Tabla de contenidos para August 2025 en BBC Sky at Night

Find it at www.skyatnightmagazine.com/bonus-content AUGUST HIGHLIGHTS Interview: our Galaxy's near-miss Astronomer Alis Deason reveals why our Milky Way may not collide with the Andromeda Galaxy after all. Your best images of the Universe Our extended gallery featuring the best astro images sent to us by BBC Sky at Night Magazine readers. Track and record sunpots safely Download a solar ruler to help you measure sunspots regions lying close to the solar limb. See page 74 for details. The Virtual Planetarium Pete Lawrence and Paul Abel guide us through the best sights to see in the night sky this month.…

Astronomers have detected two puzzling exoplanets orbiting a distant, Sun-like star known as YSES-1. The observations revealed sand-like silicate clouds around one and an unexpected disc around the other. The planets, YSES-1c and YSES-1b, are several times larger than Jupiter and are in a distant orbit from their host star. Because they are relatively young, around 16.7 million years old, they are still hot and produce thermal infrared radiation. To spot them, an international team used JWST’s infrared-sensitive instruments to obtain spectra and determine the composition of their atmospheres. “When we looked at the smaller, farther-out companion, YSES-1c, we found the tell-tale signature of silicate clouds,” says Dr Evert Nasedkin, a member of the team based at Trinity College Dublin. “This is the strongest silicate absorption feature observed in an…

Until now, every image of our Sun has been taken from around its equator. Now, ESA’s Solar Orbiter spacecraft has pulled off a solar first and imaged the Sun from its south pole. These are humanity’s first-ever views of our star from this angle. “The Sun is our nearest star, giver of life and potential disruptor of modern space and ground power systems, so it is imperative that we understand how it works and learn to predict its behaviour. These new, unique views from our Solar Orbiter mission are the beginning of a new era of solar science,” says Professor Carole Mundell, ESA’s director of science. Analysing the data taken from all three of Solar Orbiter’s imaging instruments will tell scientists about material moving in the Sun’s outer layers. As…

I find it hard to believe it’s been 25 years since I appeared on The Sky at Night for the first time. A scared student in a new suit, I’d been invited by Patrick to discuss viewers’ questions, which ranged from ‘Why are there seasons?’ to ‘What, precisely, is dark energy?’. While some of the questions are the same today, everything else is different. For starters, the show back then was filmed in the corner of a vast studio at BBC Television Centre in west London, with camera operators gliding around and instructions from the producers in our ears. As the cameras got smaller, we moved to Patrick’s home, Farthings, and for many years we’ve travelled the world (well, mostly the UK). But what has changed in astronomy in 25…

There’s a meme that’s been floating around on social media recently, offering encouragement to turn our everyday perspective upside down: “In the entire Universe, wood is rarer and more valuable than diamonds.” While diamonds are surprisingly common in the Universe – being made from (very abundant) carbon crystallised in the high pressures of asteroid collisions and gas giant atmospheres – wood is stupendously rare. It requires life and a whole succession of evolutionary inventions, like DNA and photosynthesis – not to mention the presence of liquid water and a stable atmosphere. As far as we know, these conditions exist only on Earth. And if wood is rare, what about an intelligent, self-aware, communicative and inquisitive being, such as… you? In 1961, Frank Drake came up with an equation to calculate…

1. Lowell's canals Percival Lowell and others interpreted strange linear markings on Mars as canals engineered by sentient Martians. Future observations disproved this as an optical illusion, but author CS Lewis said the canals became “part of the popular tradition”. Mariner 4’s fly-by in 1965 conclusively disproved their existence. 2. War of the Worlds HG Wells’s 1898 War of the Worlds presented Martians with an inhuman appearance. Inspired by 19th-century British colonialism and its devastating effect upon Aboriginal Tasmanians, Wells inverted the idea of aliens from beneficent beings of higher intelligence into fearsome, warlike creatures. 3. Orson Welles's radio broadcast In 1938, Orson Welles narrated an adaptation of War of the Worlds for CBS. Presented as a simulated radio broadcast, with newsflashes and eyewitness accounts, its description of a Martian…

PICK OF THE MONTH Uranus Best time to see: 31 August, 04:00 BST (03:00 UT) Altitude: 48° Location: Taurus Direction: Southeast Features: Colour, subtle atmospheric banding, moons Recommended equipment: 200mm or larger It’s surprising how rapidly darkness expands in August, which is perfect timing for viewing the planet Uranus, as by the end of the month it’s able to reach a decent altitude above the southeast horizon before the onset of dawn. On 1 August, morning twilight truncates the observing window at around 02:20 BST (01:20 UT), this distant world only achieving a peak altitude of around 16° on this date. For many years, Uranus has been in stellar limbo on the Aries–Taurus border. While not particularly difficult to track down, it has lacked bright guiding stars over this period – something that may have…

