Indholdsfortegnelse for October 2023 i BBC Sky at Night

The latest astronomy and space news, written by Ezzy Pearson BULLETIN Stellar waves that tower as high as three Suns stacked on top of each other appear to be sweeping across the surface of a giant star, according to a new study. The star is the most extreme known example of a ‘heartbeat’ star. These are pairs of stars locked in an elliptical orbit, where the gravitational pull of one distorts the other, elongating it. As the stars orbit each other, the angle we view them at changes. When the elongated side faces towards us the star looks brighter, while the compressed side appears dimmer. In most heartbeat stars, the variance is only around 0.1 per cent of the total brightness. However, with this one, MACHO 80.7443.1718 – a 35-solar-mass…

The ultra-magnetic remains of dead stars – known as magnetars – are the most powerful magnets in the Universe, but their origin has long been a mystery. That could soon change, however, thanks to a recent set of observations of a mysterious helium-rich star. HD 45166 is around two times more massive than our Sun, but its unusual behaviour has defied explanation. That was until Tomer Shenar from the University of Amsterdam realised it could be highly magnetic, something not normally seen in massive helium-rich stars. Using telescopes from around the world, Shenar and his team discovered the star had a magnetic field of 43,000 Gauss (for comparison, our Sun is around 1 Gauss). “The entire surface of the helium star has a magnetic field almost 100,000 times stronger than…

MESSAGE OF THE MONTH This month's top prize: two Philip's titles The ‘Message of the Month’ writer will receive a bundle of two top titles courtesy of astronomy publisher Philip’s: Nigel Henbest’s Stargazing 2024 and Robin Scagell’s Guide to the Northern Constellations Winner ’s details will be passed on to Octopus Publishing to fulfil the prize Now you see it… In your excellent recent Virtual Planetarium video, Pete Lawrence and Paul Abel revealed night-sky highlights in July. They talked about viewing the crescent Venus, especially in daylight. One feature they debated was whether it’s possible to ‘see’ the outline of the whole planet when it’s in its crescent stage, pondering if it is truly something you see or something your brain does for you – sort of like completing the…

Watching a crescent Moon slowly drift westward in the fading light of an evening sky may not be all that scientific, but it does serve as a reminder that perhaps we aren’t the only ones drawn to its movement across the heavens. Indeed, humankind is just one of many living things touched “By the Light of the Silvery Moon”, as Doris Day sang in the 1953 film of the same name. The umbilical-chord existence that tethers Earth to the Moon is an incredibly strong bond, as both worlds duet their way around the Milky Way – a bond that’s absolutely crucial for so many species. For the baby turtle after hatching amid the sand, the gaze of its freshly opened eyes focuses in on the moonlight reflected off the nearby…

Markab (Alpha (α) Pegasi) is one of the four corner stars of the Great Square of Pegasus, the one that marks the southwest corner to be precise. It’s the third brightest in the Square, shining at mag. +2.5. Magnitude +2.1 Alpheratz (Alpha (α) Andromedae) in the northeast and mag. +2.4 Scheat (Beta (β) Pegasi) in the northwest are a little brighter, while mag. +2.8 Algenib (Gamma (γ) Pegasi) in the southeast is the faintest. The name Markab derives from the Arabic for ‘saddle of the horse’. In Chinese culture it forms an asterism with Scheat called the encampment, Markab being the ‘first star of the encampment’. The Square stars are white with the exception of Scheat, which appears orange. Markab is an evolved subgiant star of spectral classification A0 IV.…

Look at the large-scale structure of the Universe today and countless galaxies are strung out on endless filaments in a cosmic web. It seems that tiny variations in density in the very early Universe acted as seeds from which this structure eventually blossomed. Over-dense regions drew in more and more material to create galaxy-filled superclusters and leave behind supervoids. Except the Big Bang theory says that the early Universe should have been completely smooth. How come it had tiny imperfections of just a few parts in one hundred thousand, but which created the Universe as we see it today? One explanation is a modification to the Big Bang, called inflation. It argues that the Universe underwent a period of super-rapid expansion in the first miniscule fraction of a second. The…

There’s something about galaxies that just doesn’t make sense – they’re rotating far too fast. So fast that their outer stars should fly off into space, but that’s not happening. Instead, astronomers suspect that galaxies contain an invisible gravitational glue called dark matter that helps to keep hold of those stars. But what is dark matter made of? For decades the leading idea has been something called Weakly Interacting Massive Particles (WIMPs). Except physicists have gone to great lengths and performed extensive and exhaustive searches for them, and they haven’t seen a single one. And so they’re starting to look seriously at other options. Other candidates include the gravity of tiny black holes formed shortly after the Big Bang, known as primordial black holes. Or dark matter could be particles…

