Indholdsfortegnelse for August 2021 i BBC Sky at Night

Dark matter-free galaxy confirmed The find challenges our knowledge of how galaxies form and stay together A distant galaxy could throw our understanding of galactic formation into question, after recent Hubble Space Telescope measurements have bolstered previous claims that it’s free of dark matter. According to our current understanding, galaxies are held together by a mysterious substance known as dark matter. Spheroidal galaxy NGC 1052-DF2 (DF2 for short), however, seems to be an exception to this rule. Although it is as wide as the Milky Way, the galaxy contains 200 times fewer stars, and initial measurements (made in 2018) suggest that it has 400 times less dark matter than astronomers think it should have – according to our current understanding of how galaxies grow and evolve. An alternate possibility, however,…

Hunting oceans on Uranus’s moons The planet’s magnetic field could help to see beneath the icy surface of its moons While the Galileo probe was looping around the Jovian system in the 1990s it detected something very strange about two of the larger moons. Galileo was equipped with a magnetometer – an instrument for measuring magnetic fields, a bit like an extremely sensitive compass needle – and every time the spacecraft performed a flyby of Europa or Callisto it sensed the field lines of Jupiter’s powerful magnetic field draping around the moons. The satellites seemed to possess a weak magnetic field that was interacting with that of Jupiter. These tiny, frozen moons can’t have been generating the magnetic field themselves by an active internal dynamo, as happens in Jupiter and…

DOCUMENTARY Online The Edge of All We Know An exhilarating documentary following the physicists working with Stephen Hawking on his final paper, on the black hole information paradox, and the Event Horizon Telescope team as they race to image a black hole (located at the centre of galaxy 087) for the first time. www.netflix.com TALKS Live Dark Sky site tour OM Dark Sky Park, Omagh, during August Travel through the Universe with your own star guide, experience space in virtual reality and ponder the mysterious connections between the sky and the area’s ancient stone circles. Tickets are £5 (adults) and £3.50 (children). Pre-booking is essential via omdarksky.com Live One Day on Mars Royal Observatory Greenwich, during August Enjoy a thrilling full-dome planetarium show touring the dunes and canyons of the…

Summertime astronomy in the UK can be something of a bleary-eyed marathon, with late-night observing sessions to grasp anything that seems like darkness amid the glow of twilight. Every August, though, we get our reward for persevering through these months in the form of the Perseid meteor shower and this year – if the skies are clear – we should. get a decent show. On the night of the shower’s peak, on 12 August, the Moon sets at around 22:30 BST (21:30 UT), which is well before the onset of astronomical darkness for much of the country; with no moonlight to wash out the sky, fainter meteors will be easier to spot. But what causes this wonderful celestial spectacle and what do you need to do to make the most…

If you read some of the media coverage of meteor showers like the Perseids, you might think that, at their peak, these events see a near-constant rain of bright shooting stars blazing across the sky. Real meteor showers – while captivating and absolutely worth observing – are rarely like this. One number that’s often mentioned is the Zenithal Hourly Rate, or ZHR; this is a theoretical number of meteors that would be visible, on average, over an hour with the radiant of the shower at the zenith and the viewing occurring under perfect sky conditions. The ZHR isn’t a good indicator of how many meteors you can expect to see every hour, however; that figure will be lower because of things like light pollution and the typically lower radiant at…

Carbon dioxide (CO2) accounts for just 0.04 per cent of Earth’s atmosphere, so how can it have such a big effect on the planet’s climate? Well, firstly, CO2 traps heat (hence it’s known as a greenhouse gas) and secondly, it remains in the atmosphere for centuries. Earth receives huge quantities of energy from the Sun in the form of sunlight. As this is short-wave radiation, it passes through the atmosphere largely unhindered. Most of that energy is absorbed by the surface, but about 17 per cent is reflected back in the form of heat (long-wave, infrared radiation). Infrared radiation effectively passes straight through oxygen and nitrogen (which comprise the vast majority of Earth’s atmosphere), thanks to their relatively simple molecular structure. But the molecular structure of CO2 is more complex,…

