the first five that stunned the world Captured in infrared light, this image of radiation emitted by newborn stars located are views of these stellar nurseries and ‘Cosmic Cliffs’ within the Carina Nebula, just above the area shown in the image. pockets of young stars that until now were 7,600 lightyears away, reveals structures The ‘haze’ that seems to be rising from the beyond humanity’s reach. and star-forming regions previously wall is ionised gas and hot dust streaming unseen by human eyes. It’s a much-loved away from the nebula under relentless Commenting on Webb’s first images, target for amateur astronomers and radiation pressure. NASA deputy administrator Pam Melroy astrophotographers, but no one will ever said: “What I have seen moved me, have seen it like this. Webb’s NIRCam instrument, which was as a scientist, as an engineer and as a used to capture this image, observes in human being.” Having seen them now for This glowing ‘wall’ is the edge of a cavity infrared, enabling astronomers to peek ourselves, it’s difficult not to agree with her. within the nebula that features peaks through the dense cosmic dust and get a of cosmic gas and dust seven lightyears good look at what’s really going on at the TURN THE PAGE FOR MORE OF high. It’s being hollowed out by the intense heart of this nebula. What we are seeing WEBB’S BRAND NEW IMAGES September 2022 BBC Sky at Night Magazine 7

NASA/ESA/CSA/STSCI X 6  Field of dreams This is the deepest infrared image of the distant Universe ever captured. Webb’s First Deep Field is bursting with thousands of galaxies, but the focus is SMACS 0723, a galaxy cluster so far away it appears to us as it did 4.6 billion years ago. Its mass is so staggering that the light from background galaxies is magnified and contorted by gravitational lensing. This image alone is a treasure trove for scientists to unpack.  Two glorious rings Not one view of the Southern Ring Nebula, but two. This is a planetary nebula, a dying star shedding its layers into space, captured in both near-infrared (left), and mid- infrared (right) where we can actually see the remnant white dwarf core (the redder of the two). 8 BBC Sky at Night Magazine September 2022

JAMES WEBB SPACE TELESCOPE SPECIAL  Target practice Captured during the testing phase that would refine Webb’s incredible imaging powers, this image of Jupiter honed the telescope’s instruments before science operations officially began on July 12. In it we can see the planet’s distinctive rings, as well as its moons Europa, Thebe and Metis. We can also see a region of dead pixels on one of the camera’s detectors, the black spot on the second image.  Five for the price of one Webb’s largest image yet, Stephan’s Quintet – a group of merging galaxies – covers an area one-fifth the size of the Moon. The telescope’s near- and mid- infrared instruments combined to reveal never-before-seen features within the galaxies, as well as shockwaves caused by galaxy NGC 7318B smashing through the cluster. MORE ONLINE Explore a gallery of these and more stunning space images September 2022 BBC Sky at Night Magazine 9



JAMES WEBB SPACE TELESCOPE SPECIAL The latest astronomy and space news, written by Ezzy Pearson BULLETIN JWST unveils its first images The incredible pictures took just one week of observing time to create After decades of waiting, the James Webb Space Telescope – all of which were taken within a single week of observing time. (JWST) has released its first scientific images to the public. “The Hubble Deep Field was two weeks of continuous “Today, we present humanity with a ground-breaking new work with Hubble. We did [ours] before breakfast,” says Jane view of the cosmos – a view the world has never seen before,” Rigby, operational project scientist for JWST. “The amazing said NASA administrator Bill Nelson. thing about Webb is the speed with which we can churn out discoveries.” On 11 July, President Joe Biden was given an advance view of the images, and thanked “the team at NASA for once again But while the images stunned the world, a report on JWST’s showing who we are”. performance revealed an unexpectedly large micrometorite strike in May has caused a “significant uncorrectable change” The first deep-field image was released that evening. The to one of the mirror segments. Fortunately it only affects a next day, on 12 July, NASA released three more images, as well small area and JWST is still performing above expectations. as a spectra of exoplanet WASP-96b’s atmosphere, which showed clear signs of water. Before long, the images were To see the first images turn to page 6, and learn more about shared on news channels and social media the world over, as the science that JWST is set to deliver on page 28. people marvelled at the unprecedented detail in the images webbtelescope.org Þ President Biden reveals the first full-colour image – the deepest infrared picture of the Universe yet – to a waiting world Comment I was wrong. Utterly, wonderfully wavelengths beyond what our Stephan’s Quintet on my phone. wrong. For over a decade, I’ve eyes can see inevitably makes the It turns out that a mirror six metres by Chris Lintott flinched when space agency press view blurrier. Setting up JWST as across is large – large enough to releases described JWST as the a machine capable of producing produce crystal-clear, pin-prick- NASA/BILL INGALLS successor to the Hubble Space images as beautiful as Hubble’s, sharp images to wow the world. Telescope. Though both are no matter their scientific utility, incredible tools for science, Hubble was asking for disappointment. Welcome to the infrared is best known for its spectacular Universe! Beautiful, isn’t it? images. JWST, though, is an Wrong, as I said. I have the infrared telescope; working with JWST image of the Carina Nebula Chris Lintott co-presents as my laptop background, and The Sky at Night September 2022 BBC Sky at Night Magazine 11

BULLETIN < An alluvial fan in Tian Shan, China. Similar fans (top) and river deltas (above) have been imaged on Mars Fans help reveal Mars’s watery past Water may have flowed across Mars for millions more years than previously thought VIEWSTOCK/ISTOCK/GETTY IMAGES, NASA/JPL/MSSS/ESA/DLR, NASA/JPL-CALTECH/MSSS/JHU-APL, A new study shows water could have the remains of river deltas and alluvial “We found that even though Mars NOIRLAB/NSF/AURA/M. GARLICK, X-RAY: NASA/CXC/UNIV. OF CAMBRIDGE/J. SISK-REYNÉS ET AL/ been flowing across the surface of Mars fans, which are created by sediment cooled over time, from global average RADIO: NSF/NRAO/VLA; OPTICAL: PANSTARRS, ESA/NASA/AVO/PAOLO PADOVANI as recently as 2.5 billion years ago. building up at the mouth of a narrow temperatures of –3˚C to about –15˚C, Although Mars is now an arid planet, its channel. Both require vast amounts of liquid water continued to be stable in surface is covered with geological flowing liquid water to form, so are a clear select areas,” says Morgan. “Together, evidence that it was once host to liquid indicator of its presence. By analysing these papers describe how Mars had water. What’s not so clear, however, is these, Morgan’s team found that as Mars liquid water in the form of rivers for a when this water disappeared. cooled and dried, liquid water was prolonged period, from about 3.6 to at increasingly restricted to the lower, least about 2.5 billion years ago.” “We’ve known for decades that Mars warmer regions of Mars. had rivers and lakes around 3.5 billion However, what the studies don’t show years ago, but in the past few years there In a second paper, the team compared was whether the planet’s climate stayed has been a growing body of evidence that the alluvial fans to previous work on the consistent during that time. substantial amounts of liquid water planet’s valley networks, which have continued to erode the Martian surface already been studied as indicators of past “We don’t believe Mars was wet for this for hundreds of millions of years,” says water. While the valleys were largely entire period,” says Morgan. “Conditions Alexander Morgan from the Planetary formed around 3.6 billion years ago, the that permitted liquid water may have Science Institute. alluvial fans formed more recently, 2.5 to been episodic, perhaps driven by changes 3 billion years ago, giving the researchers in Mars’s movements – such as axial tilt, To further investigate, Morgan has led a an insight into how the environment had orbital eccentricity or precession – or new study surveying fan-shaped features changed between those dates. volcanic activity.” seen across Mars. These are a mixture of www.psi.edu 12 BBC Sky at Night Magazine September 2022

NEWS IN BRIEF The enthusiast uncovered ILLUSTRATION a wealth of ultracool dwarfs ILLUSTRATION with companion stars Binary dwarfs found by amateur astronomer Extreme neutrinos The discovery continues a long tradition of citizen science Extragalactic neutrinos – highly energetic, difficult to Citizen scientist Frank Kiwy has helped find objects based on their colour. This led to the detect particles – probably 34 ultracool dwarf binary systems – doubling identification of 2,500 ultracool dwarfs, 34 of come from active galactic the number previously known. which were later found to have low-mass nuclei, where a galaxy’s companion stars. central black hole superheats Brown dwarfs are too small to be stars but the surrounding gas. These too large to be planets. Their faintness makes “I love the Backyard Worlds: Planet 9 project!” extreme conditions create them difficult to find, so the Backyard Worlds: says Kiwy. “Once you master the regular jets travelling at nearly the Planet 9 project asked over 100,000 members workflow you can dive much deeper into the speed of light, which shoot of the public to search images for signs of them subject. If you’re a person who is curious and out the particles with enough moving against background stars. Enthused by not afraid to learn something new, this might energy to cross the billions of the project, member Kiwy embarked on his own be the right thing for you.” lightyears between galaxies. quest, searching through the data to find www.zooniverse.org Radio radiation located Giant black hole is slower than its peers Astronomers have been The largest black hole to ever Research showed the monster using radio and infrared have its spin measured is quasar’s black hole spun more radiation to measure star turning slower than its smaller sluggishly than its slim siblings’ formation in galaxies for siblings, a new study reveals. 50 years, but have only now holes between one and 10 “The moderate spin for this worked out where this “Every black hole can be solar masses. It’s thought that ultra-massive object may be a radiation comes from. Young defined by just two numbers: these monsters grow by testament to the violent, massive stars heat up the its spin and its mass,” says merging together, which chaotic history of the Universe’s surrounding gas, causing it to Julia Sisk-Reynes from the disrupts their rotation, slowing biggest black holes,” says glow in the infrared, then University of Cambridge, who them down. The more they co-author James Matthews. explode in supernovae that led the new research. “While grow, the more they slow. www.ast.cam.ac.uk create radio waves. that sounds fairly simple, figuring those values out for NLCs on the rise most black holes has proved incredibly difficult.” This July was a bumper month for noctilucent clouds, The black hole at the heart with sightings extending far of quasar H1821+643 in the further south than normal, constellation Draco is a while NASA’s AIM spacecraft colossal 30 billion solar measured the strongest NLC masses, around 10,000 times activity in over 15 years. The more massive than the Milky number of clouds has been Way’s central black hole. rising in recent years, with Astronomers measured its spin greenhouse gases and water by looking at X-rays bouncing vapour from rocket launches off the material surrounding it, being potential causes. and found its rotation to be about half the speed of black September 2022 BBC Sky at Night Magazine 13