There are hundreds of billions – perhaps even trillions – of galaxies in the modern Universe, but where did all these starcities come from? There appear to be two ways to make a galaxy. You could start small with individual stars and minor star clusters. Over time, gravity, added by the glue of dark matter, could then bind lots of these together to form the conglomerations we call galaxies. This is a so-called ‘bottom-up’ approach. The alternative is ‘top-down’, where huge structures form early in the Universe’s history only to fragment into galaxies as the cosmos aged. The JWST is currently wowing astronomers with insights into the early Universe. It has seen fully-fledged galaxies just 400 million years after the Big Bang and even some that appear to be merging.…

Practical astronomy projects for every level of expertise Astrophotography can be quite unforgiving, exposing our cameras to conditions that push their design capabilities. One big issue is dirt, often in the form of dust, which builds up on the sensor from all those long nights outside in the elements. Cameras used for daytime landscape, portrait or traditional forms of photography spend their lives with camera lenses firmly secured to the front of the body, theoretically sealing the dust and general dirt out. Exposure times are usually fractions of a second too, which exposes the camera sensor to the air for relatively short periods of time. In astrophotography, however, our cameras are often attached to a telescope via a T-ring adaptor. This system is not sealed and so will allow dust…

Your best photos submitted to the magazine this month PHOTO OF THE MONTH The Elephant's Trunk Nebula Vikas Chander, Animas, New Mexico, USA, 15–23 July 2023 Vikas says: “I started out fascinated by the colours of the Hubble palette and narrowband imaging, but now find myself leaning more towards the RGB and broadband colour palette, thanks to images like this one!” Equipment: FLI ProLine PL16803 camera, PlaneWave CDK17 f/6.8 astrograph, Software Bisque Paramount ME mount Exposure: L 27× 1,200”, R 16× 900”, G 16× 900”, B 16× 900”, SII 18× 1,800”, Ha 18× 1,800”, OIII 18× 1,800” Software: PixInsight, Photoshop, Voyager Vikas’s top tips: “My recommendation to someone starting out is not to buy any equipment yet, but rather join a community such as AstroBin or one of the many online astrophotography…

Anita Chandran interviews Professor Justin Spilker What did your investigation involve? We were looking for complex organic molecules called polycyclic aromatic hydrocarbons or PAHs. On Earth, they show up in smoke and smog, but they also form naturally in space. Using the James Webb Space Telescope (JWST), we were trying to set the record for the farthestaway galaxy in which we could see PAHs. We were looking at a very distant galaxy, SPT041847, which corresponds to looking very far back in time (because it takes time for light to travel to us). The light that JWST found has been travelling to us steadily for 12 billion years. When looking at this light, we spotted these molecules. Why were you looking for PAHs? Because they’re big molecules, as far as space…

OCTOBER HIGHLIGHTS Interview: A magnetic Solar System Michele Dougherty reveals how magnetic fields help in the search for habitable conditions beyond Earth. Black Holes: Searching for the Unknown Watch this episode of The Sky at Night in which the team discover the secrets and the science of black holes. APY 15: See all of this year’s winning images Browse all the images from 2023’s Astronomy Photographer of the Year, including runners-up and highly commended. The Virtual Planetarium…

The intense flares of red dwarf stars bombard surrounding planets, stripping them of their atmosphere, but a new study has found the process could be far from smooth. Red dwarfs’ complex magnetic fields mean their stellar flares are 100 to 1,000 times more intense than those of our Sun and have a huge impact on the growth of surrounding planets. Researchers observing AU Microscopii, a youthful red dwarf with an infant planet orbiting it once every 8.5 days, were surprised to find no signs the planet was losing its hydrogen atmosphere. However, looking again 1.5 years later, they could see huge amounts of gas loss. “We’ve never seen atmospheric escape go from completely not detectable to very detectable over such a short period when a planet passes in front of…

The moment I arrived at Paranal Observatory, I knew I didn’t want it to be my only visit. A fresh-faced PhD student only a couple of months into my studies, I had the opportunity to travel from the University of Leeds to collaborate with the astronomers in charge of operating the telescopes at the top of Cerro Paranal in the Atacama Desert, northern Chile. ESO now operates eight telescopes at the observatory under the umbrella term ‘The Very Large Telescope’ (VLT), and an additional survey telescope, VST, at the site. Thanks to the extreme dryness of the Atacama and the observatory’s remote location, Paranal Observatory has established itself as a world leader in studying our Universe at optical and infrared wavelengths. Fast forward eight years since I first set foot…

