Innehållsförteckning för December 2023 från BBC Sky at Night

DECEMBER HIGHLIGHTS Interview: Fighting light pollution Dark Sky Officer Dani Robertson reveals how artificial light affects our view of the night sky, and how to fight it. The Sky at Night Question Time Special In this hour-long special, Maggie, Chris and Pete join a panel of experts to answer questions on space and astronomy. Make a model to show Venus's phases Download and print out our plans and guides to help you complete this month's DIY astronomy project, on page 74. The Virtual Planetarium…

An all-UK space mission could soon be heading into orbit with a crew of four British astronauts – and it's rumoured that veteran UK astronaut Tim Peake could be chosen to lead the mission. US spaceflight company Axiom Space has signed a memorandum with the UK Space Agency to begin arrangements for the mission, which would conduct experiments and outreach activities over a two-week stay in orbit. The £200m price tag would be funded by commercial partners, not the UK tax payer. “We want to put the UK at the forefront of the global race for commercial space investment, continue to support scientists and engineers to test new technologies and carry out important research and, ultimately, bring the benefits back to people and businesses across the country,” says George Freeman,…

A chaotic and broken region of Mars's terrain could provide an opportunity to investigate a rich vein of potential biomarkers on the Martian surface, a new study has revealed. The site has been put forward as the location of a future landing mission. Liquid water once flowed across Mars, meaning it could potentially have been habitable. In order to search for signs of past life, geologists seek out areas that could be rich with ‘biomolecules’ – the chemicals that form the building blocks of life. One place such chemicals would have collected is in underground aquifers, which would occasionally flood the planet's surface. “As the water was released to the surface and ponded, the water went away leaving behind [layers] of sediments and potentially high concentrations of biomolecules,” says Alexis…

The speed of light enchants the sky. It adds another story to the night. Curiosity, whether scientific or artistic, adds dimensions to the world we walk through. One of the objectives of The Infinite Monkey Cage, the radio series I have presented with Brian Cox for 14 years, is to excite as well as to inform. We don't just want people leaving an episode with more ‘facts’, we want them to depart with a new excitement and emboldened fascination. I have always felt this about The Sky at Night, too: the most important concern of each episode is to encourage you to spend more time looking upwards and outwards, beyond our atmosphere and back in time. I am not an astronomer, but I spend a lot of time looking up…

One of the biggest issues with studying the CMB is noise. Each CMB photon has picked up information from every stage of the Universe it's travelled through, meaning the initial fluctuations make up only a few per cent of the signal picked up by an observatory. Throughout its journey, a light photon has been bent and distorted by the large-scale structure of the Universe, resulting in the weak lensing signal. This not only changes its path slightly, but also distorts both its temperature and polarisation, and so using these two measurements in concert can be used to extract that signal. Next, the photon enters our Galaxy, where it encounters a variety of obstacles. The Milky Way's magnetic field again affects the polarisation, which needs to be compensated for. Dust and…

Cassini Type: Crater Size: 58km Longitude/latitude: 4.7° E, 40.3° N Age: 3.8–3.9 billion years Best time to see: First quarter (19 December) or six days after full Moon (4 December and 3 January) Minimum equipment: 50mm refractor Cassini is an example of a ring plain crater, a narrow rim enclosing a relatively flat floor area (aside from some obvious exceptions). The rim is complete all the way round and rises to around 1.2km high, decreasing to 460m on the eastern side. The whole structure is surrounded by a rather impressive ejecta rampart, a very obvious feature as Cassini sits on the flat northeast lava surface of 1,250km Mare Imbrium. The most prominent of those ‘obvious exceptions’ on Cassini's flat floor is the elongated form of the 17km bowl-shaped crater Cassini…

1. The Hyades The Hyades cluster is next to mag. +1.0 Aldebaran (Alpha (α) Tauri), the reddish eye of the Bull, which is not part of the cluster but a foreground star. The cluster is only 153 lightyears away, making it the nearest open cluster to us. In mythology, the Hyades were the daughters of Atlas, and their weeping for their brother Hyas, who was slain by a lion, is the rain that is associated with their heliacal setting in spring. ■ SEEN IT 2. NGC 1647 About 3° northeast of Aldebaran is a lovely little cluster, NGC 1647, often ignored because of the presence of its more prominent neighbour. With 10x50s you should be able to see eight or nine stars against a background glow about one and a…