1 Sunday An unusual occultation of Europa by Ganymede occurs at 23:00 BST (22:00 UT) this evening. The relative motion of both moons means that Ganymede appears to cover part of Europa, which then appears to pull away again. See page 47 for more details. 2 Monday Saturn is at opposition today. A phenomenon known as the ‘opposition effect causes the planet’s rings to brighten and this should be noticeable through a telescope. This morning’s 35%-lit waning crescent Moon sits 6.7° south of the Pleiades. 3 Tuesday This morning’s 26%-lit waning crescent Moon sits 4.8° north of mag. +0.8 Aldebaran (Alpha (α) Tauri). 5 Thursday As this morning’s 12%-lit waning crescent Moon rises, it’ll be passing over the northern portion of open cluster M35. The event concludes around 02:40 BST…

1. 3, 4 and 5 Aquarii 10x50 4 and 5 Aquarii comprise a very easy double star, at mag. +5.5 and mag. +6.4 respectively, separated by 13 arcminutes. This is a line-of-sight pairing, not a true binary star. A degree or so to the northwest you will see a brighter orange star. This is the slightly variable (mag. +4.4 to +4.5) 3 Aquarii. If you enjoy looking at coloured stars, scan the region 5° northwest of 3 Aquarii. □ SEEN IT 2. M2 10x50 The globular cluster M2 forms a right-angled triangle with Sadalsuud (Beta (β) Aquarii) to the south and Sadalmelik (Alpha (α) Aquarii) to the east. It stands out, even in small binoculars, in an otherwise sparse region of sky, looking exactly as Charles Messier described it: “a…

Step 1 Download WinJupos from http://jupos.org. Run the freeware and select ‘Celestial Body > Jupiter’ under the ‘Program’ menu. Next, under the ‘Recording’ menu, select ‘Image measurement…’. In the subsequent window click ‘Open image’ (F7) and select your image. Step 2 Ensure the ‘Date’ and ‘Time’ for the image are correct in the ‘Imag.’ tab, before selecting the ‘Adj.’ tab (to the immediate right of the ‘Imag’ tab). Select the correct ‘Channel’ (F9) value for the image and ensure ‘Draw outline frame’ is selected. Step 3 The correct frame orientation and alignment is important. ‘Outline frame’ > ‘Automatic detection’ may work, otherwise use the cursor arrow keys to move position, ‘PgUp’/’PgDn’ to magnify/shrink and ‘N’ and ’P’ keys to rotate clockwise/counter-clockwise. Step 4 With everything set correctly, click ‘Save’ (F2)…

1. Look for NLCs in the northern sky, 90-120 minutes after sunset, between the end of May and start of August. They sometimes appear at the same time before sunrise. 2. Ensure you’re facing the right direction, by looking towards the bright star Capella (Alpha (α) Aurigae) in the constellation of Auriga. 3. If you plan to take photographs, use a tripod and an exposure time of between 2 and 6 seconds. 4. It’s hard to predict the weather but try and choose a day with clear skies. 5. Look out for white or electric blue clouds, maybe with a herringbone or rippling sand-type pattern.…

My winning entry in the ‘Stars and Nebulae’ category at the 2020 Astronomer Photographer of the Year competition is entitled ‘Cosmic Inferno’. It features the emission nebula NGC 3576, one the most intriguing nebulae in the southern skies. It has striking features, with great loops of ionised gas that stretch over 100 lightyears into the vacuum of space. Indeed, astronomers have identified polycyclic aromatic hydrocarbons within NGC 3576, hydrocarbons being an essential component for the formation of the earliest life on Earth. And 3.7 billion years after life first appeared on our planet, the bushfires of 2019-20 would raze the ecosystem across vast swathes of the Australian landscape of life – something alluded to in the title I gave to the image. My original intention was to take a colour…