NEWS IN BULLETIN BRIEF Solar storms cause train delays Sun’s activity found to mimic the system used for train signalling Small impacts ‘Your train has been delayed due to a bombarded Moon signalling failure’ is a phrase commuters will be all too familiar with. While most of us might lay The early Moon may have the blame on snow or rain, a recent report sustained twice as many suggests another type of weather could also be impacts as previously at fault – space weather. thought. Measurements taken by NASA’s Gravity Train signalling systems use electric currents Recovery and Interior in the rails to determine if a train is present on a Laboratory spacecraft have given section of track, showing a red light if it shown that between 4.3 to detects one. However, solar storms also cause 3.8 billion years ago, small similar currents to form in the rails and it only meteors compacted the takes a moderate event to trigger a red signal, lunar surface. This suggests even when there’s no train present. the number of craters seen today could represent only “We are now working on looking at the case half the number of strikes. where trains are present on the line, and how strong a solar storm needs to be to turn a red Russia to withdraw signal back to green,” says Cameron Patterson from the ISS in 2024 from Lancaster University, who investigated the phenomenon. “That’s a far more hazardous Roscosmos, the Russian scenario, potentially leading to crashes!” space agency, has officially www.lancaster.ac.uk STEVE MARSH, NASA, INTERNATIONAL GEMINI OBSERVATORY/NOIRLAB/NSF/AURAannounced that it will leaveÞ Solar flares and coronal mass ejections – the ILLUSTRATIONthe ISS in 2024 once its existing agreement runs out. possible culprits for train signalling glitches Newly appointed agency chief Yuri Borisov stated Fossil galaxy lies near Andromeda Russia will now focus on building its own station. The faint smudge suggesting they was found to be a first formed in the UK space launch due galactic relic of the very early Universe, early Universe before later Virgin Orbit will launch its generations of stars next satellite from the UK Pegasus V seeded the cosmos later this year. The satellite with more elements. will be carried into orbit on A relic of one of the first ever galaxies has board a modified Boeing 747 been discovered on the outer fringes of the “This discovery from Spaceport Cornwall. Andromeda Galaxy. marks the first time This is one of several a galaxy this faint planned UK launches as part The galaxy, called Pegasus V, was detected has been found of the government’s aim to during the DESI Legacy Imaging Survey, a around the become the first European systematic search of Andromeda’s dwarfs, but Andromeda Galaxy country to launch a satellite it was eagle-eyed amateur astronomer using an from home soil in 2022. Giuseppe Donatiello that spotted a strange astronomical survey that wasn’t specifically smudge in one of the images. Follow-up designed for the task,” says Michelle Collins observations revealed this was a faint galaxy. from the University of Surrey, who led the research. “We hope that further study of The stars of Pegasus V lack heavy elements, Pegasus V’s chemical properties will provide clues into the earliest periods of star formation in the Universe. This little fossil galaxy from the early Universe may help us understand how galaxies form and whether our understanding of dark matter is correct.” www.legacysurvey.org 14 BBC Sky at Night Magazine September 2022

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Our experts examine the hottest new research CUTTING EDGE An unknown object occurring within the north tropical zone. The peak slams into Jupiter, causing apparent brightness of the flash in the visible band the most energetic flash was mag. 4.7, equivalent to an absolute magnitude seen this century of –29.0: roughly 300 times brighter than the Sun at Jupiter. And because their PONCOTS system can observe with a high frame rate across three wavelengths simultaneously, they were able to record this impact flash with unprecedented detail. How big was the bang? From the three light curves, they calculated that the temperature of the resultant fireball in the upper atmosphere of Jupiter was over 8,000°C. The impactor would have struck with a kinetic energy of around 7 million billion joules – an explosion equivalent to two megatons of TNT. This is comparable to that of the Tunguska event, when a meteoroid exploded over eastern Siberia in 1908 Fireball over Jupiter and flattened over 2,000 square kilometres of forest: outshines the Sun the largest impact event on Earth in recorded The bright flash was caused by an history. From the energy of the Jovian impact the size of the Tunguska event “The fireball impact, the impactor was estimated T he spectacular collision of the comet was over 8,000°C. to have a mass of around four million Shoemaker–Levy 9 into Jupiter in 1994 kilogrammes and a diameter of was watched closely by observatories and space probes, and made headlines The impactor would 16–31 metres. around the world. Since 2010, six have struck with an This is the most energetic impact impact flashes on Jupiter have been explosion equivalent serendipitously observed, including by amateur flash observed in the Solar System astronomers. A simple brightness measurement to two megatons since Shoemaker–Levy 9. Those allows for an estimate of the energy of such impacts, created a string of giant dark but far more accurate calculations can be made if they are recorded at several different wavelengths. of TNT” patches in the Jovian atmosphere visible from Earth, scars that persisted Ko Arimatsu, at the Astronomical Observatory, Kyoto University, and his colleagues have been using for months. Arimatsu and his team were the Planetary ObservatioN Camera for Optical Transient Surveys (PONCOTS), dedicated to hopeful that their detected impact might also monitoring flashes on Jupiter. The system is made up of a 28cm Schmidt-Cassegrain telescope on a have left observable marks, but their follow-up rooftop at the university, equipped with two CMOS cameras. This setup allows the astronomers to observation 16 minutes after the event could find observe flashes on Jupiter at three different wavelengths simultaneously: the V visible band in the no signs. The Juno spacecraft, in orbit around the yellow and two near-infrared bands. planet, was able to observe the impact site 28 On 15 October 2021, Arimatsu and his team observed a particularly bright impact flash on Jupiter, hours later, but even with such a front-row view it too failed to spot any clear debris features. Arimatsu KO ARIMATSU, AGOR2012/ANASTASIIA_M/ISTOCK/GETTY IMAGES speculates that this could be due to the fact that their impactor was smaller than those of Shoemaker–Levy 9 and so any impact features were much more limited and shortlived. Based on their observations, Arimatsu estimates Prof Lewis Dartnell that such Tunguska-like impact events on Jupiter is an astrobiologist occur roughly once a year – hundreds to thousands at the University of times more often than on Earth – and so they’re of Westminster waiting eagerly to catch the next one! Lewis Dartnell was reading… Detection of an Extremely Large Impact Flash on Jupiter by High-cadence Multiwavelength Observations by Ko Arimatsu et al. Read it online at: https://arxiv.org/abs/2206.01050 16 BBC Sky at Night Magazine September 2022

CUTTING EDGE Is ET phoning home? the source of a real signal to be close to stationary relative to the Sun, so we can pay attention only to those signals. A few candidate events are found in Gravitational lensing could help both the frequency bands that the astronomers boost extraterrestrial signals targeted, but close inspection shows them to be false between the stars alarms. The brightest in a range of frequencies known as the L band, for example, seems to be Prof Chris Lintott chatter from an Iridium communications satellite. W here should we look for is an astrophysicist Despite this non-detection, the technique has aliens? For more than and co-presenter 50 years, the usual answer on The Sky at Night promise. After all, it’s only one set of observations. has been ‘among the stars’, with the search for “It’s possible Perhaps our beacon reports to the Alpha Centaurians extraterrestrial intelligence to imagine an only once a week, or once a year. Or perhaps Alpha (SETI) focused on scanning the skies with large radio telescopes. That might be changing, as a Centauri is the wrong target. It’s possible, the authors say, to imagine an interstellar communications network, with relay satellites positioned throughout the Galaxy to new generation of SETI experiments and interstellar forward messages via gravitational lensing. In scientists join the hunt. communications network, with relay such a system, multiple star systems like Some want to look for alien artefacts in satellites positioned the Solar System, a plan sure to appeal to Alpha Centauri, with its two bright anyone who remembers 2001: A Space components plus faint Proxima, are poor choices, forcing their beacons to adjust Odyssey’s sinister black monolith. The trouble throughout the position constantly as the stars move. Much is that there is a lot of Solar System to Galaxy” better to look for signals pinging between investigate, and so it helps in your search if you nodes anchored on more boring stars – just like have some idea of what the aliens might be up to. our Sun. We should probably keep looking. The authors of this month’s paper start with the idea that any alien probes that were exploring our Want to send a neighbourhood would need to report back to their message to a nearby home system. Doing that, though, is hard, requiring star? Aim for our Sun what is presumably a modest probe to use an and transmit around it enormous amount of power to send a detectable signal over interstellar distances. Any sensible alien spacecraft engineers would look for a shortcut. Luckily, they should know that radio waves, like any electromagnetic radiation, can be lensed and magnified by the Sun’s gravity. Position a probe about 500 times the Earth–Sun distance behind the Sun, exactly in line with your home star, and it should be possible to get a report on Earth’s status back home with transmitters not much more powerful than those our own spacecraft carry today. If we pay attention when Earth crosses the region between the Sun and a target star, looking for any stray signals with radio telescopes, we might be able to eavesdrop on their communications. This paper, ILLUSTRATION the result of a summer project for some lucky undergraduates at Penn State University’s SETI centre, used the Green Bank Telescope in radio-quiet West Virginia to do just that. As ever with a SETI project, the biggest problem is Chris Lintott was reading… A Search for Radio Technosignatures at the Solar Gravitational Lens Targeting Alpha Centauri by Nick Tusay et al distinguishing what might be an artificial Read it online at: https://arxiv.org/abs/2206.14807 transmission from all the noise and clutter generated by our terrestrial civilisation. In this case, we expect September 2022 BBC Sky at Night Magazine 17

The Sky at Night TV show, past, present and future INSIDE THE SKY AT NIGHT As the first images from JWST Mikako has secured come in, Mikako Matsuura recalls time to observe Type II how she won not just one but two observing opportunities on the supernova SN 1987a world’s most anticipated telescope with the JWST With a mirror area 64 times Mikako addressing bigger than NASA’s previous the International infrared space telescope and Astronomical instruments up to 100 times Union in Brazil more sensitive, the James Webb Space Telescope The Butterfly Nebula (JWST) will allow us to take deeper and sharper NGC 6302 will be the target images of astronomical objects than ever before. of her second study ESA/HUBBLE/NASA, MIKAKO MATSUURA, NASA/ESA AND J. Although JWST is a NASA-led mission with KASTNER (RIT), BBC, SARAVUTVANSET/ISTOCK/GETTY IMAGES involvement from the European and Canadian space agencies, astronomers from any country can apply for observing time. When the call for proposals went out in 2018, I decided to request observations of Supernova 1987A. It’s the closest supernova explosion in the last 400 years, located 170,000 lightyears away from Earth. We’ve been able to see the fast shock waves from the supernova, travelling at 1,000km/s, as they expand and destroy the surrounding material. Writing an observing proposal is time-consuming. It takes up to two weeks, requiring detailed simulations of how much time is needed. But just as I finished writing the proposal and went to click the submit button, an e-mail from NASA arrived announcing the launch was delayed. How disappointing! JWST is a $10bn space mission, so of course it’s better to be safe than sorry. But still, it was disheartening. NASA reopened proposals two years later. When I looked back at my work, I realised it lacked a punchline: “Why do we need the JWST for this observation?” It’s a key point that should be included in any observing proposals, but it was missing. I realised JWST will be able to capture how blast shock waves break up dust, which we couldn’t see before. Made it, with time to spare Then, three days before the deadline, when everything was sorted, I realised something was wrong in my exposure time simulation. I started panicking, but it’s always helpful to have collaborators. My colleagues Tea Temim and Martha Boyer from the Space Telescope Science Institute redid the simulations from scratch and we were able to submit on time. Back in 2018, I’d also wanted to observe planetary nebula NGC 6302, but it would have been far too 18 BBC Sky at Night Magazine September 2022

