Indholdsfortegnelse for October 2024 i BBC Sky at Night

EYE ON THE SKY VICTOR M BLANCO 4-METER TELESCOPE, 14 AUGUST 2024 Captured using the Dark Energy Camera (DECam) on NOIRLab's Victor M Blanco 4-Meter Telescope in Chile, this image shows the Coma Cluster – a group of over 1,000 galaxies that lies 321 million lightyears from Earth in the constellation of Coma Berenices. To the right of centre are the large galaxies NGC 4874 and NGC 4889 which, like most in the cluster, are elliptical. It was after observing the anomalous movement of galaxies within this cluster that astronomer Fritz Zwicky concluded in 1933 that it must contain an enormous quantity of an unseen substance – a ‘dark matter’ that stopped the rapidly moving galaxies flying apart. FREE BONUS CONTENT Explore a gallery of these and more stunning space…

Some novel observations may have solved the mystery of why the expansion rate of the Universe appears to change depending on how you measure it. Astronomers assess the Universe's expansion in two ways: by looking at radiation from the Big Bang, which gives a value of 67.4km per second per megaparsec; or from the motion of nearby galaxies, which gives 74km per second per megaparsec. It's unclear if the disagreement is because our assumptions about the Universe are wrong, or if it's our measurements of galactic distances. Many astronomers believe the latter is the culprit. These measurements are made using standard candles, objects with a known intrinsic brightness. By comparing how bright they are with how they appear, we can determine their distance. To calibrate a ‘distance ladder’, we need…

The Moon's tenuous atmosphere is created by meteorite impacts, according to the latest study using Apollo rock samples. In the 1980s, astronomers discovered the Moon hosts a very thin atmosphere known as the exosphere. Given how much of the exosphere escapes, something must be continuously replenishing the atoms from which it's made. It's thought that the gas is liberated from surface rocks, either through ion sputtering, where the solar wind bombards the soil, releasing atoms into the exosphere, or through continuous bombardment by micrometeorites, a process known as impact vaporisation. Orbital studies by the Lunar Atmosphere and Dust Environment Explorer (LADEE) found that during meteor showers the number of atoms in the exosphere increased. But it also found that the number changed during an eclipse, when the Moon was shielded…

PARTICLE PHYSICS 101 According to the successful standard model of particle physics, everything in the material Universe – galaxies, stars, planets and people – consists of protons, neutrons and electrons. In addition, elusive neutrinos that hardly interact with other particles zap through space at near-lightspeed. Using powerful particle accelerators, physicists have also studied antimatter and other short-lived particles. But if you think they've figured it all out by now, you'd be wrong. One type of particle has escaped detection so far. Known as dark matter, it accounts for 85 per cent of the total mass of the Universe. Back in the early 1930s, astronomer Fritz Zwicky studied the motions of galaxies in the Coma Cluster (pictured on page 6). He realised that if the visible stars and gas were the…

The DART mission proved that this method of deflecting an asteroid works. It's Hera's mission to turn the experiment into a controllable, repeatable planetary defence strategy. The first step is to identify an asteroid threat. ESA is currently developing an early-warning system using up to four ‘Flyeye’ telescopes that will scan the sky each night, while NASA is planning to launch the NEO Surveyor mission in 2027. This infrared telescope is expected to discover up to 300,000 new near-Earth objects (NEOs), which include asteroids as well as comets and meteors. In July 2024, ESA announced its Rapid Apophis Mission for Space Safety (Ramses). This will accompany asteroid Apophis during its close fly-by of Earth in 2029, to study how the tidal forces of Earth's gravity stretch and squeeze the asteroid.…

W hile many modern mounts have Go-To navigation, beginners often start off with a telescope setup that includes a manual (nonGo-To) equatorial mount. Most manual equatorial mounts come with a dial on their RA and dec. axes, which together are known as setting circles. These can be used to accurately point your scope even when the target can't be seen in a finderscope. They can also help to locate a bright object – such as a planet – in the daytime sky. So knowing how to use setting circles to point your telescope at objects is particularly useful. Celestial objects are located by using the coordinates of right ascension (RA) and declination (dec.), the celestial sphere's equivalent of longitude and latitude on Earth's surface. Right ascension is measured eastwards from…