Supported by Liberty Specialty Markets Once again, astronomy photographers from around the world have battled it out to claim the prestigious title of Astronomy Photographer of the Year 2023. This year, entrants from 64 countries submitted over 4,000 incredible images. From these, the judges have selected the best in each of eight categories, as well as two special prizes for best newcomer and for processing data taken by professional observatories, as well as a special prize for entrants younger than 16 years old. You can see the spectacular winning photos for yourself at the National Maritime Museum in Greenwich, London from 16 September. For details, visit www.rmg.co.uk/astrophoto. FREE 2024 CALENDAR Don’t miss the December issue of BBC Sky at Night Magazine for our free 2024 calendar featuring all the incredible…

BEST TIME TO SEE: 28 October, from 19:02 BST (18:02 UT) until 23:26 BST (22:26 UT) The Moon passes into Earth’s shadow on 28 October, creating a lunar eclipse. This will be an interesting event because the Moon will graze the northern edge of the darkest portion of the shadow. This results in a small ‘bite’ appearing to be taken out of the Moon’s southern edge. From Earth, the Sun has an apparent size around half-adegree. In other words, it’s an extended rather than a point-source of light. The consequence of this is that from the Moon’s orbital distance, Earth’s shadow has two components: a weak outer part known as the penumbral shadow and a dark inner part called the umbral shadow. A spacecraft within the outer part of the…

1. Kurhah star field 10× 50 The very white mag. +4.4 Kurhah (Xi (ξ) Cephei) is the most northerly and brightest star of a lovely group that stretches southward for about 3°. There are some very red stars like mag. +5.2 18 Cephei and, at the other extreme, hot blue mag. +5.1 19 Cephei. Give yourself time to appreciate the sheer variety of what’s on show and look around for the other, fainter groups of colourful stars that lurk nearby. □ SEEN IT 2. U Cephei 10× 50 Eclipsing variable star U Cephei lies midway between two white mag. +5.6 stars, 7.5° from mag. +2.0 Polaris (Alpha (α) Ursae Minoris) in the direction of mag. +2.1 Gamma (γ) Cassiopeiae. Its magnitude range is +6.8 to +9.2, a nine-fold variation in…

On 6 October 1923, the American astronomer Edwin Hubble used the 100-inch Hooker Telescope at the Mount Wilson Observatory in California to photograph the Andromeda Galaxy. The calculations that resulted solved one of the biggest unanswered astronomical questions of the day by proving that Andromeda, and other ‘spiral nebulae’ like it were actually huge galaxies millions of lightyears away, rather than small objects closer by, within the Milky Way. The discovery changed astronomy forever by showing just how vast our Universe truly is. Exactly a century later, technology may have massively improved, but there are still many unsolved mysteries surrounding our Universe. Here are some of the most pressing issues occupying the finest astronomical minds of the 21st century.…

When Edwin Hubble discovered cosmic expansion in the 1920s, it was a major clue that the Universe began with a Big Bang – the point at which the expansion began. Hubble found that distant galaxies appear to be moving away from us faster than those nearer to us. Galaxies aren’t really moving through space, though – it’s the space between galaxies that’s stretching as the Universe expands. The more space there was between us and a galaxy to begin with, the faster that galaxy seems to recede when that space gets bigger. This led to the idea of a so-called Hubble constant, which measures the rate of expansion in the current Universe. When measured from objects in the nearby cosmos, it has a value of 73 kilometres per second per…

Astronomers used to think that the gravity of everything in the Universe would eventually pull the cosmos back in on itself in a reversal of the Big Bang, dubbed the Big Crunch. However, that was before they discovered that the expansion of the Universe is accelerating due to a shadowy entity known as dark energy. If it continues to accelerate, all structures in the Universe – even atoms – will be torn apart within 22 billion years in a so-called Big Rip. A more sedate expansion would lead to a Big Freeze instead, where the expansion of the Universe causes it to cool so much that stars cannot shine and the Universe eventually settles into a uniform temperature.…

The fundamentals of astronomy for beginners The mere mention of a solar eclipse may conjure thoughts of totality and a glimpse of the Sun’s ghostly corona, the outermost part of its atmosphere, as day turns to night. These are two effects of a total solar eclipse, but what will take place across the US in October is a different kind: an annular solar eclipse. Although the corona remains out of sight and daylight persists during these eclipses, they have other spectacular features, notably the ‘ring of fire’. That’s what will be visible on 14 October 2023 when people across the southwestern US, and Central and South America will see a thin, burning ‘ring’ around the Moon for over four minutes, as 90 per cent of the Sun is blocked. Remarkably,…