JAMES WEBB SPACE TELESCOPE SPECIAL THE SKY AT NIGHT WANTS YOUR QUESTIONS As part of the British Science Festival 2022, The Sky at Night is recording a special programme on 14 September, when the presenters and special guests will be answering questions from viewers. If you have a question – on anything from space travel and technology to astronomy and astrophysics – the programme team want to hear from you at: [email protected] Dr Mikako demanding to write two proposals. However, as I’d Another six months passed. It was April 2021, a Matsuura is an done most of the work for the Supernova 1987A sunny day just before Easter. My husband and I took astrophysicist at submission back in 2018, I was able to write a new an extra day off and went for a drive when suddenly Cardiff University proposal for NGC 6302 in 2020. my phone notified me the JWST selection results working in infrared were out. I was so scared to open the emails, not and millimetre It is always good to share ideas and get knowing if they would say “Congratulations!” or observations constructive criticism, and when I did, Rens Waters “We’re very sorry”. from Groningen and Eric Lagadec from Nice said, “It‘s a good idea, but there are too many details”. After I came back home, I took a breath and Sometimes if you are in your own world, you don’t opened them. Both were accepted. Unbelievable! really see your own faults: you lose the bigger picture. At the same time, the responsibility to make these Rens re-wrote the first key introduction paragraph, observing programs successful now fell on my guiding the scientific case, and so the second shoulders. And now, as the data arrives, it’s time for proposal was submitted. the next round of challenges to begin. Looking back: SEPTEMBER The Sky at Night 19 September 1957 How to Photograph the Universe On 19 September the end, naming So you enjoy observing the night sky, watching the planets, stars and other 1957’s episode of The rights went to the objects through your telescope, but have you ever wanted to photograph what you Sky at Night, Patrick first report to reach see? In this month’s episode, Pete Lawrence is your guide as he and the Moore was joined on the International team explore astrophotography: what you need to get started and how you too can the show by a Astronomical Union, capture beautiful images of the cosmos. special guest: which was from 14-year-old Czech astronomer astronomer Clive Anotonín Mrkos. Hare. On 3 August, Now the comet is Four, 12 September, 10pm (first repeat Hare had been one Þ Young astronomer Clive Hare tells known as Comet will be on Four, 15 September, time tbc) of the first people to C/1957 P1 Mrkos. It observe a new comet Patrick Moore about his sighting would eventually Check www.bbc.co.uk/skyatnight streaking across the sky in the reach a brightness of mag. +1.0 on for up-to-date information constellation of Gemini. Being a 4 August and stretched out across 5° of member of the British Astronomical sky at its longest. After that, the comet Association, Hare knew to report his slowly faded, passing through the findings, noting that the comet was of constellation of Ursa Major to Coma equal brightness to nearby Pollux (mag Berenices, and was eventually lost from +1.5) and around 2° long. view in Virgo at the end of September. As the BAA raced to release a report, Hare’s appearance on the show was it soon became clear that astronomers part of Patrick’s lifelong belief that all over the world were also making the anyone could be an astronomer, same discovery. The first sighting was regardless of age, and his observation traced back to Japanese astronomer remains a prime example of the major S Kuragano on 29 July, but several other role amateur astronomers play in the Þ Find out how you can get started in astro astronomers also spotted the comet. In world of astronomical discovery. imaging in this month’s episode September 2022 BBC Sky at Night Magazine 19

Emails – Letters – Tweets – Facebook – Instagram – Kit questions MESSAGE OF THE INTERACTIVE MONTH Email us at [email protected] This month’s top prize: Making good times two Philip’s titles with a DIY sundial The ‘Message Thank you very much indeed for publishing of the Month’ Mary McIntyre’s instructions for making an writer will equatorial sundial (DIY Astronomy, ‘Make a receive a bundle paper equatorial sundial’, August 2022 issue, of two top titles courtesy page 74). The timing was perfect as I needed of astronomy publisher to occupy my granddaughter Akira on the first Philip’s: Nigel Henbest’s day of the summer holidays. It proved to be a Stargazing 2022 and Robin tremendous learning exercise for both of us Scagell’s Guide to the and we were delighted when the Sun came Northern Constellations out just before Akira’s bedtime and correctly showed the time as almost 6pm GMT (7pm Winner’s details will be passed on to BST – or bedtime). The next job is to build Octopus Publishing to fulfil the prize a weatherproof version for the garden! Peter and Akira Bartram, via email We’re delighted to see the sundial in action, Þ Akira’s paper and drinking straw timepiece Peter and Akira, and providing the timing for important points in the day like bedtime! It’s a great little project this one, easy to do and a fun activity for all ages. – Ed. Tweet Number crunching to our numeration)! A listing of Archimedes’s values for interplanetary Cath Adams Thank you for all you are doing for a great distances has come down to us, but @CathAdams1973 • Jul 19 and long-lived magazine. In July’s book unfortunately through a garbled @skyatnightmag I’ve been reviews section, I was interested to read secondary source. sitting outside stargazing, the that author Antonio Padilla calculates the Paul Mohr, Corrandulla, County air is cooler but sadly no breeze. biggest number in the Universe to be 1061 Galway, Ireland Here is the International Space (review of Fantastic Numbers and Where Station passing over my house to Find Them, page 94). In my forthcoming Mystery object at 23:06 taken using @ book on the history of Greek astronomy, NightCapApp on an iPhone. A String of Pearls, I summarise I was wondering if you could help me to #InternationalSpaceStation Archimedes’s calculation of the size of the identify something in the night sky on heliocentric Universe, and follow up by Friday 29 April at 23:07pm. I’ve tried to do looking at this brilliant mathematician’s my own research but nothing conclusive zest for exploring even larger numbers. has materialised. It travelled south to Not content with numbers restricted to north, looked like a small, spherical white the size of the Universe, Archimedes full Moon, but was hazy in its appearance continued to construct a perfectly logical (its core was brighter). I tracked it from counting structure that soared way overhead until it disappeared below the beyond human imagining until he finally horizon line. I was taking shots of the decided to call a halt when he reached Heart and Soul Nebula and found out the 1080,000,000,000,000,000 (converted from Greek following morning that this object passed right through one of the images. The 20 BBC Sky at Night Magazine September 2022

The strange object caused a hazy streak in Ian’s photo SCOPE DOCTOR Our equipment specialist cures your optical ailments and technical maladies With Steve Richards Email your queries to [email protected] photos were taken in Wales. 13 billion years old. I assume Should I insulate my observatory? I’ve seen and imaged many a that these galaxies are not shooting star and the ISS but stationary and while the light KEVIN PRIOR never seen anything as large from them has been travelling as this. Any ideas? Thanks. towards us, the galaxies Mitigating the effects of Ian Sutton, via email themselves have moved and are thus today no longer large temperature This was the deorbit burn of a where they appear to us to be. Russian Angara 1.2 rocket stage But if we are seeing them fluctuations to aid cooling launched earlier that evening. where they were shortly after Nice catch, Ian! – Ed. the Big Bang then why are down times and reduce the they all so far apart? Why Moving picture aren’t they clustered together, problems of dew formation BARRY WILSON relatively speaking, near to the I am puzzled and would be centre of the event? are excellent reasons for grateful if someone could Dr Giles Camplin, council answer a question for me. member of the Airship installing an observatory. According to the television Association, London reports, the images that we But a bare observatory have seen from the James The current theory to explain Webb Space Telescope include why objects like galaxies were > won’t solve these issues Þ A wooden roll-off-roof some galaxies that are about completely, so it is worth making it as temperature- observatory is easier to insulate stable as possible. than a metal-domed structure Wooden roll-off-roof designs are much easier to insulate than metal or fibreglass domed observatories, and wood construction already offers an advantage in temperature stabilisation. However, there is an argument for not using additional insulation as this could lead to heat retention, which is radiated later in the day causing unwanted air ON FACEBOOK currents that can spoil the view. You can avoid this by opening WE ASKED: what do you think of JWST’s new up the observatory earlier, in advance of an observing session. image of Stephan’s Quintet (see page 9)? For a roll-off-roof design, a combination of insulation and Tim Jardine A galaxy group I have viewed and imaged many times, but to see it like this is just amazing. good ventilation is likely to be a good solution and a pale- Jon Mcinerney You wait 13 billion years, and then five coloured (ideally white) domed observatory with good galaxies turn up at once. ventilation will also yield good results. Either solution will Linda Wood Field I think it’s amazing and beyond comprehension. benefit greatly from the use of a desiccant dehumidifier. Michael Page You get different information when viewing the Steve’s top tip Universe at different light wavelengths. Infrared light can pass through the gas and dust clouds that Hubble can see in How do I set up a finderscope? visible light, so Webb allows the scientists to see the objects that are inside or behind those dust clouds. A finderscope is a small, wide-field scope that helps you find targets in the night sky. It should be firmly mounted to the Frank Michael Knight Game changing for the future of main telescope tube, normally using a small dovetail bar. science. Truly stunning. Finderscopes should be accurately aligned with the telescope in two stages. Start by pointing the telescope at a distant Lindy Lou Looks like part of a paw. object during the daytime (NOT the Sun), and centre it in the eyepiece. Next, without moving the telescope, centre the Peter Parr Gotta be intelligent life out there. same object on the finderscope’s crosshairs by adjusting the three adjustment screws. To align at night, centre a bright star Jason Philip Hall Astonishing! Pure and simple. This in your eyepiece, then centre the same star on the instrument will change everything. finderscope’s crosshairs using the screws on its mount. Ed Shendell Absolutely amazed at the images coming from Steve Richards is a keen astro imager and an the James Webb Telescope. Looking back in time 13.5 billion astronomy equipment expert years ago! The impact this will have on locating lost luggage cannot be underestimated. September 2022 BBC Sky at Night Magazine 21