STEP 1 A low-altitude comet presents many issues, with added jeopardy from the Moon. Being diffuse, both natural and artificial light pollution will make the comet harder to see. For views from 11 October on, under daylight conditions find somewhere with a flat, low and clear west to west-southwest horizon. STEP 2 For early shots (11–17 October), we recommend a wide to mid-angle setup. Make frequent adjustments for twilight. For navigation, use bright star Arcturus, then identify Gemma in Corona Borealis. Spin the Arcturus–Gemma line 90° counter-clockwise; the free end points roughly where the comet will be mid-month. STEP 3 If you have a smartphone with a night shooting mode, select it, make sure that focus is good and take the exposure. Some phones offer longer exposure times if the…

VITAL STATS • Price £589 (visual and astrophotography bundle) • Optics ED doublet, FPL53 low-index fluoro-crown glass • Aperture 70mm • Focal length 420mm, f/6 • Focuser Dual-speed, 1:10 ratio • Extras Mounting ring, dovetail base, red dot finder, 1.25-inch dielectric diagonal, 17mm eyepiece, push-fit adaptor, 0.8x focal reducer, Allen keys, carry case • Weight 2kg; 4kg with accessories • Supplier Altair Astro Ltd • Tel 01603 721946 • www.altairastro.com Small refractors are great multi-purpose instruments that don't require collimating, but budget models often suffer from chromatic aberration that affects our visual and imaging experience. Altair's Starwave Ascent 70ED compact refractor now features improved optics to mitigate this, so we were looking forward to trying it out. We received the full visual and astrophotography bundle, which comprises of the Starwave…

What did your study involve and what did you discover? We studied the data acquired by the radar of NASA's Lunar Reconnaissance Orbiter in 2010 and discovered the entrance to a subsurface cave right at the bottom of the Moon's Sea of Tranquillity. By developing a technique for better signal processing, we could squeeze more from the data, seeing it from a different perspective. We showed that we have a cave accessible from the lunar surface with a diameter of at least 45 metres, and estimated that we could enter the cave to a depth of between 30 and 70 metres. Our technique doesn't show whether the cave continues after those 70 metres, so this is still an open question. What signs were there that it could be a cave?…

BULLETIN Liquid water has been found on Mars. The underground reservoirs could provide a potential habitat for Martian life, but unfortunately we'll probably never know as the water is located up to 20km (13 miles) below the surface. The presence of river channels, deltas and wateraltered rocks on Mars mean it's now widely believed that water flowed across Mars until around three billion years ago. The big mystery, however, is where that water went. Though some evaporated into space, this can't explain all the water loss. Geologists had suspected the rest may have gone underground, potentially creating habitable havens where Martian life has been able to thrive. “Understanding the Martian water cycle is critical for understanding the evolution of the climate, surface and interior,” says Vashan Wright, from the University…

Astronomers think they know when to next ring a black hole's dinner bell, after they accurately predicted when the supermassive giant would snack on a nearby star. The black hole, which is 50 million times the mass of our Sun and located in a galaxy about 860 million lightyears from Earth, first became of interest when it suddenly brightened in 2018. Follow-up observations determined the surge was due to a tidal disruption event, when a passing star is torn apart and consumed by a black hole. The gas is heated as it's pulled in, releasing more X-ray and ultraviolet radiation which then suddenly falls away when the gas is consumed by the black hole. When this happened after the 2018 event, astronomers assumed the star had been swallowed whole. Then…

ESA's Gaia spacecraft suffered a double whammy of bad luck after being hit by a micrometeorite and then a solar storm. Since December 2013, the spacecraft has monitored the positions of over a billion stars. Knowing Gaia would be struck by many micrometeorites – tiny dust particles travelling at extremely high velocity – it was built with a protective shield. But last April, a particle smaller than a grain of sand struck at just the wrong angle, damaging the shield and letting through a tiny amount of light. While the team were dealing with that issue, Gaia was caught in the largest solar storm in 20 years. The storm's radiation is believed to have damaged a sensor that the space observatory uses to confirm which stars are real. “Gaia typically…