Staring up at the Moon with the naked eye, we can forgive early astronomers for assuming the dark patches spread out over its surface were seas – or ‘maria’ as they were named, after the Latin word for seas. Informed by centuries of ever-improving observations and over 60 years of space exploration, we now know the maria are not seas but rather vast expanses of volcanic basalt that erupted over the lunar surface several billion years ago The Moon is in fact very dry: more so than any desert on Earth. Yet despite that, on 23 August 2023 the Indian Space Research Organisation's Chandrayaan-3 mission successfully deployed its lander and rover near the lunar south pole in search of water. So why search for water in such a dry location?…

M any new telescope packages come with a basic eyepiece or two, good enough to help you get started with the hobby and familiarise yourself with your equipment. Plenty of experienced astronomers will hold fond memories of their first view of Jupiter or Saturn through these starter eyepieces. But it doesn't take long until you start wondering… how much better would the view be through a different lens? It's fair to say, though, that the choices on offer can be bewildering. Especially given the nomenclature: you might hear of Plössls, orthoscopics, radians and Naglers, or even Kellners and Erfles, and find each costing anywhere between £25 to an eye-watering £1,000 plus – which is perhaps more than the telescope itself! However, if you can decipher all these terms, you should…

Three years ago, Venus hit the headlines when the presence of phosphine gas, a possible life signature, was discovered in the planet's atmosphere. Phosphine, comprising hydrogen and phosphorus, can be found on Earth as the product of natural processes such as volcanic activity, but is also created by anaerobic bacteria living in marshlands and bogs. Could Venus's atmosphere, filled with boiling clouds of sulphuric acid, be home to a similar, yet alien, microbe? Using the James Clerk Maxwell Telescope (JCMT) in Hawaii in 2017, a team of astronomers led by Professor Jane Greaves of Cardiff University discovered a tantalising hint of the gas in the skies over Venus. Confirmation was later obtained from observations by the Atacama Large Millimeter Array observatory in Chile in 2019. Controversy soon surrounded the announcement…

Star trails images are a very rewarding type of nightscape photography. Capturing the movement of the stars as Earth rotates on its axis is beautiful in itself, but when it incorporates a nice foreground it really elevates the shot. The great thing about star trail photographs is that they're very easy to produce and can be done with very basic camera equipment. In addition to shooting images with the intention of creating star trails, you can also create them from photographs taken during other imaging sessions. For example, if you've been photographing a meteor shower, aurora display or even a noctilucent cloud display, as long as your camera was on a static tripod and has not been nudged, you can take the images and create a star trail photograph with…

HUBBLE SPACE TELESCOPE, 23 OCTOBER 2023 Individually, the two galaxies in this image – which lie 500 million lightyears from Earth in the constellation of Tucana – are known as NGC 7734 (top left) and NGC 7733 (bottom right). Collectively, they're known as Arp–Madore 2339-661, the moniker given to them when they were described in the Arp–Madore catalogue of peculiar galaxies, which was compiled in the 1970s and ’80s. A closer look, though, reveals that the two galaxies are actually three. Roughly two-thirds of the way along the blue upper arm of NGC 7733, you can see what appears to be a small clump of brown matter. Astronomers now believe that this is a third galaxy, provisionally now referred to as NGC 7733N. As the three galaxies are in very…

The interconnected series of gas filaments that stretches between galaxies, the Cosmic Web, has been mapped for the first time. “The Cosmic Web delineates the architecture of our Universe,” says Christopher Martin from the California Institute of Technology, who led the study. “It's where most of the normal, or baryonic, matter in our Galaxy resides, and directly traces the location of dark matter.” Until now, astronomers have only been able to glimpse the gas within the Web when it is being illuminated by a bright quasar, meaning the thin filaments between galaxies have remained in the dark. To trace out these previously invisible pathways, Martin's team used the Keck Observatory in Hawaii to pick out a specific wavelength of light created by hydrogen gas within the streams called the Lyman…

Our experts examine the hottest new research CUTTING EDGE One of the most stunning discoveries delivered by NASA's Cassini probe to the Saturn system was that its moon Titan hosts a number of lakes (confirming evidence from the Hubble Space Telescope). Titan is a giant moon with a thick atmosphere, and had long been suspected to offer appropriate conditions for bodies of liquid methane and ethane on its surface. The largest of these, Cassini found, range from hundreds of kilometres to over 1,100km in length, and so are referred to as seas. The probe also spotted hundreds of other smaller lakes, ranging from just a few kilometres to 240km. Some of these bodies exhibit intricate shorelines, and many cluster together near the north pole: a Titanic Lake District. Seas and…