Take the perfect astrophoto with our step-by-step guide How many times have you seen a star described as ‘red’ appearing slightly orange, or called ‘blue’ but looking white? By building a library of star photos you’ll be able to see their subtle colour variations. A large library will create a very impressive display and will spectacularly show just how different star colours can be. Photographing stars isn’t hard, but capturing their colour is a bit more challenging. A star is a point source of light, which normally photographs as an over-exposed white dot. In addition, Earth’s atmosphere wobbles the star’s light due to microrefraction, causing it to ‘paint’ over a larger area. The worse the seeing, the larger the star’s dot becomes in your photos. The colour is there, but…

Our experts review the latest kit UK-based Atik Cameras recently added a 16-bit astrophotography camera to its offering, in the shape of the Apx26. It’s a 26-megapixel CMOS camera available in both mono and one-shot-colour variants. Our review model is a monochrome version which we paired with an Atik electronic filter wheel to take images using our 2-inch filters. During these economically challenging times, comparing the cost of equipment to apparently similar offerings is often worthwhile. The Atik Apx26 Mono is at the higher end of the price range when compared to other cameras using the same CMOS sensor, so we were especially keen to discover what sets the Atik device apart from the competition. Well, right out of the box, the build quality and design of the Apx26 is…

EYE ON THE SKY JAMES WEBB SPACE TELESCOPE, 21 AUGUST 2023 The Ring Nebula, M57, has been a familiar sight to stargazers since 1779, when it was first observed by Charles Messier. But now, nearly 250 years on, new images from the James Webb Space Telescope have captured this old favourite in greater detail than we've ever seen before. This picture was taken using the NIRCam instrument and shows that the planetary nebula’s supposedly ‘empty’ central region is actually full of filaments of very hot gas. These, like the rest of the nebula, are remnants of the now-dying star that lies at its very heart, which will eventually become a white dwarf. Then above is an image taken with JWST’s MIRI instrument, revealing spikes and arcs in the nebula’s outer…

BULLETIN Humanity has landed on the lunar south pole for the first time, after the Indian lunar mission Chandrayaan-3 touched down on 23 August. The mission was the Indian Space Research Organisation’s (ISRO) second attempt to land on the Moon, after Chandrayaan-2 crashed into the lunar surface in 2019. “Chandrayan-3 scripts a new chapter in India’s space odyssey,” says Indian Prime Minister Narendra Modi. “It soars high, elevating the dreams and ambitions of every Indian. India is now on the Moon. The sky is not the limit.” The mission’s Vikram lander (named after ISRO founder Vikram Sarabhai) set down on the surface at 12:34 UT. After waiting several hours for the dust kicked up by the landing to settle, the lander deployed a ramp allowing its rover, Pragyan (Sanskrit for…

Our experts examine the hottest new research CUTTING EDGE Exoplanet hunters have a number of different ways of detecting worlds around other stars in the Galaxy – such as observing how the star is tugged around slightly by the orbiting planet’s gravity, or its starlight being partially blocked by a transiting planet. But how else might astronomers be able to indirectly infer the existence of an unseen planet around a star? One idea that’s been floating around for a little while now is the possibility of detecting exoplanets by the radio waves emitted through magnetic interaction between the star and planet. The underlying process is well known for Jupiter and its moon Io. As Io orbits around Jupiter and through its powerful magnetic field, charged particles from the moon are…

Watch This Space The Concorde Club, Southampton, 8 October, 7:30pm Ever longed to unlock the secrets of the distant cosmic objects we see in the night sky? In this new touring show, astronomer, astrophotographer and former BBC Sky at Night Magazine news editor Will Gater, FRAS, who’s been described as “one of the current generation of ‘rock star’ science popularisers”, blends visuals, live demonstrations and inspiring storytelling to take the audience on a journey out into the Milky Way and beyond as he delves into the big questions: what’s ‘out there’ and what is our place in the Universe? The show moves on to Pershore, Worcestershire next month, with more dates to be announced. Tickets £25. willgater.com/watchthisspace…

Jupiter Best time to see: 1 October, 00:15 BST (30 September, 23:15 UT) Altitude: 51° Location: Aries Direction: South Features: Complex atmosphere, Galilean moons Recommended equipment: 75mm or larger telescope Jupiter reaches opposition on 3 November, and throughout October is well-placed for observing. From the UK, it’s able to reach its highest position, around 51° up when due south, under truly dark skies. It’s also very bright, shining at mag. –2.8. Consequently, it’s a great time to observe and image this amazing world. Through a small telescope, Jupiter’s disc is obvious and appears squashed. Being a gas planet and rotating rapidly in under 10 hours, Jupiter’s equatorial regions bulge and give the planet its oblate appearance. If you give your eyes time to adjust to the view, the first detail…