You joined the astronaut reserve last year. What have you been up to since then? I officially started with the European Space Agency in June 2023 to begin the Fly! Feasibility Study, which is looking at the requirements for someone like myself [a lower-limb amputee] to fly on a long-duration mission to space. We're investigating how my disability and my prosthesis might impact the requirements to fly in space, how we make up any differences and what alterations or mitigations might be needed. How do you go about assessing what those requirements might be? We looked at all the different stages of spaceflight. We investigated what would be required for an astronaut to undertake basic training, things like winter and sea survival training, centrifuge familiarisation and experiencing low-pressure environments. Can…

From the International Space Station, the wonderous sight of Earth's land masses and seas passing below would surely never become tiresome. But it seems that astronauts on prolonged tours of duty in space have found other activities to be a necessary stimulus, and they've tried all manner of leisure pursuits beyond simply watching the world go by. In a sporting context, golf features high up on the activity list. At the risk of having a good spacewalk ruined, the first to set a trend and tee off was Apollo 14 astronaut Alan Shepard. During a live broadcast from the Moon in February 1971, he decided to share his skills by attempting to drive a ball down the lunar fairway with a six iron. Whereas Earth-based golfers might be able to…

Half a billion miles (800 million kilometres) from Earth, radiation-drenched and dimly lit by the feeble glow of the distant Sun, lies a shimmering waterworld. This is the destination NASA's Europa Clipper mission plans to set off to explore in October. Its decade-long voyage may reveal that a happy coincidence of conditions needed for life – water, organics and energy – somehow fell into place on a world beyond our own. Circling giant Jupiter at a distance of 671,000km (417,000 miles), Europa is an enigmatic moon, smaller in diameter than Australia is wide. Its surface rhythmically flexes under its parent planet's colossal gravity and is washed by the intense Jovian magnetic field, 20,000 times fiercer than Earth's. Nine tenths as big as the Moon yet five times further from the…

Sinus Viscositatis Type: Lunar bay Size: 68km x 50km Longitude/latitude: 41° W, 35.2° N Age: Around 3.9 billion years Best time to see: Three days after first quarter (13 and 14 October) or two days after last quarter (27 and 28 October) Minimum equipment: 100mm telescope Chances are you may not have heard of the wonderfully named Sinus Viscositatis, the Bay of Stickiness, its name only being officially sanctioned by the International Astronomical Union on 30 December 2022. Sinus (from the Latin for bay) is not a strictly geological term and in the context of the Moon it refers to features that are basically small plains. Possibly the bay that we're most familiar with is the semicircular feature on the northwestern shore of 1,250km Mare Imbrium, namely 400km x 260km…

1. Psi1 Piscium 10x50 You'll find Psi1 (ψ1 )Piscium in the northern ‘branch’ of the Pisces asterism, 1.5° from mag. +4.7 Chi (χ) Piscium in the direction of mag. +4.4 Eta (η) Andromedae. This is a delightful double of two brilliant-white stars (mag. +5.33 and +5.55), separated by 30 arcseconds. If you find it difficult, mount the binoculars, make sure that your focus is perfect and put the object exactly in the centre of the field of view. SEEN IT 2. 14 Arietis 15x70 The triple star 14 Arietis is 2.5° N of mag. +2.0 Hamal (Alpha (α) Arietis). The brighter two members (mag. +4.98 and +7.92) are easy and separated by 105 arcseconds. The mag. +11.33 third member is considerably fainter and is 12 arcseconds closer to the primary.…

As skywatchers and amateur astronomers all around the world wait anxiously to see if comet C/2023 A3 (Tsuchinshan– ATLAS) lives up to its early promise of becoming a bright naked-eye comet in the October evening sky, now seems like a good time to take a look at what comets are, where they come from and why comets like A3 are so fascinating to astronomers. Comets are among the smallest members of our Sun's family and there are lots of them out there – so many, in fact, that if you set your favourite astronomy app to ‘Show all comets’, your screen will fill up with so many dots you won't be able to see the stars! People used to be very afraid of comets. They thought they were terrifying cosmic…