BBC Sky at Night Magazine is published by Our Media Ltd INTERACTIVE (an Immediate Group Company) under licence from BBC Studios, which helps fund new BBC programmes. > already so far apart so soon after the Big Instagram Bang is called Inflation. It proposes a EDITORIAL photoknoxy • 15 July period of immensely rapid, exponential Editor Chris Bramley Another view of Wednesday’s rising full Art Editor Steve Marsh expansion in the Universe during its first Moon (aka the ‘Buck Moon’ or Production Editor Jane Williamson few moments. – Ed. supermoon) with the ruins of Mow Cop Features Editor Ezzy Pearson castle silhouetted in the foreground. Content Editor Iain Todd Room to grow #cheshire #fullmoon #moonrise Reviews Editor Paul Money #buckmoon #lunarphotography I have a question about the expanding #nightsky #bbcnorthwest CONTRIBUTORS Universe, which I haven’t seen an answer @bbcskyatnightmag @canonuk @ to yet. If the Universe is expanding, where nationaltrust @bbcnorthwest Stuart Atkinson, Mark Bowyer, Melissa Brobby, is it expanding to? Is there something Charlotte Daniels, Lewis Dartnell, Glenn Dawes, Ben outside the Universe as well? Surely it Evans, Ian Evenden, Pete Lawrence, Scott Levine, Chris cannot expand into nothingness. If there Lintott, Mikako Matsuura, Paul Money, Martin Pugh, is something outside the Universe, is it Mark Parrish, Katrin Raynor-Evans, Steve Richards, possible that it’s another Universe? Giles Sparrow, Colin Stuart, Stephen Tonkin, Tom Tivadar Tot, Serbia Urbain, Jenny Winder We’re not entirely sure, but the leading idea providing the ‘centripetal’ force required ADVERTISING SALES for the Earth to follow its orbit. This is that it is expanding into dimensions we force is not balanced by any other force, Advertising Manager Andy Williams and indeed is an unbalanced force. If this +44 (0)117 300 8803, [email protected] can’t perceive. Imagine a person living in force was not present, the Earth would Inserts Laurence Robertson +353 (0)87 690 2208 merely continue in a straight line at a two dimensions on the surface of a balloon constant speed. PRODUCTION Steven Mitchell, via email that’s inflating – they can see the space Production Director Sarah Powell While centrifugal force is an ‘apparent’ Production Coordinator Lauren Morris around them getting larger, but not the force, which doesn’t actually exist like Ad Services Manager Paul Thornton third dimension it’s expanding into. – Ed. centripetal force does, astronomers use it Ad Coordinator Charles Thurlow as a common short-hand as it’s an easily Ad Designer Parvin Sepehr Force fault understandable term. – Ed. Reprographics Tony Hunt, Chris Sutch In the article ‘Jupiter’s Asteroid Swarms’ LICENSING (July 2022 issue, Cutting Edge) it states that, “the gravitation of the Sun pulling Director of Licensing and Syndication Tim Hudson in and the centrifugal force of our motion International Partners’ Manager Anna Genevier flinging out act to balance each other out”. As a physics graduate and teacher, MARKETING I know that this statement is incorrect. There is no such thing as ‘centrifugal Head of Marketing Jacky Perales-Morris force’. Our planet stays in orbit due to the Marketing Executive Kellie Lane gravitational force towards the Sun Press and PR Manager Emma Cooney SOCIETY IN FOCUS Þ YAS observatory in 1978 PUBLISHING & MANAGEMENT York Astronomical society (YAS) was there and using the old telescope, fortified Associate Publisher Rob Brock pleased to celebrate its 50th anniversary by runs to the chip shop and the pub! In Managing Director Andrew Davies this year, and we’re looking forward to the last 50 years we’ve had six Group Managing Director Andy Marshall continuing our success with a series of observatory sites and five different CEO Tom Bureau events planned for this autumn. meeting places. Today we have an observatory at a farm east of York where BBC STUDIOS, UK PUBLISHING YAS was founded in 1972 in response to we hold meetings and public events. the excitement generated by the Apollo Extract from The Definitive History of Chair, Editorial Review Boards Nicholas Brett programme. In April that year a group of the York Astronomical Society (So Far!), Managing Director, Consumer Products observers from Stamford Bridge formed by Martin Dawson and Licensing Stephen Davies the society, initially meeting at their local > yorkastro.org.uk Director, Magazines and pub or a garage belonging to one of the Consumer Products Mandy Thwaites members. Later meetings were held at Compliance Manager Cameron McEwan York Railway Institute, where two rooms UK Publishing Coordinator Eva Abramik with open coal fires and large tables were [email protected]; www.bbcstudios.com on offer. Discussions included the 10 November 1973 Mercury transit and EDITORIAL REVIEW BOARD Comet Kohoutek. One of our first observatories was in a derelict brick Andrew Cohen, Head, BBC Studios Science Unit; building, part of the abandoned hospital Martin Smith, Executive Editor, BBC Radio Science Unit; site on the edge of Acaster Aerodrome Steve Crabtree, Executive Producer, BBC Studios; dating from WW2. We enjoyed camping Dr Erica McAlister; Dr Jessica Wade SUBSCRIPTION RATES Annual subscription rates (inc. P&P): UK cheque/credit card £62.40; Europe & Eire Airmail £75; rest of world airmail £85. To order, call 03330 162119 (UK); overseas +44 (0)1604 973727 We abide by IPSO’s rules and regulations. To give feedback about our magazines, please visit immediate.co.uk, email [email protected] or write to The Editor, BBC Sky at Night Magazine, Our Media Ltd, Eagle House, Bristol, BS1 4ST. Audit Bureau of Circulations 23,082 (combined; Jan–Dec 2021) © Our Media Ltd (an Immediate Group Company) 2022 ISSN 1745-9869 All rights reserved. No part of BBC Sky at Night Magazine may be reproduced in any form or by means either wholly or in part, without prior written permission of the publisher. Not to be re-sold, lent or hired out or otherwise disposed of by way of trade at more than the recommended retail price (subject to VAT in the Republic of Ireland) or in mutilated condition. Our Media Ltd is working to ensure that all of its paper is sourced from well- managed forests. This magazine is printed on Forest Stewardship Council (FSC) certified paper. This magazine can be recycled, for use in newspapers and packaging. 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We pick the best live and virtual astronomy events and resources this month WHAT’S ON PICK OF THE MONTH Discovering and Imaging Þ The Sky at Night presenter Chris Lintott’s talk is open to the public and new members Planetary Nebulae How to be Surprised by the Universe Augustine United Church, Edinburgh, 9 September, 7:30pm Clanfield Memorial Hall, near Portsmouth, 9 September, 8pm Join the Astronomical Society of Edinburgh for a talk on why these dying Astrophysicist and The Sky at Night on the observatory until 1972. From stars are of such interest to cosmologists, presenter Chris Lintott will be delivering mysterious radio signals to spectacular and how you can go about observing and a talk entitled ‘How to be Surprised supernovae, the Universe keeps finding imaging them for yourself. by the Universe’ to the Hampshire new ways to astonish us. Chris Lintott www.astronomyedinburgh.org Astronomical Group at the Memorial Hall of the University of Oxford explains why near its Clanfield Observatory (above). we should keep our eyes peeled for the Astronomy Festival Situated on the edge of the South Downs unusual, and what to do when you think National Park, the group was founded in you’ve found an alien civilisation. Entry Observatory Science Centre, Portsmouth in 1960 but work didn’t begin £3 for non-members. hantsastro.org.uk Herstmonceux, E Sussex, 2–4 September RICHARD JUDD, FRAS, CHRISTOPH KALTSEIS/CCDGUIDE.COM A weekend under the stars, featuring Stargazing weekend under the stars in one of the world’s best stargazing evenings with telescopes large dark-sky regions. Events individually and small, plus lectures, planetarium Island Planetarium, Yarmouth, priced, ranging from free to £10. shows, solar observing, trade stands and Isle of Wight, 23–25 September www.breconbeacons.org/stargazing a pub quiz. Tickets from £11.50. This weekend includes evening www.the-observatory.org/events stargazing, daytime observations of the Herschel 200 Sun, visits to the observatory or Needles Super Telescope: Mission Battery Space Display, plus talks and Herschel Museum of Astronomy, to the Edge of the Universe teaching sessions. £75 per person. Bath, until 31 December www.islandastronomy.co.uk A major exhibition brings new collections Online to the Bath home of celebrated 18th- This Horizon documentary explores the Brecon Dark Sky Festival century astronomer William Herschel for inside story of the James Webb Space the 200th anniversary of his death. Adult Telescope. BBC iPlayer Brecon Beacons, 24–25 September tickets £9.50, kids’ tickets £4.50. Enjoy planetarium shows, stargazing, www.herschelmuseum.org.uk Stargazing session telescope observing and paddle boarding Durlston Country Park, Swanage, Dorset, 4 September, 8:15pm Join the astronomers from the Wessex Astronomical Society for an observing session at their fantastic observatory located in Durlston Country Park. This event includes observing the Moon, Jupiter, Saturn and summer constellations. A small fee is payable. wessex-astro.org.uk September 2022 BBC Sky at Night Magazine 23

Join our BAA meeting in Elgin, Scotland A Sun & its Solar System Featuring talks by: PROF CLARE PARNELL DR JOHN MASON SANDRA BRANTINGHAM DENIS BUCZYNSKI LYN SMITH NICK JAMES DR PAUL ABEL Friday–Sunday, September 9–11 Book in advance at elgin-2022.eventbrite.co.uk British Astronomical Association Image: Alan Tough A TOUGH MULTI-USE WAISTCOAT visit www.britastro.org The R045X Safari Waistcoat benefits from no less than 10 pockets, making this a ‘must have’ garment for anglers, gardeners and photographers alike www.workguardworkwear.com www.thepoltimoreinnnorthmolton.co.uk An award-winning country pub [email protected] An Exmoor National Park Dark Skies Friendly Business 01598 740338 Fully equipped observatory with roll off roof Pub with great beer and food. Superb Accommodation Regular Programme of Stargazing Events and Education Open 7 days a week all year round

The amateur astronomer’s forum FIELD OF VIEW An ode to the Summer Triangle Scott Levine has a soft spot for the superstar asterism of the warmer months Deneb Visible for most of the northeast horizon in mid-May, with Deneb (Alpha (α) CYGNUS year, the three bright Cygni) and Altair (Alpha (α) Aquilae) close behind. stars of the Triangle are As the weeks passed, I ran into that same highest in summer neighbour from time to time. Stars rise four minutes earlier each night, which doesn’t seem like much, but LYRA little by little these minutes add up. By August, as we talked about racing from work to soccer games, then Vega home to get dinner on and off the table, the Triangle rose up to where it might be easier – and safer – to lie VULPECULA on our backs in the street than to twist our necks to find it. It would be January before the minutes carried EQUULEUS those stars out through the western dusk. SAGITTA Altair and Vega are just across town as things go: only about 16 and 25 lightyears away, which helps DELPHINUS them appear unusually bright in our sky. Deneb, though, is more challenging. It’s one of the most Altair distant star systems we can see with our unaided eye: over 2,000 lightyears away. So it’s not near the AQUILA others at all, but far behind them. The Deneb we see is much more subdued than Altair and Vega. If we’re Scott Levine is On a breezy night when I was able to see it so brightly from so far away, imagine a naked-eye still new to my neighbourhood, what it would be like if it were much closer. stargazer and an I slipped out into the dark, astronomy writer stumbled to my favourite north- Let’s consider the other stars within and near the based in New York’s facing spot and looked up. My Triangle: the unlabelled, understated, anonymous Hudson Valley hopes for quiet were dashed when stars. Other than Vega, all of the constellation Lyra’s my chatty neighbour joined me, but as early-season stars are dim, as are those in Vulpecula (the Fox), crickets chirped, we shifted our gaze between Sagitta (the Arrow), Delphinus (the Dolphin) and STELLARIUM.ORG branches, stared into one of my favourite patches of Equuleus (the little horse), the group of small the sky and talked about the stars, and about nothing. constellations that carve a path through the Triangle. These stars are all listed and catalogued, but many Growing up in a dense suburb, not far from a rail aren’t named. I love to look up and think about what’s station and small airport, the Summer Triangle out there – not just what we know, but also what we asterism was one of the few groups of stars that don’t – and imagine what we’ll learn one day. pierced the sky-glow enough that I could see it easily. Its corner stars are among the night’s brightest, but In dark-sky places, far behind Deneb, we can even the shape they sketch is compact and sleek, like a see the soft glow of countless stars running through sensible sedan car. I’ve loved it ever since. Blue-white the Triangle, their light blurred together by many Vega (Alpha (α) Lyrae) arrives just above the thousands of empty lightyears: the band of our Milky Way Galaxy. As those early few weeks turned into years, and toddlers turned into teenagers, those moments with neighbours were some of my favourite times. My friend has since moved away, but you never know who you might run into tonight when out under the night sky. I hope you’ll look up… and try not to hurt your neck. September 2022 BBC Sky at Night Magazine 25

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A new age of discovery dawns as the long-awaited James Webb Space Telescope starts its mission begins its Colin Stuart (@skyponderer) is SCIENCE JOURNEY an astronomy author and speaker. As we gaze astonished at the James Webb Space Get a free e-book at Telescope’s first science images, Colin Stuart colinstuart.net/ takes a look at the questions it will answer over its ebook decade-long voyage of astronomical discovery 28 BBC Sky at Night Magazine September 2022