Do you fancy having Go-To functionality without the hassle of motorised drives and a complex equatorial or altaz mount that costs a fortune? Well, this is where Celestron’s StarSense range comes into its own. By employing a clever app on your smartphone, combined with a carefully designed adaptor to hold it, the StarSense series does just that. As the StarSense Explorer DX 6-inch Schmidt-Cassegrain is currently the largest and latest offering in the series, we were keen to try it out. The StarSense Explorer DX 6 is a 6-inch (150mm) Schmidt-Cassegrain telescope, which uses a primary mirror at the rear, and a corrector plate and secondary mirror at the front to fold the light path into a short tube. It has a focal length of 1,500mm, giving a focal ratio…

Ezzy Pearson interviews Dr John Barentine Why do we want to prevent light pollution? What people think about first is protecting the night sky, but we have an increasing understanding of the significance of light pollution as part of the overall threat to our environment. We know that it has an effect on wildlife ecology, has a potential influence on human health, public safety and energy security – it’s not simply a matter of astronomy. How do satellites increase light pollution? Until recently we weren’t thinking about this issue. It came to the fore about two years ago with the first launch of the SpaceX Starlink constellation satellites; to see 60 objects at a time moving across the sky was startling. For astronomers the bright streak of a satellite running…

AUGUST HIGHLIGHTS How to make the Universe from scratch Interview: particle physicist Dr Harry Cliff traces the building blocks of the cosmos back to the Big Bang. Watch The Sky at Night: Space Boom Britain Maggie and Chris reveal how the British space industry plays a vital role in humanity’s exploration of the Universe. Astrophoto gallery: Solar eclipse special View our pick of the best images of the 10 June partial solar eclipse sent to us by BBC Sky at Night Magazine readers. The Virtual Planetarium Pete Lawrence and Paul Abel guide us through the best sights to see in the night sky this month.…

The Sky at Night TV show, past, present and future The Sky At Night may not boast the glitz and glamour of other television shows, but to me it is and has always been essential viewing. Ignited, as I was, with a passion for the heavens at an early age, it was Sir Patrick Moore – through the show he was so synonymous with for 55 years and his many (so many!) books – that would further inspire me to take my passion for astronomy as far as I could. I have been incredibly fortunate to still have some small involvement in the subject by working on this, most special, of programmes from time to time over the years. It was therefore a real privilege to be asked to make…

I had been looking forward to the solar eclipse on 10 June, even though I knew Id only see a partial eclipse from my location – we just needed the weather to be kind to us. So naturally I awoke to a very grey Sheffield morning. It wasn’t just cloudy; it was a grey blanket. I couldn’t even see where the Sun should be, so I would have to trust my mount to find it for me. I set up my Lunt LS60THa/B600 solar scope and Canon EOS 1100D DSLR on a Sky-Watcher EQ5 Pro mount just in case, but there was no improvement at the time of the first contact. Around 10:45am, however, I noticed the sky was brighter and went out to have a look. There were a…

The short, summer nights are a good time to trawl through space programmes in the BBC archive. Stretching back over decades, there are classic moments aplenty, from James Burke’s live reaction to Apollo 13’s safe return, to a vintage Sky at Night episode where Sir Patrick Moore met Pluto’s discoverer Clyde Tombaugh. Horizon gives us 1966’s ‘Man in Space’ on the everyday life of NASA’s astronauts, a 1981-era ‘Race to Ruin’ on space weaponry, and an interview with cosmonaut Valentina Tereshkova. A 1969 Panorama looks at Moon mission costs, while a 1987 Tomorrow’s World covers the ‘Race to Mars’. bbc.co.uk/archive/collections…

If you get into watching the Perseids this month, why not keep a methodical record of the meteors you see over each hour. This will make an interesting keep-sake of a successful night of observing and can aid scientists with their work too. Records of visual meteor observations are still used today by researchers as a way to gather information about the meteoroid streams left by comets and asteroids. Pictures, video and eyewitness reports can also be a key source of useful data, particularly when it comes to bright meteors known as fireballs, as these can sometimes drop meteorites to the ground. As these started life as fragments of other bodies in the Solar System, such as asteroids, this material can be of scientific importance and there are teams worldwide…