Step 1 Start with your scope in parked position, facing north with the finderscope aligned. Set the altitude to that of Polaris (+52 in the UK). Align on it (follow your mount's instruction manual). Mounts with built-in polarscopes can get an accurate polar alignment. Step 3 Using an up-to-date catalogue or planetarium program, look up the RA and dec. positions of the reference and chosen targets. Note: setting circles don't provide accuracy right down to the second (RA) or arcsecond (dec.); minutes and degrees will do. Step 5 Lock both setting circles to stop them rotating. Release the mount clutches and move the scope so the setting circles match the RA and dec. position of the target. If using a non-tracking mount, time is critical for RA, so this needs…

ALL PICTURES: MARTINA MCGOVERN Comets are faint objects that move faster than our background stars. When a comet passes a deep-sky object, long-exposure astro photos can produce fantastic results. But when you're imaging a comet, increasing the image brightness by stacking aligned on the stars won't work; the comet just becomes blurred. Stacking aligned on the comet doesn't work either; that causes the stars to trail. This month and next, I'll explain how to create an image with a sharp comet and stars, using my photo of comet C/2017 K2 Pan-STARRS passing globular cluster M10 in July 2022 (above) to explain the composite techniques behind it. I used DeepSkyStacker, PixInsight and Photoshop to stack, process and blend two images: one of the stars and M10, and one of the comet.…

BULLETIN An ‘eccentric’ exoplanet has been found to have one of the most stretched-out orbits of any planet ever seen. It's thought the extreme orbit is the beginning stage of the planet's journey towards becoming a ‘hot Jupiter’, and could give new insight into how these planets form. Hot Jupiters are gas giants much like our own Jupiter, but which orbit incredibly close to their stars. Our current understanding of planet formation suggests it's far too hot for planets to form in that location. Instead, the leading theory is that these worlds were born in more distant orbits and then migrated inwards at a later date. If this is the case, then it should be possible to detect exoplanets while they are undergoing this migration. One potential example is TIC…

Our experts examine the hottest new research CUTTING EDGE Over its planetary history, Mars has suffered an environmental collapse. During its early era, over 3.6 billion years ago, there was clearly a lot of liquid water moulding its landscape, carving out deep canyons and filling large lakes. Today, however, the Red Planet is a freeze-dried desert. In general, water in its liquid state is simply not stable on the planet's surface and exists only as ice near the poles or as wispy vapour in the thin atmosphere. This transformation from a wetter world to an arid planet occurred during a period known as the Hesperian and is recorded in the landscape by water-formed features that become increasingly few and far between. The details of this climate catastrophe, including the exact…

Once again, photographers from around the globe have submitted their best images as they vie for the title of Astronomy Photographer of the Year 2024. Over 700 individuals submitted a total of 3,741 entries, from which the judges have selected the very best. There are eight categories, as well as two special prizes for the best newcomer and for the most creative processing of data from professional observatories, and a separate competition for entrants under 16. You can see all of the winning photos for yourself at the National Maritime Museum in Greenwich, London from Friday 13 September. For details, visit www.rmg.co.uk/astrophoto. OVERALL WINNER / Our Sun Distorted Shadows of the Moon's Surface Location: Odessa, Texas, USA Equipment: Nikon D810 camera, iOptron SkyGuider Pro mount, Sigma 150-600mm f/5-6.3 DG OS…

DON'T MISS Comet C/2023 A3 Tsuchinshan –ATLAS BEST TIME TO SEE: Mid-October onwards, from around 20:00 BST (19:00 UT) Comet C/2023 A3 Tsuchinshan– ATLAS takes centre stage this month. A much-anticipated object, C/2023 A3 is predicted to be above naked-eye brightness during October. After swinging rapidly through its closest approach to the Sun (perihelion) in late September, this month we get to see the aftermath of its solar encounter. Perihelion occurred on 27 September, when C/2023 A3 passed 58.6 million kilometres from the Sun, a similar distance as Mercury's orbit. This was the comet's first close encounter with our star, having travelled to the inner Solar System from the Oort cloud, a theorised outer region 2,000–200,000 AU (0.03–3.2 lightyears) from the Sun. It's thought the Oort cloud contains trillions of…