JAMES WEBB SPACE TELESCOPE SPECIAL 2 1Relative brightness 0 ALEX-MIT/ISTOCK/GETTY IMAGES, HARIKANE ET AL, NASA/ESA/CSA/STSCI, GLASS-Z13: NAIDU ET AL. 2022/ CASTELLANO ET AL. 2022/RAW DATA: T. TREU/UCLA/GLASS-JWST/NASA/CSA/ESA/STSCI/COLOR IMAGES: P. OESCH/G. BRAMMER/UNIVERSITY OF GENEVA/COSMIC DAWN CENTER/NBI/UNIVERSITY OF COPENHAGEN3.4 3.63.844.2 4.4 4.6 4.8 Wavelength of light (microns) Þ A single galaxy 13.1 billion years old is picked out of a field of hundreds and its light signature recorded by Webb’s NIRSpec instrument, a tool so sensitive it can mine information simultaneously from up to 150 individual galaxies that existed in the very early Universe What do the first stars look like? JWST will take us back to when the very first galaxies appeared Astronomers are always looking back into Þ Right out of the Hubble just isn’t up to that task – you the past. That’s because it takes time for need an entirely different kind of telescope. light to travel across the Universe. We don’t gate, JWST has see things as they are when the light found the oldest Enter JWST, which gathers infrared light arrives here, but as they were when galaxies ever seen, instead of the visible light to which our the light first departed. For distant like GLASS-z13 eyes, and Hubble, are sensitive. Infrared galaxies, the delay is millions and (above), 13.4 billion light is able to penetrate the dust that even billions of years. lightyears away can sometimes block our view of distant galaxies. So very distant galaxies were For the very first galaxies, also some of the first galaxies to there’s an even more fundamental form in the Universe. The Hubble problem with observing in visible Space Telescope revolutionised this light. The Universe has been area of research, finding thousands of expanding ever since its birth in the Big distant galaxies in a patch of sky so tiny Bang. Any light travelling through the that it could be covered by a grain of sand expanding Universe also gets stretched held at arm’s length. along the way. The light from the earliest The light from the most distant galaxy stars and galaxies has been stretched so observed before JWST – HD1 – took a much that it’s now slipped out of the visible staggering 13.1 billion years to reach Earth. spectrum and into the infrared. Now, for the first Astronomers are peering back to a time just 700 time, we’ll be able to see it. million years after the Big Bang. Yet they want to “It’s a chance for scientists to find out what typical look back even further to when the very first stars galaxies were like in the very early Universe and and galaxies appeared, estimated to be 100–200 maybe even find evidence of the very first stars ever million years after the Big Bang. They’re hunting the formed,” says Dr Emma Curtis-Lake, STFC Webb first light that lit up the so-called cosmic dark ages. Fellow at the University of Hertfordshire. > September 2022 BBC Sky at Night Magazine 29

How do galaxies form? JWST will show galaxies evolving, from billion of years ago up to today NIRCam and MIRI Imaging NIRSpec IFU Spectroscopy < The gas around a black hole within Stephan’s Quintet, its elements revealed by the telescope’s NIRSpec instrument Astronomers have already pointed it towards the supermassive black hole in the centre of one of four interacting galaxies in Stephan’s Quintet – NGC 7319. Black holes are thought to play a significant role in galactic evolution. The one in NGC 7319 has a mass equal to 24 million Suns, a number so big that it could only have formed by the mergers of lots of smaller black holes. The instrument has also been deployed further afield. “My favourite moment [from the first JWST data] was when they revealed the image showing the NIRSpec spectrum of a galaxy over 13 billion lightyears away,” says Curtis-Lake. “I’ve been impatient to find out how NIRSpec performs, and I can’t wait to get my hands on it and test our models for my own research,” she says. NIRSpec can simultaneously observe Wavelength of light hundreds of galaxies at once, looking for evidence that mergers are taking place. We live in the Milky Way galaxy – a vast stellar metropolis containing up to 400 billion stars. In turn there are up to two Hydrogen trillion other galaxies in the Universe. But Oxygen how are these vast structures made? Most astronomers tend to favour a so-called 8 Hydrogen ‘bottom-up’ approach in which a galaxy 6 forms from a series of mergers involving smaller groups of stars. Yet it is far from 4 2 0 2 34 Wavelength of light (microns) clear exactly how this process plays out. 6 Thankfully, JWST can help. 4 One of the early images from JWST 2 0 depicts Stephan’s Quintet, a collection of five galaxies, four of which are interacting 2 34 with one another. It shows us that a NASA/ESA/CSA/STSCI X 3, NASA/ESA AND THE HUBBLE HERITAGE TEAM (STSCI/AURA) Wavelength of light (microns) gravitational dance is underway as dust, Relative brightness gas and stars pirouette, pulled around 1 by each other’s gravity. One of the 0 galaxies – NGC 7318B – is producing huge shockwaves as it careers through the 2 34 Wavelength of light (microns) cluster. While the four interacting galaxies are relatively close to us at just under 300 6 million lightyears, studying them will help 4 astronomers understand what they’re 2 looking at when they turn JWST towards 0 more distant galaxies. 2 34 Wavelength of light (microns) One instrument aboard JWST is particularly well suited to this endeavour: Þ Emission lines never previously seen at such immense distances: even a quick analysis the Near-Infrared Spectrograph (NIRSpec). showed that galaxies in JWST’s first deep field (see page 8) were the oldest ever discovered 30 BBC Sky at Night Magazine September 2022

JAMES WEBB SPACE TELESCOPE SPECIAL How are stars and planets born? JWST will pierce the dust clouds to show us how worlds are made The modern world offers people many ways to þ The penetrative JWST will measure the different types of molecules look back on what we were like as children. It isn’t present in the inner disc such as water, carbon dioxide so easy with stars. Our Sun is in its middle age at power of JWST’s and methane – all associated with life in some way. 4.6 billion years old, but astronomers have found infrared is starkly If, for example, water is already present in and around some stars that are just one million years old revealed in this newborn rocky planets then that has promising – that’s the equivalent of being a 3.5-day-old baby comparison of the implications for our chances of finding water worlds in human terms. star nursery in the elsewhere in the Universe. Carina Nebula (left) Among the first images to be returned by JWST is with the image Astronomers have already been surprised by the a stunning look at the Carina Nebula, a cloud of gas taken by the Hubble variety of distant planets they’ve found to date. and dust where hot young stars are bursting into life. Space Telescope in Many stars are orbited by so-called super-Earths and These stellar infants are enshrouded by dust, which 2008 (right) mini-Neptunes – worlds partway in size between the obscures the view that visible light telescopes such Solar System’s rocky and gas planets. They seem to as Hubble can see, but which JWST pierces straight be the most common type of planet in the Universe through. The infrared reveals hidden stars, allowing and yet there are none in our own Solar System. astronomers to see how their radiation carves JWST could help us learn what these planets look through the surrounding gas. like and how they come about. The telescope will also be able to look at the Many of these observations can only be made planet-forming regions around stars. The outer parts in the infrared, which is absorbed by Earth’s of these protoplanetary discs have been studied atmosphere. It’s why these measurements require before using radio telescopes such as the Atacama a space-based telescope. JWST is also positioned Large Millimeter Array (ALMA) in Chile. However, 1.5 million kilometres away from Earth to avoid JWST’s greater resolution will mean it can peer into contamination from the infrared energy emitted by the inner part of the disc where rocky Earth-like Earth itself, giving it the clear view it needs to pick up planets may be forming. such miniscule detail from lightyears away. > JWST HUBBLE September 2022 BBC Sky at Night Magazine 31

Is there another Earth out there? JWST’s delve into exoplanet atmospheres will tell us just how common Earth-like planets are Perhaps the biggest question it’s possible to ask ILLUSTRATIONchemical elements and molecules swallow some about the Universe is: ‘Are we alone?’. JWST of the starlight, leaving distinctive gaps in the should allow us to make a giant leap forward in Þ Gas giant light JWST gathers up. finding the answer. There are some elements and molecules WASP-96b, where that swallow infrared light, so the gaps So far we’ve confirmed over 5,000 clear signs of water that result can’t be seen by telescopes exoplanets – planets in other solar were confirmed that only pick up visible light. Water systems. The bulk have been found using and methane – which is produced a technique called the transit method. by microbes on Earth – are two key Although distant planets are too small examples. Astronomers want to know and dim to be seen directly, we do see a how common they are among exoplanets temporary drop in the brightness of their host and how abundant they are on individual stars when a planet passes in front of them (an exoplanets. After all, the majority of Earth’s event called a transit). surface is covered in water. It’s a change in brightness of less than one per The first data release from JWST contained the cent, but it holds a wealth of information. As the transit of an exoplanet called WASP-96b, showing planet passes between us and the star, some of the clear signs of water blocking the light from the star. star’s light filters through the planet’s atmosphere Though this specific planet was known to have water before continuing on towards Earth. Different NAZARII NESHCHERENSKYI/ISTOCK/GETTY IMAGES, NASA/ESA/CSA/STSCI X 2, Þ The light curve of exoplanet WASP-96b: with its Near-Infrared Imager and Slitless Spectrograph (NIRISS), JWST took 280 individual BURADAKII/ISTOCK/GETTY IMAGES measurements of minute brightness changes to establish the planet’s transit time (2.5 hours), diameter and orbital properties 32 BBC Sky at Night Magazine September 2022

JAMES WEBB SPACE TELESCOPE SPECIAL already, JWST peered into the atmosphere of this Þ Markers for The sheer size of its primary mirror means it can alien world in more detail than ever before. measure the atmospheres of smaller planets than water among previously possible, including potentially habitable Despite not having been designed to examine the 141-point worlds in the TRAPPIST-1 planetary system. exoplanets, it’s extremely suited to the task. Previous breakdown of exoplanetary telescopes had big gaps in their data, as WASP-96b’s Here, as in all of JWST’s science aims – to see the their orbits dip in and out of Earth’s shadow. JWST, 1.5 atmosphere first stars, how worlds are formed, how galaxies evolve million kilometres from home, has no such problem. – the most exciting observations are yet to come. Interview: Hannah Wakeford One of the astronomers studying JWST’s exoplanet data tells us about the many new worlds the telescope will be exploring “Most of these planets – including to the Sun, bombarded by radiation, with Þ Many of the planets discovered by Kepler WASP-96b – aren’t going to be tourist winds blowing at thousands of miles per destinations. They are gas giants about hour. But JWST is going to give us the were between Earth and Neptune in size 20 times closer to their stars than we are ability to look at smaller worlds. anticipation for this telescope has been Over 50 per cent of planets discovered decades in the making. There’s an exciting by the Kepler Space Telescope were and terrifying amount of data to get somewhere in between the radius of Earth through, but we’re really excited to be able and Neptune (about four Earth radii). We to share it with everybody.” have nothing like that in our Solar System. Hannah Wakeford is an exoplanet JWST will look at their atmospheres to scientist and lecturer at Bristol University find out if they have hydrogen and helium, like Neptune, or if they are giant rocks with little atmosphere at all. We will also be looking at worlds in the ‘Goldilocks’ zone, where the temperature allows liquid water on the surface. We have no idea if these small rocky worlds have an atmosphere, so that’s the first question JWST is going to be able to answer. One of the key things, though, with any new telescope is to wait for the unexpected. We will be surprised. The September 2022 BBC Sky at Night Magazine 33

ADVERTORIAL ALL PICTURES: SSDA/BEN BUSH Discover the beautiful night sky in the South of Scotland The South of Scotland is the perfect choice for a stargazing break away. It’s the best of both worlds: an area with one of the lowest levels of light pollution anywhere in the UK, yet close enough to be easily accessible and perfect for a short weekend stargazing break. But you’ll want to stay longer once you discover the peace and beauty of South Scotland’s pristine night skies, and the many other attractions besides. Chief among these is Galloway Forest Park – which became the UK’s first Dark Sky Park in 2009. Here in this 775km2 haven of rolling glens and hills the sky is up to 38 times darker than urban areas, revealing a stunning display of more than 7,000 stars and planets to the naked eye – including the exhilarating sight of the Milky Way’s bright silvery band arcing overhead from horizon to horizon. OTHER UNMISSABLE HIGHLIGHTS INCLUDE • Experience dark skies with the experts at Moffat Observatory or Galloway Astronomy Centre, Whithorn, and personalised tours with Dark Sky Rangers. • Immerse yourself in the secrets of the night sky with the interactive exhibits and shows at the Dark Space Planetarium, Kirkcudbright. • Enjoy a taste of dark skies with Dark Sky Spirits in Moffat, a Dark Sky Community, or on a tour of the Dark Art Distillery in Kirkcudbright. • Relax in a hot tub beneath the starry skies at Loch Ken Eco Bothies beside Galloway Forest Dark Sky Park, or Singdean Chalet in the secluded hills of the Scottish Borders. Dark skies are closer than you think Plan your stargazing trip at www.scotlandstartshere.com/darksky