See the Geminid meteor shower's peak Sutton Bank Star Hub, Thirsk, North Yorkshire, 13 December, 7pm Renowned dark-skies campaigner and astronomy educator Richard Darn (of Dark Skies UK) hosts a public observing session, timed to coincide with the peak of the Geminid meteor shower, in the plush surroundings of Sutton Bank Star Hub. Located in Sutton Bank National Park, the hub was purpose-built for astronomers in 2021 and features a warm, comfortable indoor area for talks and presentations – in this case, a planetarium show in the event of bad weather – as well as an outdoor viewing area with room to set up telescopes. Tickets are £20, £15 for under 16s. Early booking is advised as numbers are strictly limited. bit.ly/3FhuQy0…

Light is the window through which astronomers view the cosmos. It fills the Universe. Once light has been emitted, it travels on and on, moving constantly at the speed of light. It only stops when it hits something, be it a gas particle, a planet or even a black hole. Because of light's eternal nature, we see distant galaxies not as they are now, but as they were when their light was emitted. If it has taken the light from an object a billion years to reach us from a galaxy, then we see that object as it was a billion years ago. Look far enough away, and you could view all the way back to when the first stars began to shine. Look back even further and it's possible…

BEST TIME TO SEE: 10-16 December The Geminid meteor shower is one of the big-hitters of the year. This is because it has a high peak Zenithal Hourly Rate (ZHR) and a relatively broad peak period. If the Moon is out of the way the weather kind, and you have dark skies the Geminids can be awesome. This year, the Moon is out of the way. It's in an early phase and sets fairly early on. The unknown is the weather and during December this can be an issue. Activity starts early December, low ZHR rates producing the odd Geminid during an all-night session. Things start to get interesting after 10/11 December in the run up to the peak period. This year, peak rates should occur on the nights of…

Uranus Best time to see: 1 December, 22:40 UT Altitude: 54° Location: Aries Direction: South Features: Weak banding, colour, brighter moons Recommended equipment: 200mm or larger Uranus is really well placed for viewing at the moment, having reached opposition in the middle of last month. It's able to attain a maximum altitude of 54° under truly dark skies as seen from the centre of the UK, maintaining this capability all month long. It's currently shining at mag. +5.6 and located less than 3° south of mag. +4.3 Botein (Delta (δ) Arietis). Botein is a great navigational tool for finding Uranus. Using average binoculars (7×50), locate and place Botein at the centre of the field of view. This should position mag. +4.6 Epsilon (ε) Arietis near the edge of the field.…

Minor planet 4 Vesta reaches opposition on 21 December when it can be found shining at mag. +6.6 among the stars of northern Orion. To fit within the IAU defined boundary of northern Orion is quite a feat, as this portion of the constellation, the bit north of his club and beneath the foot of the twin Castor in Gemini, is only 7.4° wide. Vesta manages to stay within this boundary until 29 December when it slips slightly across the border into Taurus. Vesta begins the month 3.1° south-southwest of mag. +2.8 Tejat (Mu (μ) Geminorum). From here it tracks west and slightly north to pass just north of mag. +5.8 68 Orionis on 8 and 9 December, mag. +4.6 Chi2 (χ2) Orionis on 16/17 December and mag. +4.4 Chi1…

Most of us have seen a meteor trail at one time or another, the rapid streak of light caused when a small, typically sand-grainsized particle vaporises in Earth's atmosphere. If you haven't caught one yet, December is a good time to try as it hosts the peak of arguably the best meteor shower of the year, the Geminids. This month's challenge is to try to observe a phenomenon associated with bright trails: a meteor train. The Geminid shower is active from 4 to 17 December, with heightened activity from the 9th to the 16th. It peaks on the evening of 14 December, meriting all-night watches on the nights of 12/13, 13/14 and 14/15 December. If it's clear and you attempt this, you'd be very unlucky not to see meteor trails.…

Today, over 1,000 quintillion litres of water exist on Earth, most of which make up the oceans that cover over 70 per cent of its surface. Our Blue Planet may be blue now, but things may have been quite different when it first formed. In some formation theories, the early Earth was initially dry, having formed in the inner region of the Solar System inside the so-called ‘snow-line’, close to the Sun, where temperatures are so high that volatiles like water are in their gaseous form. The snow-line is the distance from a star beyond which temperatures on a planetary body become low enough for water to condense out from gas and form solid icy grains. In this scenario, it is believed that Earth's water was delivered later by impacting…