TEMPO, NASA & Smithsonian Astrophysical Observatory The Tropospheric Emissions: Monitoring of Pollution (TEMPO) instrument will fly aboard a commercial satellite and measure the daily variations in air quality over North America. Expected to launch in 2022, it will assess concentrations of ozone, nitrogen dioxide, sulphur dioxide and other chemicals from a geostationary orbit to track emissions and improve air-quality forecasts. GRACE-FO, NASA & German Research Centre for Geosciences The Gravity Recovery and Climate Experiment Follow-On mission is a pair of satellites launched in 2018 to monitor Earth’s water. GRACE-FO picks up where GRACE left off, providing an indication of climate variability by measuring small changes in the planet’s gravity field that correspond to the amount of water in lakes, rivers, oceans, ice sheets and the ground. Copernicus Sentinel fleet, ESA…

Jupiter Best time to see: 19 August, 01:22 BST (00:22 UT) Altitude: 23.5° Location: Capricornus Direction: South Features: Detailed atmosphere, Great Red Spot, moons Recommended equipment: 75mm or larger Jupiter reaches opposition on 19 August, the planet managing to attain a peak altitude of 23.5° in true darkness, due south, at 01:22 BST (00:22 UT). Full Moon, technically the Moon at opposition, appears 6.3° south-southwest of Jupiter on the night of 22 August. Opposition describes a position in the opposite part of the sky to the Sun. At such times, planets appear brighter and larger than at other, non-opposition, times. In Jupiter’s case, at opposition it shines at mag. –2.9 and through the eyepiece of a telescope has an apparent diameter of 49 arcseconds, large enough to present some impressive…

Minor planet 89 Julia reaches opposition in Aquarius this month, shining at mag. +9.0 near the Water Jar asterism. The Water Jar, or ‘Steering Wheel’, is formed of four similar brightness stars in the northern regions of Aquarius. It sits south of the triangle that forms the upside-down head of Pegasus and to the west of the faint Circlet asterism in Pisces. Its four stars are mag. +4.3 Zeta (ζ) Aquarii in the centre, mag. +4.4 to +4.7 variable star Pi (π) Aquarii to the north, mag. +4.0 Eta (η) Aquarii to the east and mag. +3.8 Gamma (γ) Aquarii to the west. The asterism lies 5° east of mag. +2.9 Sadalmelik (Alpha (α) Aquarii) and is quite easy to locate. At the start of August, 89 Julia is located…

THE GREAT BLUE SPOT When the Juno team put together their map of the magnetic field, they discovered a dark spot of highly concentrated magnetism near the equator. Though invisible to the naked eye, the patch appeared blue in their map’s colour scheme – hence its name. THE STORMS OF THE POLES Juno was able to get the first ever look at Jupiter’s poles from above, finding they were swarmed by storms. The north pole has a single central storm, surrounded by eight companions, ranging from 4,000km to 7,000km in size, which have remained stable throughout Juno’s mission. JUPITER HAS WATER Juno found that Jupiter has three times more water than the Sun, putting to bed a decades-old mystery. In 1995 the Galileo spacecraft’s measurements indicated that the planet was…

Using a telescope and your eyes, intensity estimates can be made of Saturn. You’ll need a planetary blank to show the correct outline of the planet for the observing date. Win Jupos can generate blanks by selecting Saturn from the ‘Program’ > ‘Celestial body…’ option, before choosing ‘Tools > Ephemerides…’ and going to the ‘Graphics’ tab. Make sure the date is set correctly and turn off any textures, etc, to show a planetary outline which can be printed. At the eyepiece, the intensity estimate is done by dividing the planet into areas of equal brightness. A numeric scale of 0 to 10 is then used to annotate each area according to its brightness, 0 being bright, 10 dark. Intermediate, decimal values may be used if required. In order to calibrate…