String of jewels: Mars, Jupiter Jupiter and Saturn will all be visible with the naked eye Saturn in September’s night sky Mars ARUIZHU/ISTOCK/GETTY IMAGES Prepare for the PLANET Fiveplanetsand an asteroid will be putting on a show this month. Stuart Atkinson shows us where and when to PARADE catchthespectacle September 2022 BBC Sky at Night Magazine 35

Þ Cast your eyes southeast to catch the rare sight of (left to right) Mars, Jupiter and Saturn strung across the sky and all very easy to see W hile it’s been disappointingly “With the naked eye, quiet for comet observers, September’s planet parade will aurora hunters and meteor be a celestial joy to behold” watchers, there’s no doubt CHART BY PETE LAWRENCE, MICHAEL KARRER/CCDGUIDE.COM X 2 that 2022 has been a great to show them to any space-mad youngsters, they Stuart Atkinson year for planet spotters. may need to take a nap first and then go out later. is a lifelong amateur Back in early summer there was a striking and We’ll look at the view on one particular night mid- astronomer and much-hyped ‘chain of worlds’ spread out across month, 18 September, but don’t worry if it’s cloudy author of 11 books the sky, with half a dozen planets strung out along on that night because these planets will be on view on astronomy the ecliptic like beads on a bracelet. Unfortunately, throughout September. and spaceflight that celestial treat was only visible before dawn, so many people missed it or didn’t even know it was By 10:30pm, if you look to the southeast, a happening at all. veritable parade of worlds will be stretched out before you. The brightest of them, Jupiter, will be straight But good news: another planetary parade will be ahead of you. To its right, 45˚ away, Saturn will be an on view this month! And even better news: this time it easy naked-eye object too, also appearing starlike. will be in the evening sky, so you won’t need to set the Finally for the naked-eye planets, down to Jupiter’s alarm really early to see it. Throughout September no lower left, quite some distance away (70˚ away in less than five planets – Saturn, Jupiter, Mars, Uranus fact), you’ll see Mars. and Neptune – will all be on view at once, if you look at the right time. With the naked eye, September’s planet parade will be a celestial joy to behold, but to get a closer look As exciting and rare as it was, summer’s planetary at those brighter planets, a small telescope or even a line-up wasn’t easy to see for many Northern modest pair of binoculars will make all the difference. Hemisphere sky-watchers – some of the planets Let’s take a closer look at each of the naked-eye trio were overwhelmed by the bright summer sky. But this in turn, working from right to left, then explore how month’s gathering will be taking place after dark, so to see Uranus, Neptune and Vesta. As always, it will all the planets involved will be either very easy to see help if you can get to somewhere dark, away from with the naked eye or easy to find in binoculars and the bright lights of towns and cities, and allow 20–30 small telescopes. And as an added bonus, one of the minutes for your eyes to dark-adapt. So wrap up Solar System’s most famous minor planets, Vesta, will warm, have hot drinks and snacks to hand, and get be in the same region of the sky too. ready for the planet parade. But when will be the ‘right time’? Although some of these worlds will be on view soon after sunset, you won’t be able to see all of them strewn across the sky together until around 10:30pm, so if you want 36 BBC Sky at Night Magazine September 2022

A telescope will reveal Saturn’s Titan enchanting rings, but even binoculars will bring its largest moon, Titan, into view Saturn Shining at mag. +0.4, the famous ringed Enceladus Tethys planet will rise an hour before sunset, but you won’t be able to see it clearly SATURN first view of Saturn through a telescope until twilight deepens. By 10:30pm (from – you won’t be surprised to hear that the the centre of the UK; times will vary to night, so check where it will be using a bigger the telescope you use, the better depending on your location) Saturn phone app or planetarium program. your view of Saturn will be. A 6-inch will look like a yellow-white star in reflector with high magnification will show Capricornus. If you’re worried about how Magnified more, Saturn really comes you faint banding on the planet’s disc, you’ll know which one is Saturn, don’t be: to life. Even a small telescope using low gaps in the rings and even the shadow it will be easy to identify because it will be magnification is enough to show its of the rings on Saturn itself – a view the only bright ‘star’ low in the southeast. slightly squashed disc and its rings too, as beautiful as anything sent back by looking like a slender hoop thrown over Voyager or Cassini. Having found Saturn, you’ll want to see it. As magical as this view is – and every its famous rings. They’re a sight reserved astronomer can’t help grinning like a for telescopes or the largest and most Cheshire Cat whenever they recall their powerful binoculars, but even a modest pair of binoculars will show you Saturn’s largest moon, Titan, which is as big as the planet Mercury. Through binoculars Titan looks like a star shining close to Saturn. Its position relative to Saturn changes night Pan over to find bright Europa Jupiter, where all you need are binoculars to make out JUPITER its four Galilean moons Io Ganymede Callisto Jupiter Sitting smack in the middle of the chain on when you look. The four largest moons Through a telescope Jupiter is a of worlds at 10:30pm, Jupiter will look like of Jupiter are known as the Galilean wonder. Even a small instrument will a strikingly bright blue-white star to the satellites because they were first seen by show two dark horizontal bands on its eye, 30˚ or so above the southeastern the great astronomer Galileo when he shimmering disc, and those Galilean horizon. You’ll have no trouble identifying turned his crude telescope on the night moons will look more obvious too. A it because, at mag. –2.9, there will simply sky. But as Galileo found, as they whirl large telescope magnifying at 100x will be nothing else anywhere near as bright in around Jupiter they slip in and out of view, bring subtler cloud bands into view, and the sky nearby at that time. sliding in front of the disc or vanishing Jupiter’s famous Great Red Spot – a behind it, so you might see all four or just storm larger than Earth – will be visible Through a pair of binoculars Jupiter a couple. The Jupiter’s Moons diagram in too. If you can magnify a couple of will just look like a brighter star, but you ‘The Sky Guide’ on page 49 will tell you how hundred times, you’ll see plumes and will be able to see some of its family of many moons you will be able to see, and swirls of pastel-hued clouds on its disc, 79 moons, looking like tiny stars shining which ones they are, across September. and more of its moons will be visible. > close to it. How many you see will depend September 2022 BBC Sky at Night Magazine 37

Mars The anchor at the far western end of It may lack Jupiter and Saturn’s our celestial chain of worlds is Mars. Like size, but Mars’s salmon surface Saturn and Jupiter to its right, to the and dark markings are no less naked eye Mars will look like a ‘star’ in impressive through the eyepiece Taurus. Shining at mag. –0.4 it will be obvious, but if you go out expecting the Everyone is familiar with images of Mars Saturn and a sixth as wide as Jupiter, but famously ‘red’ planet to blaze a vivid taken from orbit, showing its ochre disc you might just sneak a tantalising glimpse scarlet, you’re going to be disappointed. blotted with dark areas, but if you want of its ice cap through a smaller instrument Mars is actually more of a deep orange to see that for yourself you’ll need a large in moments when the atmosphere colour, like amber or one of the old scope, like a 6-inch+ refractor, high powers between you and Mars is calm and still. Spangles boiled sweets. and good seeing. During September, Mars’s disc will only appear half as wide as Now we’ve looked at the three naked- If you have a pair of binoculars, they are eye worlds, let’s go fainter… definitely worth training on Mars. They won’t be powerful enough to show you its disc, but they will greatly enhance its colour, making the planet appear like a gemstone in the sky. If you have the aperture for it, Faint Neptune calls for heftier see if you can pick out some scopes, especially to find Triton, of the moons orbiting Uranus’s its largest moon, shown here as green disc a dot above the planet MICHAEL KARRER/CCDGUIDE.COM, SEBASTIAN VOLTMER/CCDGUIDE.COM, ROLF LÖHR/ Uranus Neptune CCDGUIDE.COM, CHART BY PETE LAWRENCE, BERNHARD GOTTHARDT/CCDGUIDE.COM, VALERIOPARDI/ISTOCK/GETTY IMAGES, WILL TUDOR/ISTOCK/GETTY IMAGES During mid-September you’ll find Uranus roughly halfway If you’ve never managed to see Neptune with your own eyes between Mars and Jupiter. With a magnitude of +5.9 the planet before, this will be your big chance. During September it will be will technically be a naked-eye planet, but unless you know just 11˚ away from Jupiter. However, with a magnitude of just exactly which of the hundreds of 6th-magnitude points of light in +7.8, it is far too faint to see without assistance. Binoculars will that part of the sky it is, you’ll struggle to pick it out. Binoculars only show it as a faint blue-green ‘star’ lost among thousands will show Uranus as a star with a subtle greenish hue, and if you of others of equal or even greater brightness within Aquarius. If have a telescope it will resolve the planet’s small, pale green you want to be certain of seeing it, you’ll need a telescope like disc, confirming its identity. Again, a good stargazing app or a 6-inch or larger refractor, which will show you the faraway planetarium software will help you pinpoint the planet. planet’s tiny blue-green disc at high magnification. 38 BBC Sky at Night Magazine September 2022

Vesta With a diameter of around 525km, Vesta Þ You can track the motion of 4 Vesta, brightest of the asteroids, as it passes below Saturn is one of the largest known asteroids. Discovered in March 1807 by the German big a telescope you point at it, it will still a fun challenge to take several photos of astronomer Heinrich Wilhelm Matthias just look like a point of light. Its brightness its part of the sky, a week or so apart, and Olbers, it was named after Vesta, the or appearance won’t change much during look to identify which ‘dot’ to the lower virgin goddess of home and hearth from the whole of September, so you can seek left of Saturn has moved during Roman mythology. it out at any time. In fact, it might make the month. Vesta is the brightest asteroid visible from Earth, regularly visible to the naked eye as a 5th-magnitude star. This month it be will a magnitude-and-a-half fainter than that, so you’ll need a pair of binoculars to see it, and no matter how Þ Best seen with a medium-sized Þ Stunning in binoculars or a small scope, Þ The star-spangled core of the Milky telescope, the Andromeda Galaxy is the Double Cluster near the famous ‘W’ of Way, seen here from Devon in September 2021, can be a real treat in dark skies easy to find and never disappoints Cassiopeia is well worth seeking out More to explore Once you’ve taken in the planet parade, there’s a wealth of other celestial delights to see in the night sky this month When you’ve identified all the orange star at the end of the group, which is shaped a little the same binocular and small planets and explored them lower horn is the red giant like a mini Big Dipper. Other telescope field of view. with your binoculars or Aldebaran, but it’s not objects worth tracking down telescope, take a while to actually a member of the after you’ve toured the The Milky Way look at some of the other cluster, it just lies in the same planets are: The dark evenings of objects on view in the direction. Above the Hyades September are perfect for September sky. Mars will lie you’ll see a small knot of blue M31, the Andromeda Galaxy getting away from light close to two famous star stars, around the same size as Over two million lightyears pollution and enjoying the clusters. To its right you’ll see your thumbnail held out at away, this is the most distant beautiful sight of the what looks like a ‘V’ of stars arm’s length: the famous object the naked eye can see. star-frothed Milky Way lying on its side. This is the Pleiades or Seven Sisters airbrushed across the sky, Hyades star cluster, which open star cluster. Binoculars The Double Cluster with the most concentrated represents the horns of will show there are a lot more These glittering star clusters area to be found above the Taurus, the Bull. The bright than just seven stars in this sit so close together they fit in southwest horizon. September 2022 BBC Sky at Night Magazine 39