There are a great many types of eyepiece on offer, but essentially, the difference between them is the apparent field of view. This is measured in degrees as seen by the observer. The human eye can see around 180° in the horizontal plane, and so the closer to this an eyepiece gets, the more immersive your viewing experience will be. Generally, the wider the view on offer, the more complicated the eyepiece's design and the higher the price At the narrower end of the scale, orthoscopic and Plössl designs offer around 40° and 50° views respectively, and are popular for smaller targets, such as planets, lunar craters and double stars. As a middle-of-the-road option, there are a good variety of lenses available between 62° and 82°, such as those on…

Many of us start out by observing the so-called ‘lollipops’ of our Solar System, bright, easy-to-find objects like the Moon, Saturn and Jupiter. For the deep sky, it's the brighter Messier objects, such as M13, the globular cluster in Hercules, or M57, the enchanting Ring Nebula in Lyra which draw the most attention. While you're attempting to locate these objects, it can be useful to have a wider view. Once pinpointed, you can swap to a higher power with more magnification to see more detail on the lunar surface or planets. Meanwhile, these same eyepieces will make deep-sky objects like M57 stand out more at higher magnification because the background sky appears darker. So as a minimum, two eyepieces would seem to be essential. When new telescopes come bundled with…

With all these elements taken into consideration – field of view, focal length, eye relief, exit pupil, barrel size, observing type and so on – an eyepiece collection becomes a very personal thing, tuned to your individual requirements, equipment and preferences. However, there is always room for more options, and even though it can only be enjoyed during daylight hours, there is something deeply satisfying about matching sets of eyepieces, and even in matching the colour trim of the eyepiece to the telescope! Whichever direction your tastes dictate, a well thought-out eyepiece assortment will keep you coming back to the telescope, and allow you to relish all the delights of the night sky.…

This month's project is a model that demonstrates the phases of Venus as we see them from Earth. Our model utilises two table tennis balls and some thin plywood. It is operated by a hand crank which rotates the Venus ball around the central Sun ball, while markings on the top indicate significant points around the orbit. The hemisphere of the Venus ball facing the Sun is painted yellow, while the opposite side is black. We added optional LEDs inside both balls to enhance the contrast (although the only source of light is the Sun). The model very effectively demonstrates some interesting features of the orbit of Venus. Venus (along with Mercury) is an ‘inferior’ planet, which means it orbits nearer to the Sun than Earth does. They are normally…

Astronomers have spotted a rare burst of light that's thought to be one of the Universe's brightest phenomena, but it has only served to deepen the mystery of what causes these unusual events. Luminous Fast Blue Optical Transients (LFBOTs) are very blue in colour and evolve rapidly, reaching their peak brightness and then fading away in a matter of days. Their short-lived nature makes them difficult to spot, and the first, dubbed ‘the Cow’, was only discovered in 2018. Since then, they've been spotted at a rate of about one per year, mostly in the spiral arms of local galaxies. That led astronomers to believe they were unusual supernovae generated by huge but short-lived stars. This latest event, though – called AT2023fhn or ‘the Finch’, and first observed on 10…

The sample brought back from asteroid Bennu by NASA's OSIRIS-REx mission is rich in water and carbon, according to initial studies. On Earth, carbon and water form the building blocks of life. As Bennu dates from around 10 million years after the Solar System formed, the find could give vital insights into how these life-giving chemicals arrived on Earth. The sample was returned to Earth on 24 September 2023 and was transported to the Johnson Space Center to be opened. The science team there performed an initial investigation, scanning the interior of one of the grains and conducting a basic chemical analysis, which revealed the water and carbon. Once this primary assessment is complete, the sample is to be distributed to over 200 scientists around the world for detailed analysis.…

The UK is to play a key role in LiteBIRD, a new Japanese-led mission to study the cosmic microwave background radiation (CMB). The mission will analyse the light left over from the Big Bang, with the primary goal of hunting for the primordial gravitational waves that shaped the CMB during its formation. The UK Space Agency plans on investing a total of £17m in the mission, which is currently due to launch by 2030. This funding will go to UK scientists designing elements of the science instruments, as well as to a team at Cardiff University who are designing and producing the telescope's lenses and filters. “We expect LiteBIRD to be a game-changer for our understanding of cosmology, putting our best theories to the test as to what happened at…