Comet 103P/Hartley, known as Hartley 2, is in a good position as it approaches perihelion on 12 October. At peak brightness the comet may reach mag. +8.5 but as it was relatively close to Earth in late September, it’ll probably appear large and diffuse. Hartley 2 is a morning object during October, its month track beginning in Auriga but quickly passing into Gemini. It crosses the main form of the stick-figure twins between 5 and 11 October, lying very close to mag. +3.5 Wasat (Delta (δ) Geminorum) on the night of 10/11 October. As this coincides with the comet approaching peak brightness, the early hours of 11 October should be a good time to look for it. The only negative is the Moon in Leo, 9° east of Venus. This…

A total eclipse of the Moon is typically quite colourful. What you would expect to be a totally dark shadow of Earth is infilled with light refracted through our planet’s thin skin of atmosphere. This not only brings light to the otherwise dark shadow, but it also brings colour from what is essentially a continuous ring of sunrise and sunset as seen from the vantage point of the Moon. The red colouration is obvious when the Moon is completely covered by Earth’s shadow, but can it be seen or photographed during a partial eclipse? This is the subject of this month’s challenge. If it’s clear on 28 October, from the UK we’ll be able to see a slender portion of the Moon’s disc covered by the darkest, umbral, portion of…

Our current best theory of gravity is Einstein’s general theory of relativity. It says that massive objects like the Sun warp space-time, the fabric of the Universe, around them. Earth is then caught in the distortion that the Sun makes, which is why we orbit. Except this isn’t how physicists treat any of the three other fundamental forces. They are all carried by particles called bosons. Magnets attract each other, for example, by exchanging bosons called photons. So the hunt is on for the graviton – a so-far-hypothetical particle that would be responsible for gravity.…

Every subatomic particle has a mirror image – a particle of antimatter. When an ordinary particle meets its antimatter counterpart they annihilate in a flash of light. Matter and antimatter should have been created in equal quantities after the Big Bang and should have completely annihilated by now. Yet the Universe is full of matter and very little antimatter. Astronomers suspect that for every billion antimatter particles, a billion and one matter particles appeared. All the antimatter annihilated with almost all the matter, leaving a tiny residue of matter. Yet we still don’t know why nature has a slight preference for matter over antimatter.…

If the artist’s impressions are anything to go by, we’re in for spectacular images in August 2029, when NASA’s Psyche spacecraft enters orbit around the asteroid with the same name. Psyche, slated for launch in early October, is the very first space mission to study an M-type (metallic) asteroid, and no one really knows what to expect. According to a number of recent studies, asteroid Psyche may sport volcanic ‘lava’ plains of pure iron or steep mountains of metal – something that has never before been seen in the Solar System. One thing’s for sure though: the Psyche mission (named after the asteroid, not the other way around!) will reveal the strange object’s nature, composition and evolution, and shed further light on the origin of the Solar System. “It is…

Expert processing tips to enhance your astrophotos One of the enjoyable aspects of astrophotography is exploring new techniques to improve your processing skills. Since originally processing my narrowband image, ‘The Runaway Star of Sh2-27’, shortlisted in 2022’s APY competition, my processing today is quite different. Sh2-27 is an extremely large ionisation nebula in Ophiuchus, which spans 13 degrees or 26 full Moons across the sky. I imaged it with a Nikon 200mm f/2 lens and a full-frame ZWO ASI6200MM camera, and even with the very large field of view with this setup, I still needed a three-panel mosaic to capture it all! First, I needed to remove any unwanted gradients from light pollution, moonlight and sky glow. After using the WBPP script in PixInsight to perform image calibration and registration,…

Our experts review the latest kit Atair Astro is no stranger to compact telescopes, with an established range of refractors offering apertures from 60mm to over 150mm. Its latest offering, the 70mm EDQ-R quadruplet astrograph, is a refractor designed with astrophotographers in mind. The ultra-portable tube is engineered to consider the needs of intermediate and advanced imagers, accommodating a variety of camera types from CCD and CMOS sensors to DSLR. The 70 EDQ-R’s four-lens optical system means you should expect pinpoint stars across an entire field of view and the focuser comes with various camera thread options, allowing the use of a range of different imaging equipment. This attention to detail lightens the accessory burden for deep-sky imagers; the extra glass in the system is specially positioned to negate the…