The periodic table of Charles Messier began his catalogue of observing Messier objects targets in the mid-18th century to list items Observing deep-sky objects just got a little that would distract bit easier thanks to Tom Urbain’s at-a-glance him and his assistant, guide to the targets of the Messier Catalogue Pierre Méchain, from their real aim of discovering comets. In the centuries since, the targets listed in the Messier Catalogue have undoubtedly become the most observed deep-sky objects in the night sky by amateur astronomers and astrophotographers. KEY Viewing season Messier object number Apparent magnitude GALAXIES - 40 B R NEBULAE - 10 I G OPEN H CLUSTERS - 28 T E GLOBULAR R CLUSTERS - 28 UNIQUE OBJECTS THAT DON’T FIT THE ABOVE MAIN CATEGORIES - 4 TOM URBAIN, GRAPHIC CREATOR: STARLUST.ORG, DATA SOURCE: TONY FLANDERS D EASY I M M E R VERY EASY 40 BBC Sky at Night Magazine September 2022

First published in 1781 containing visually organise them into five different group, the objects are also organised 103 objects, historical research in groups according to viewing difficulty, from brightest at the top to dimmest at the 20th century identified a further from very easy to very hard,” says the the bottom.” seven objects that were observed by UK-based astro-imager. “I based this on the French astronomers, bringing the using a mid-range telescope, such as a The graphic offers structure to the catalogue up to today’s total of 110 refractor of 8-inch aperture.” challenge of finding and observing the targets. To present this quantity of Messier objects. “It makes the ‘trial and intriguing astronomical objects in a “Each cell contains the Messier object’s error’ phase that we all go through a more understandable way, amateur number, the best viewing season and the little easier when starting out,” says astronomer Tom Urbain has transformed apparent magnitude,” he continues. “The Tom. “Beginners can therefore refrain the list into a periodic table. cells are also colour-coded depending on from trying to observe very faint Messier the object type, so it’s easy to see which objects with a 4- or 6-inch telescope and “There are quite a lot of Messier is a galaxy, a nebula, an open cluster or wondering what went wrong when they objects, so I created the infographic to a globular cluster. Within each difficulty can’t see anything.” MODERATE HARD VERY HARD September 2022 BBC Sky at Night Magazine 41



16-PAGE CENTRE PULLOUT The Sky Guide SEPTEMBER 2022 HIDDEN BY THE MOON Watch Uranus disappear from view in a lunar occultation on 14 September SHIFTING SHADOWS Track the changes in Gallilean moon shadows as Jupiter reaches opposition JUHKU/ISTOCK/GETTY IMAGES WAFER-THIN MOON Keep your eyes out for a slender morning Moon near Venus About the writers Also on view Red light friendly Get the Sky this month… Guide weekly Astronomy Steve To preserve your night expert Pete Tonkin is ✦ Magnificent Jupiter vision, this Sky Guide For weekly updates on Lawrence is a a binocular reaches opposition can be read using a red what to look out for in skilled astro observer. light under dark skies the night sky and more, imager and a Find his tour ✦ Spot what’s odd about sign up to our newsletter presenter on The Sky at of the best sights for a Harvest Moon at www.skyat Night monthly on BBC Four both eyes on page 54 nightmagazine.com ✦ Minor planet 3 Juno at opposition September 2022 BBC Sky at Night Magazine 43

SEPTEMBER HIGHLIGHTS Yourguidetothe night sky this month Thursday Saturday  1 The Moon is out of the 3 Catch the first way at the start and end quarter Moon 2.3º from the mag. +1.0 of September, making red supergiant Antares (Alpha (α) Scorpii) as the sky these perfect times to begins to darken. take this month’s Deep-Sky Tour (see page 56). Wednesday Thursday 7 Mag. –0.2 Mars 8 This evening’s lies 4.3º from 96%-lit waxing gibbous Moon lies 7º mag. +0.8 Aldebaran from mag. +0.5 Saturn. (Alpha (α) Tauri) in this morning’s sky. Both objects Minor planet 3 Juno reaches opposition, will be showing a distinctive shining at mag. +7.8 in the constellation Aquarius, 10º west orange hue. of similarly bright Neptune.  Wednesday  Friday 14 This 16 Neptune evening’s reaches 77%-lit waning opposition in gibbous Moon will Aquarius. Currently occult the planet Uranus. It located around 6º south disappears at 22:30 BST (21:30 of the Circlet asterism in UT), reappearing at 23:21 BST Pisces, the planet shines (22:21 UT). Times will vary at mag. +7.8. slightly with location. Turn to page 46 for more. Friday Saturday Sunday 23 The Sun crosses the celestial equator 24 Io and its 25 From heading south at 02:04 BST (01:04 UT), shadow 06:30 marking the September equinox, also transit Jupiter this BST (05:30 UT) known as the Northern Hemisphere’s morning from 02:57 there’s an autumn equinox and the Southern Hemisphere’s BST (01:57 UT) until 05:12 BST excellent chance to spot an spring equinox. (04:12 UT). As the planet is ultra-thin 0.6%-lit waning near opposition, the moon crescent Moon just 2º north This morning’s 7%-lit waning crescent and its shadow will appear of mag. –3.8 Venus. Turn to Moon passes just south of mag. +3.5 very close together. page 47 for more. Eta (η) Leonis. From the centre of the UK at 04:00 BST (03:00 UT) the northern cusp of the Wednesday  Moon is just 8 arcseconds south of the star. 28 The giant PETE LAWRENCE X 9 moon Ganymede, along with its shadow, transit Jupiter from 05:06 BST (04:06 UT), the event still in progress as Jupiter sets. 44 BBC Sky at Night Magazine September 2022

Monday NEED TO 5 This evening, a view of the Moon through KNOW binoculars or a small telescope will show the dawn-lit peaks of the Jura Mountain range arcing across The terms and symbols the lunar terminator. This forms a clair-obscur effect used in The Sky Guide known as the Jewelled Handle. Universal Time (UT) A view of Jupiter from 00:30 BST (23:29 UT on 4 September) and British Summer through to 01:47 BST (00:47 UT) will show Callisto’s shadow just Time (BST) clipping the planet’s south polar region. Universal Time (UT) is Saturday  Sunday the standard time used by astronomers around 10 The 11 Just after the world. British Moon is rising this Summer Time (BST) is full at 10:59 BST evening, the 97%-lit one hour ahead of UT (09:59 UT) but waning gibbous Moon won’t be visible until later in lies 3.8º to the east of mag. RA (Right ascension) the day. This full Moon is –2.8 Jupiter. and dec. (declination) closest to the September equinox, making it the These coordinates are the Harvest Moon for 2022. night sky’s equivalent of longitude and latitude, Saturday Thursday  describing where an object is on the celestial ‘globe’ 17 The 22 This 58%-lit morning Family friendly waning gibbous is the second of two Moon sits 2.9º opportunities to Objects marked north of mag. –0.4 Mars this catch our Moonwatch target, with this icon are perfect morning. Catch them the walled plain Schickard. for showing to children together after 01:00 BST The first is on the evening of (00:00 UT). 8 September. See page 52. Naked eye Friday  Monday Allow 20 minutes for your eyes to become 30 The 26 The dark-adapted 25%-lit planet waning crescent Jupiter reaches Photo opp Moon this evening opposition today, sits 2.3º from mag. +1.0 shining at mag. –2.8 in Pisces. Use a CCD, planetary Antares (Alpha (α) Scorpii), camera or standard DSLR the pair visible low above the Catch an ultra-thin southwest horizon shortly waxing crescent Binoculars after the Sun has set. Moon shortly after sunset. Turn to page 47. 10x50 recommended Family stargazing Small/ medium scope The full Moon on 10 September is the Harvest Moon for 2022, so-called because the difference in rise times from Reflector/SCT under 6 inches, one evening to the next after this date is the smallest for refractor under 4 inches the year. This means the bright, fuller phases of the Moon appear at approximately similar times, lighting the way to collect the Large scope harvest. Young scientists might like to make a note of the rise times for the Moon from 10 September onwards (find them at Reflector/SCT over 6 www.timeanddate.com/moon) and calculate the difference. inches, refractor over 4 inches Try to remember to do this next March too, when the difference is greatest. bbc.co.uk/cbeebies/shows/stargazing GETTING STARTED 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 September 2022 BBC Sky at Night Magazine 45

THE BIG THREE The top sights to observe or image this month DON’T MISS Lunar occultation of Uranus BEST TIME TO SEE: 14 September, 21:30 BST (20:30 UT) until 23:30 BST (22:30 UT) Disappearance Reappearance 22:30 BST (21:31 UT) 23:21 BST (22:21 UT) Altitude 11° Altitude 19° Þ It will take around eight seconds for Uranus to disappear behind the Moon’s leading, bright limb as occultation begins Moon’s phase: 14 September: times Þ After disappearing for 50 minutes, its 77%-lit waning correct for the centre of UK and will vary slightly return from behind the Moon’s following, dark limb will also take eight seconds depending on location ALL PICTURES: PETE LAWRENCE The Moon will appear to pass in nearby, so identifying Uranus shouldn’t be dark western edge (eastern limb). The front of the planet Uranus on too hard. Once you’ve located it, there’s period of time Uranus is hidden will also 14 September, an event known as a lunar nothing more to do than wait. vary slightly with location, so observe the occultation. Lunar occultations of faint Moon’s dark edge earlier than the stars are common, but seeing the Moon The Moon’s bright limb slowly expected reappearance, say from 23:10 move in front of a bright star is relatively approaches Uranus until first contact, the BST (22:10 UT). Again, Uranus should take infrequent. Seeing the Moon pass in front time of which varies slightly with location. around eight seconds to be fully revealed of a planet is quite a rare event. It’s recommended to keep watching the as the Moon moves east. On 14 September, the Moon will be at planet when the Moon is close. From the 77%-lit waning gibbous phase. Uranus, centre of the UK, Uranus will make A telescope setup showing the entire shining at mag. +5.7 will require binoculars contact with the Moon’s eastern edge Moon’s disc guarantees a view of the or a telescope to see properly. Locate the (western limb) at 22:30 BST (21:30 UT). reappearance, although it’ll be hard to see planet at 21:30 BST (20:30 UT) and Uranus as anything more than a dot. More familiarise yourself with where Uranus is Uranus has an apparent diameter of magnification will show the planet as a positioned relative to the Moon’s disc. At 3.7 arcseconds and will take around eight disc, but this increases the possibility of this time, the separation between Uranus seconds to fully disappear. Atmospheric missing the reappearance. If you have an and the eastern edge of the Moon seeing will have a big effect here, the tiny accurate, polar-aligned mount, centring (confusingly, the Moon’s western limb) will planetary disc being heavily influenced by on Uranus at high magnification and be around one apparent lunar diameter. Earth’s unstable atmosphere. sticking with it as the Moon performs the There’s nothing else of a similar brightness occultation is the best way to guarantee a Uranus remains hidden for around 50 high-powered view. minutes, the planet reappearing at 23:21 BST (22:21 UT) from behind the Moon’s 46 BBC Sky at Night Magazine September 2022