Rising over Lake Michigan Chirag Bachani, Evanston, Illinois Chirag says: “After months of planning and waking up early to practise sunrise shots, my friend Jesus Hernandez and I watched in awe as the crescent Sun rose over the water’s edge. As the Sun crept higher in the sky, I dimmed my exposure and captured this image of the Sun’s bottom edge lifting off Lake Michigan.” Equipment: Olympus OM-D EM10 II mirrorless camera, Olympus M.Zuiko Digital ED 75–300mm lens Exposure: ISO 1000 f/6.7, 1/800” Software: Lightroom Chirag’s top tips: “The most important part of capturing a solar eclipse is preparation. Use an app such as PhotoPills to determine the location and timing of the eclipse. Go on location several days in advance and practise taking images of the Sun. Experiment with…

Affinity Photo is the image-processing package in Serif’s Affinity suite of products, gaining popularity with many professional photographers who are discovering just how powerful the software is. The program is constantly being updated, with some extremely useful astrophotography tools being introduced earlier this year. The most notable are tools for star alignment, and background and gradient removal, as well as Affinity’s ‘Astrophotography Stack Persona’. Here, we take a look at these and other features that are useful for astrophoto processing. These new astrophotography tools will certainly turn the heads of many astro imagers who are wanting a single package that does everything at an affordable price. We particularly liked Affinity Photo’s single one-off payment user licence model, as it means you’re not locked into making long-term monthly payments. The only…

Disc-less dwarfs The dusty ring of debris found around white dwarf stars only appears after 10–20 million years, according to a recent study. When the dwarfs first appear, after a Sun-like star goes through its red giant phase, they are so hot they vaporise the surrounding debris, preventing a disc from forming. 500 radio bursts The Canadian Hydrogen Intensity Mapping Experiment (CHIME) detected 535 fast radio bursts in its first year of operations. Before CHIME, only 140 of the mysterious bursts – which last only a fraction of a second – had been detected since their discovery in 2007. Colossal comet An impressive 100km-wide comet, believed to have originated in the distant Oort cloud, was spotted creeping into the inner Solar System in June. Comet C/2014 UN271 is currently 20…

The amateur astronomer’s forum An astronomer’s best friend? Jonathan Powell weighs up the stargazing companionship of cats and dogs Some of us revel in the solitude of darkness and the accompanying silence when observing the night sky, as we connect in our own special way with the Universe. But, aside from the odd twitching curtain or the unwelcome dazzling headlights of a neighbour returning home late, we astronomers know we’re not the only ones enjoying the tranquillity. With dark adaptation sharpening night vision and a more finely tuned sense of hearing in the silence, one becomes aware of nature’s nightlife around us, and the owls, bats, rodents and foxes who are using the hours of darkness to conduct their nocturnal business. While wild animals aren’t overly bothered with what we…

1. The basic kit A basic DSLR or bridge camera – with a standard, wide, kit lens – and a solid photo tripod are ideal for simple meteor photography. Focus the lens by pointing at a bright star, zooming in on the Live View if you have it, and adjusting the focus ring until the star appears as small as possible. Then, set your ISO setting to a relatively high value, point your camera skyward and start taking 10 to 30 second-long exposures. 2. Take as many images as you can It’s really luck if a Perseid passes through your camera’s field of view, so you’ll want to take as many images as you can to have the best chance. This can be achieved by setting your camera to continuous…

“Satellite observations provide a much more consistent view of emissions globally than we would get from individual approaches.”– Dr Richard Engelen Something big happened in 2020. According to the Global Carbon Project, carbon dioxide (CO2) emissions declined by 2.4bn tonnes – the biggest drop ever recorded. It is a faint silver lining to a year of COVID-19 lockdowns, and a distraction from the longer-term trend – in 2019 CO2 emissions hit a record high (36.8bn tonnes). Now, as restrictions ease thanks to vaccination programmes, CO2 emissions are returning to pre-pandemic levels. Nevertheless, 2021 could be a big year for cutting CO2. After taking office in January, President Joe Biden reinstated America’s commitment to the Paris Agreement, an international treaty on climate change. In April, Prime Minister Boris Johnson set new,…