PICK OF THE MONTH Neptune Best time to see: 1 October, around midnight Altitude: 35° Location: Pisces Direction: South Features: Colour, Triton, subtle banding through larger instruments Recommended equipment: 200mm scope or larger Neptune is the Solar System's most distant planet and one that poses a bit of a challenge for amateur kit. Taking 165 years to travel once around its orbit, Neptune is not a fast mover against the background stars. It's currently located in a barren batch of sky just southeast of the faint Circlet asterism in Pisces. As a rough guide, it's currently approximately mid-way between mag. +4.5 Lambda (λ) Piscium and mag. +4.3 30 Piscium. Neptune tracks from a position 1.7° east-northeast of mag. +5.5 20 Piscium on 1 October to end the month 1° eastnortheast…

Minor planet 20 Massalia shines at mag. +9.3 on 1 October, dimming to +10.1 by the end of the month, placing it well within reach of a small telescope. Finding it will be more of a challenge. The object is located in Pisces, east of the Circlet asterism. Saturn lies nearby in Aquarius, 14° southwest of the Circlet's centre, but dim Neptune is the better navigational aid – assuming you can find it, of course! To locate Neptune and Massalia, you will need to star-hop through some sixth- and seventh-magnitude stars to the east and southeast of the Circlet. At the start of October, the key star is mag. +5.8 44 Piscium, a double star in Pisces. On the morning of 1 October, Massalia is located just shy of 1.2°…

This month, we invite you to try to record a lunar occultation of a star. This isn't particularly hard, simply requiring you to catch the Moon moving in front of a star, something that doesn't occur as often as you might think. There are plenty of occultations on 19 October (see page 47), when the Moon passes in front of the southern Pleiades, but for other events you'll need to fire up your favourite planetarium app and see whether any occultations loom from your viewing site. A driven telescope opens up a world of occultation possibilities and in theory all you need to do is locate the star before it disappears behind the Moon's leading edge and keep watching it. Pretty simple, right? Well, in many ways it isn't. The…

On 26 September 2022, 11 million kilometres (7 million miles) from Earth, a spacecraft weighing 610kg (1,345lb) hurtled through space at 6.1km per second (13,645mph) and crashed headlong into an asteroid called Dimorphos. The plume of debris it sent up was like something from a science-fiction disaster movie, but it was far from that. This was the culmination of NASA's Double Asteroid Redirection Test (DART), a mission designed to test Earth's ability to deflect an asteroid using a kinetic impactor. The collision shortened the orbit of Dimorphos, demonstrating for the first time that humanity can alter the orbit of a body in space and defend our planet from incoming asteroids. This month, the European Space Agency (ESA) plans to launch a followup mission to study the impact of this collision.…

This is the month when we may or may not see comet C/2023 A3 Tsuchinshan–ATLAS, depending on whether it survives perihelion on 27 September, when it passes within 58.6 million kilometres of the Sun. Assuming it survives, it should become visible after 11 October, an evening comet visible in darkening twilight. Here we'll take a look at the best ways to photograph it. If C/2023 A3 performs as predicted, its coma and adjacent tail stub should become visible as twilight darkens, but its full glory won't be realised until true darkness falls. Of course, as is often the case with comets, near the peak of C/2023 A3’s brightness, as we wait for true darkness the comet will lose what little altitude it has and consequently the view won't improve much.…

FREE BONUS CONTENT Find our extended Gallery at www.skyatnightmagazine.com/ bonus-content Corona Australis molecular complex Vikas Chander, captured remotely via Deep Sky Chile, 7–11 July 2024 Vikas says: “The dust field seen in this image is the result of a four-panel mosaic. The dark skies of Chile and the light-hoover that is the Takahashi E-160D telescope made short work of capturing this fascinating region, and PixInsight's updated mosaic tools made assembling the four panels much easier.” Equipment: ZWO ASI6200MM Pro camera, Takashi Epsilon E-160D reflector, Software Bisque Paramount MX+ mount Exposure: Four panels, each R 30x 3’, G 30x 3’, B 30x 3’, Ha 30x 3’, total 24h Software: PixInsight Vikas's top tips: “When making a mosaic, keep the rotation of the panels in mind while PHOTO OF THE MONTH planning the overlaps.…