Thin Moon spotting with Venus BEST TIME TO SEE: 25 September, from 40 minutes before sunrise (stop viewing at sunrise) When the Moon is presented Try to spot the ultra-thin Moon CAUTION against a truly dark sky, it’s easy to in the east before sunrise on locate as it dominates the view. When it’s 25 September. Moon’s size Only attempt to in the daytime sky, it’s less easy to see exaggerated for clarity find Venus and the due to lower contrast, but the thicker phases can still stand out pretty well. 2o Moon when the When the Moon appears in the daytime Sun is below sky or twilight periods with a phase less But best of all, if you go looking for this the horizon than 2% it becomes significantly trickier particular Moon, you’ll have a guide in the to pick out. When it’s presented with a form of the brilliant planet Venus. If you Moon phase less than 1% it’s downright difficult! have a clear view looking towards the This will be the case on the morning of eastern horizon on the morning of 25 Venus 25 September: a 0.6%-lit waning crescent September, point your binoculars at Venus Moon situated 8˚ from the Sun. This is an and in the same field of view, just to the left and up a bit from the planet, there will interesting arrangement for several be that ultra-thin lunar crescent. If you reasons. The ecliptic makes a steep angle look but can’t see it, look again removing with the eastern horizon at this time of all preconceptions of how you think the year before sunrise. This means that the crescent should look. It will be extremely Moon, which never moves that far from delicate and very tricky to see. Be sure to the ecliptic, will be optimally placed above stop looking before the Sun rises. the horizon before sunrise. In addition, there’s a theoretical limit as to how far a Moon can be from the Sun before it becomes invisible. This value is known as the Danjon limit and is usually quoted as about 7˚. The morning Moon on 25 September is perilously close to this value, with an actual separation value of 7.9˚ from the Sun. Harvest Moon 2022 BEST TIME TO SEE: Moonrise on 8–12 September and 7–11 October The Moon is full at 11:00 BST It’s an interesting exercise to note the calculating the differences. Waiting for (10:00 UT) on 10 September, rise time of the Moon on 8 September, the fuller phases of the Moon to rise is a the closest full Moon to the Northern then again on 9, 10, 11 and 12 September, great way to experience the visual effect Hemisphere’s autumn equinox, which is at 02:03 BST (01:03 UT) on Track the unusually similar of the Moon illusion, which makes 23 September. This makes it the moonrise times either side these phases appear enormous Harvest Moon for 2022. of the Harvest Moon when close to the horizon. The full A Harvest Moon’s proximity to Moon on 9 October is just a couple the September equinox means that of days further away from the the rise times for the near-to-full equinox than September’s and phases of the Moon are nearly the you’ll observe a similar pattern in same on the days before and after the rise times for its fuller phases. 10 September. It was the abundance of bright early-evening The period close to the March moonlight on those consecutive equinox represents the opposite days that traditionally lit the fields situation, with the difference for collecting the harvest. between successive moonrises for the fuller phases of the Moon being the largest of the year. September 2022 BBC Sky at Night Magazine 47

THE PLANETS Our celestial neighbourhood in September PICK OF THE PISCES A bright Jupiter sits near the Circlet and the First Point of Aries as it nears opposition MONTH εδ θ Circlet ι β Jupiter Ecliptic γ λ κ Equator 1 Sep Best time to see: 26 September, 00:00 UT Equator Jupiter 30 Sep 1 Sep Altitude: 37˚ Location: Pisces 30 Sep Ecliptic Direction: South φ Neptune Features: Detail of the planet’s χ atmosphere, Galilean moons Recommended equipment: ψ2 ψ1 75mm or larger CETUS ψ3 ι AQUARIUS θ Jupiter will reach opposition on 26 η September and, when viewed through the eyepiece, appears brightest and largest a peak altitude of 37˚ as seen reveal the four largest and for this period of observation. Reaching an impressive mag. –2.8, it slips from from the centre of the UK. brightest Jovian moons, Cetus into Pisces throughout September, the planet located east of the faint but Jupiter rotates quickly, the so-called Galilean distinctive Circlet asterism. the planet completing moons: Io, Europa, A bright full Moon lies near to Jupiter on the nights of 10 and 11 September, an one rotation in under Ganymede and Callisto. impressive sight if you have clear skies. As they rise above the eastern horizon early 10 hours. This brings The inner three can evening on 11 September, Jupiter and the Moon will appear a little over 3˚ apart. atmospheric features appear to pass in front On opposition night, it sits 4˚ east of the into and out of view of and behind the planet, First Point of Aries, one of two intersections in the sky where the celestial equator surprisingly quickly. A but Jupiter’s apparent and the ecliptic cross. The First Point of Aries marks the start of the RA coordinate 100mm or larger telescope tilt from Earth has now system (00h00m00s). Jupiter shines at mag. –2.8 on opposition night, reaching will show the planet’s increased such that Callisto famous Great Red Spot, Þ Larger instruments appears to miss the disc, the appearance of which will reveal the planet’s although its shadow can still can be determined using swirling atmosphere clip Jupiter’s southern pole. PETE LAWRENCE X 2 the freeware WinJupos This phenomenon can be application (jupos.org/gh/download.htm). observed on 5 September between 00:30 In addition to the planet’s detailed BST (23:30 UT on 4 September) and 01:47 atmosphere, a small telescope will also BST (00:47 UT). The planets in September The phase and relative sizes of the planets this month. Each planet is shown with south at the top, to show its orientation through a telescope Venus Mars Jupiter Saturn Uranus Neptune 15 Sep 15 Sep 15 Sep 15 Sep 15 Sep 15 Sep Mercury 1 Sep Mercury 15 Sep Mercury 30 Sep 0 10 20 30 40 50 60 ARCSECONDS 48 BBC Sky at Night Magazine September 2022

Mercury 3˚ north of Mars on the JUPITER’S MOONS: SEP morning of 17 September. Best time to see: Using a small scope you can spot Jupiter’s biggest moons. Their 30 September, 30 minutes Saturn positions change dramatically over the month, as shown on the before sunrise diagram. The line by each date represents 01:00 BST (00:00 UT). Altitude: 5˚ (low) Best time to see: Location: Virgo 1 September, 23:00 UT DATE WEST EAST Direction: East Altitude: 21˚ Mercury’s position in the Location: Capricornus 1 evening sky is poor at the start Direction: South 2 of September, appearing dim Following opposition on 3 and setting shortly after 14 August, Saturn remains well 4 sunset. Inferior conjunction is placed all month, dropping in 5 on 23 September. Mercury then brightness only slightly from 6 reemerges into the morning mag. +0.4 on 1 September to 7 sky where it becomes easier to +0.6 by the end of the month. 8 see. By the end of the month, it A bright waxing gibbous Moon 9 shines at mag. +1.8 and rises 70 sits nearby on the nights of 7/8 10 minutes before the Sun. and 8/9 September. 11 12 Venus Uranus 13 14 Best time to see: 1 September, Best time to see: 15 30 minutes before sunrise 30 September, 02:30 UT 16 Altitude: 7˚ (low) Altitude: 54˚ 17 Location: Leo Location: Aries 18 Direction: East-northeast Direction: South 19 Shining at mag. –3.8 on Morning planet Uranus is 20 1 September, Venus can be perfectly placed for UK 21 seen rising above the east- observation, able to reach an 22 northeast horizon 90 minutes altitude of around 50˚ under 23 before the Sun. Telescopically, dark skies. Visible as a 24 it isn’t well presented, at 10 green-hued mag. +5.7 disc 25 arcseconds across and nearly through the eyepiece, a rare 26 fully illuminated. By the end of lunar occultation of Uranus 27 the month, Venus’s position takes place on the evening of 28 degrades further and it 14 September. See page 46. 29 becomes harder to see, rising 30 40 minutes before sunrise. Neptune 1 Mars Best time to see: 8 76 54 3 2 1 01 2 34 5 6 78 16 September, 00:15 UT arcminutes Best time to see: Altitude: 34º 30 September, 04:50 UT Location: Aquarius Jupiter Io Europa Ganymede Callisto Altitude: 59˚ Direction: South Location: Taurus Neptune reaches opposition Direction: South on 16 September, but at its Mars shows dramatic changes great distance from Earth this as it approaches opposition on usually favourable position has 8 December. On 1 September, very little effect on the shining at mag. –0.1, it is planet’s visual appearance. located just north of the Able to reach an altitude Hyades. Through a telescope around 30˚ under dark sky the planet is 9 arcseconds conditions all month long, across on 1 September, you’ll need at least binoculars increasing to 11 arcseconds to spot mag. +7.8 Neptune. and mag. –0.6, a beacon between the horns of Taurus, More ONLINE by the month’s end. A 58%-lit waning gibbous Moon lies Print out observing forms for recording planetary events September 2022 BBC Sky at Night Magazine 49

THE NIGHT SKY – SEPTEMBER Explore the celestial sphere with our Northern Hemisphere all-sky chart NORT KEY TO When to use this chart HEAST STAR CHARTS 1 September at 01:00 BST Arcturus STAR NAME 15 September at 00:00 BST 30 September at 23:00 BST PERSEUS CONSTELLATION AURIGA α NAME On other dates, stars will be in slightly different positions β GALAXY because of Earth’s orbital motion. Stars that cross the M37 AlphPaeAaukri1gSidespt sky will set in the west four minutes earlier each night. M35 M38M36 OPEN CLUSTER GLOBULAR How to use this chart UV Capella CLUSTER Kids 1. Hold the chart β TAURUS PLANETARY so the direction 30th NEBULA you’re facing is at the bottom. DIFFUSE Mars α α NEBULOSITY 2. The lower half of the chart Aldebaran δ DOUBLE STAR shows the sky PERSEUS VARIABLE STAR ahead of you. Algol THE MOON, 3. The centre of 1st Pleiades Mβ SHOWING PHASE the chart is the point directly δ Hyades TRIANGULUM over your head. γ APlepahka1T1/ri1a2nSgeuplitds COMET TRACK M45 Hamal Sunrise/sunset in September* EAST 15th P 12th ASTEROID Date Sunrise Sunset Uranus βα CETUS TRACK γ 1 Sep 2022 06:19 BST 20:00 BST Deneb Kaitos STAR-HOPPING 11 Sep 2022 06:36 BST 19:36 BST α PATH 21 Sep 2022 06:54 BST 19:11 BST ARIES 1 Oct 2022 07:11 BST 18:47 BST METEOR RADIANT Moonrise in September* Circlet ASTERISM Moonrise times γ β α Menkar γ 1 Sep 2022, 12:21 BST 17 Sep 2022, 22:10 BST Ecliptic 5 Sep 2022, 17:48 BST 21 Sep 2022, --:-- BST PLANET 9 Sep 2022, 19:55 BST 25 Sep 2022, 06:05 BST δ 13 Sep 2022, 20:42 BST 29 Sep 2022, 11:34 BST QUASAR α *Times correct for the centre of the UK Mira ο T STAR BRIGHTNESS: Lunar phases in September MAG. 0 Monday Tuesday Wednesday Thursday Friday Saturday Sunday & BRIGHTER 12 34 MAG. +1 5¼ N MAG. +2 5 6 7 8 9 10 11 SOUTHEAS E MAG. +3 MAG. +4 FULL MOON & FAINTER 12 13 14 15 16 17 18 W COMPASS AND CHART: PETE LAWRENCE FIELD OF VIEW S 19 20 21 22 23 24 25 MILKY WAY NEW MOON 26 27 28 29 30 50 BBC Sky at Night Magazine September 2022