Delphinus is a small but very identified constellation representing the head and neck of a bottlenose dolphin. It lies 12° to the east and slightly north of the bright star Altair (Alpha (α) Aquilae), which marks the bottom vertex of the giant Summer Triangle asterism, which is well placed at this time of year. Delphinus resembles a diamond shape with a tail. The two stars on the western side of the diamond, Alpha (α) and Beta (β) Delphini, have the unusual names of Rotanev and Sualocin, more of which to follow. Sualocin is a binary star with five additional companions which are most-likely just line-of-sight acquaintances. The binary star consists of Alpha Delphini Aa (Sualocin) and Alpha Delphini Ab. The pair appear close with a separation of just 0.2 arcseconds…

The liquid water oceans of Jupiter’s icy moons have long held a fascination for planetary scientists, partly for what they can teach us about water in our Solar System and partly because of the tantalising possibility that they might provide havens for life. Now three planned missions will turn their focus on these icy worlds. First to launch in June 2022 will be the European Space Agency’s (ESA’s) Jupiter Icy Moons Explorer (JUICE) looking at Jupiter’s moons Ganymede, Callisto and Europa. After arriving at the gas giant in 2029, JUICE will spend the first few years orbiting Jupiter, performing flybys of the moons to map out their surfaces visually, while using radar to peer beneath. Finally, in 2032, JUICE will start orbiting Ganymede, the largest moon in the Solar System.…

Filters can be used to enhance both visual and imaging sessions. The Wratten (W) scheme is commonly employed for visual planetary observation, with filters normally identified by ‘W’, followed by a number and sometimes a letter. Visually, a light blue filter (W38A or W80A) enhances contrast within brighter zones and draws out detail in atmospheric clouds. Light green (W57) and blue (W47) helps to darken brown-hued belts. A W57 light green or a magenta (W30) filter also helps highlight Saturn’s rings. Using a W30 filter, meanwhile, will brighten white ovals in Jupiter’s atmosphere. When imaging, mono camera setups work best for filter work. Full colour images are made by imaging through red, green and blue imaging filters and combining the results. Infrared (IR) pass filters produce high-contrast results, great for…

Noctilucent clouds (NLCs) are the highest clouds in the atmosphere and we can see them around astronomical twilight in a summer’s night sky. The name comes from Latin, meaning ‘night-shining clouds’, and they occur when the Sun is below the horizon and the clouds are still in sunlight. Although no one as yet fully understands why, this appears to be a relatively new phenomenon first seen in 1885 and with an increased frequency in recent years. First sightings While these clouds can be a spectacular sight, curiously no one appears to have recorded observing them before 1885. Two years earlier, in 1883 the volcano Krakatoa erupted, destroying land, creating tsunamis and causing around 36,000 deaths. The after-effects of the eruption were felt for years and included vivid red sunsets, which…

Clear skies may produce plenty of bright Perseid trails, but capturing one on camera isn’t easy. This month we’re looking at how to record meteor trails using a high frame rate camera, the sort normally used to image planets. These cameras have good sensitivity and the option to take really short exposures. However, we’re ignoring this and extending their capability to record wide-angle shots of the stars using longer than normal exposures, like we would do with a DSLR. There are lots of planetary cameras on the market and many can be used for this task. A lens will be needed and these can be obtained through many online sources. A fast C-mount CCTV lens is required, along with a T-thread to C-mount adaptor (the T-thread being the thread in…

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1 Apollo flight plan poster Price From £42 • Supplier Astrography https://astrography.com Blend science with art with this specially designed print showing the flightpath of the Apollo missions, including detailed notes of each stage. Available both as a poster and a high-quality, fade-resistant print. 2 NASA Solar System construction set Price £14.99 • Supplier Firebox • https://firebox.com Create your very own Solar System with this kit. Paint your own planets, mount them up and then rotate them around the light-up Sun. It’s a great way to learn about the planets and it makes a unique desk toy. 3 Women’s Charna insulated diamond quilted bodywarmer Price £29.95 • Supplier Regatta • www.regatta.com Quilted with Thermoguard insulation, this vest helps keep you warm without adding bulk so you can layer up on…