In ancient times, when people looked up at the night sky, the stars were more vivid than they are today, as there wasn't the light pollution of modern times. People came to recognise patterns in the arrangement of stars. To them, one group of stars might look a bit like a woman seated on a throne, another like a dog or a bear. They wove these characters into the stories they told, interweaving culture with pinpricks of light. Today we call these patterns of stars constellations. The word ‘constellations’ is derived from Latin and means ‘set of stars’. These largely stem from ancient Greek interpretations of the star patterns in the night sky. However, this is just one interpretation of star patterns. Different people and cultures have seen completely different…

Lepus the Hare is a small constellation to the south of Orion the Hunter, the prey for Orion and his two dogs, Canis Major and Canis Minor. A crude description of Lepus is that it looks like the symbol for infinity (∞) with ears. The ‘pinch point’ in the centre of the symbol is represented by Arneb (Alpha (α) Leporis) and Nihal (Beta (β) Leporis). Arneb, its name derived from the Arabic for ‘hare’, shines at mag. +2.6, slightly brighter than mag. +2.8 Nihal to its south. In Chinese it is one star of an asterism formed from Alpha, Beta (β), Gamma (γ) and Delta (δ) Leporis called Cè, which means ‘toilet’. Alpha is known as ‘Cè yī’, ‘the first star of toilet’. Arneb's subtle appearance beneath mighty and dominant…

Liquid water is an essential requirement for life as we know it. It acts as a solvent, breaking down and dissolving substances into a form that can be used by life, also providing a liquid medium in which they can then move, interact with other substances and take part in the key chemical reactions that define life. The presence of liquid water is therefore considered a key requirement for any potentially habitable location beyond Earth, with NASA adopting the mantra ‘follow the water’ in its search for evidence of past and present life on Mars, and the study of its potential habitability. Indeed, the presence of water is used to define the ‘habitable zones’ around stars – these are the range of distances from a star at which an orbiting…

Christiaan Huygens, a Dutch astronomer, first hypothesised the existence of Venus's atmosphere in 1698 when he observed the planet through his telescope. Despite viewing its waxing and waning phases, he could not see any features on its surface and guessed that a thick atmosphere must be obscuring his view. Years later in 1761, Russian Mikhail V Lomonosov detected the refraction of solar rays while observing the transit of Venus across the Sun – and thus discovered the atmosphere of Venus. In 1962, Venus became the first planet to be visited by spacecraft, when NASA's Mariner 2 flew within 34,854km of the planet. Since then, nearly 40 missions have visited Venus and this month marks the 45th anniversary of NASA's Pioneer Venus mission and the Soviet Venera 11 and 12, all…

MORE ONLINE A gallery containing these and more of your images PHOTO OF THE MONTH The Soul Nebula Giuseppe De Pace, Turin, Italy, July–August 2023 Giuseppe says: “I chose IC 1848, the Soul Nebula, as my target due to its intricate detail and stunning colour palette. The data capture for this image was challenging as I had to battle against light pollution and bad weather, but the processing went smoothly and I'm pleased with the end result.” Equipment: QHYCCD QHY268M Pro camera, Askar FRA600 f/5.6 astrograph, Sky-Watcher AZ-EQ6 GT mount Exposure: SII 76× 300”, Ha 62× 300”, OIII 81× 300”, R 30× 120”, G 30× 120”, B 39× 120” Software: PixInsight, Photoshop Giuseppe's top tips: “My advice for astro imagers is to invest in a good-quality telescope or lens with…

The 6-inch aperture and 1,200mm focal length of this Newtonian are an excellent choice for a first telescope. As a reflector, the 6-inch aperture collects enough light to provide pleasing views of a wide range of astronomical objects, while remaining compact enough to still be portable. These attributes help to encourage newcomers to astronomy, as they won't be limited to just observing the Moon: detailed and inspiring views of galaxies, star clusters and planets can also be enjoyed. The Newtonian optical design also gives beginners access to higher magnifications, allowing close-up views of nebulae that would appear much smaller if using a refractor of a similar price. This gives plenty of scope for users to enjoy this reflector even once they've become more experienced as visual astronomers. Ursa Major has…

The telescope comes with a front-mounted solar filter. It is imperative that filters like this are securely attached to the front of the telescope with no risk of them being dislodged, to ensure the protection of your eyesight. This filter is securely mounted within a yellow plastic ring that in turn fits firmly inside the front of the dew shield, making it very safe if it's used carefully (and only under adult supervision if children are going to be using the telescope). This type of filter has a reflective surface that cuts out about 99.99 per cent of the light passing through it. Such filters allow you to observe the Sun's visible surface, the photosphere, in ‘white light’, making it possible to discern the texture of this layer, known as…