1. The Perseus Double Cluster A third of the way from mag. +3.8 Miram (Eta (h) Persei) to mag. +2.6 Ruchbah (Delta (d) Cassiopeiae), you will find a close pair of open clusters. The pair may be visible to your naked eye, but large binoculars will help you to experience the 3D illusion that makes it so attractive. Those stars are intrinsically far brighter than our Sun, which, if it were at that distance, with these binoculars would be too faint to be seen! □ SEEN IT 2. The Muscleman Cluster From the part of the Double Cluster that is nearest Cassiopeia, there is a 2° curved chain of eighth-magnitude stars leading to the north. They guide you to Stock 2, the Muscleman Cluster. You will recognise it from the…

We were at latitude 71º north, in the Barents Sea off Norway, when we got our first “Wow!” moment. No geomagnetic storm had been predicted, but there, around the stars of Cassiopeia, a greenish curtain was weaving across the sky. A sea of smartphones was lifted and seconds later there were beaming smiles all round. It hadn’t begun like this. The Hurtigruten cruise ship MS Nordkapp had travelled under cloudy skies for several days as it plied the Norwegian coast on its regular 11-night route from Bergen to Kirkenes and back. It called in at remote fishing villages, delivering parcels and picking up supplies, and occasionally dropping off passengers to go dog sledding or snowmobiling, or attend a Viking-themed dinner. Settling into cruise life The first few days were taken…

We’ve all seen pictures of comets, their dusty tails stretching across the sky. Those tails form because comets are made of dust and ice; when they get near the Sun, the ice melts, releasing some of the dust into space. Over time, this creates a dusty trail along the comet’s path around the Sun. When Earth passes through that trail, some of the dust enters our atmosphere and burns up, producing a meteor shower. For example, we pass though dust from Halley’s Comet twice each year, giving rise to the Eta Aquariids in May and the Orionids in October. Most of the well-known showers are caused by comet dust, but there’s one exception: the Geminids. Their source is believed to be asteroid 3200 Phaethon, rather than a comet. How can…

CAUTION Never observe or image the Sun with the naked eye or any unfiltered optical instrument The Sun’s surface often looks speckled with darker regions. These are sunspots – cooler patches that form as a result of the Sun’s complex magnetic field preventing heat from reaching localised areas of the photosphere. How many you’ll see varies during the 11-year solar cycle, with greater numbers during solar maximum – which we’re in right now. Humans have been observing sunspots for centuries, but we have only tracked them in detail since the telescope was invented. Originally, this meant projecting through the telescope onto a piece of white card and sketching the result. These days, observing and photographing the Sun is done either with a certified solar filter on the front of a…

PHOTO OF THE MONTH The Flaming Star Nebula Prabhu, Emirates Astronomical Observatory, Abu Dhabi, UAE, November 2022, April 2023 and October 2023 Prabhu says: “This was a challenging target. I gathered enough broadband and narrowband data to highlight both the hydrogen glow and the blue reflection. Processing was tricky, but I’m happy with how it turned out.” Equipment: ZWO ASI294MM Pro camera, Sky-Watcher Esprit 80 ED refractor, iOptron CEM70G mount, Sky-Watcher AZ-EQ6 mount Exposure: L 25× 300”, 71× 180”, R 24× 300”, G 24× 300”, B 24× 300”, total 23h 48’ Software: PixInsight Prabhu’s top tips: “For nebulae, collect enough narrowband and broadband data to ease post-processing. Avoid oversaturating stars in broadband, which can cause haloes or rainbow artefacts. There’s no fixed Ha:L:RGB ratio, but 40:40:20 works well. Be patient,…

VICTOR M BLANCO 4-METER TELESCOPE, 10 JUNE 2025 The Chamaeleon I dark cloud is one of the closest star-forming regions to Earth. It sits at the surface of the Local Bubble – the sparsely populated region of the Milky Way’s Orion arm through which our Solar System has been travelling for the past five to 10 million years – and, together with the Chamaeleon II and Chamaeleon III dark clouds, forms part of a larger structure, the Chamaeleon Complex. As well as containing three reflection nebulae, the region is thought to be home to 200–300 stars with a median age of just one or two million years. Astronomers say the birth of our own Sun and the Solar System planets can be traced back to huge clouds of gas and…

The Hakuto-R Mission 2, named Resilience, has failed to land near the centre of the Moon’s Mare Frigoris (Sea of Cold) after its laser rangefinder malfunctioned during descent. The failure marks another blow for Japanese private robotic exploration company ispace, whose earlier mission to the Moon also crash landed in 2023. Resilience launched in January from Kennedy Space Centre, Florida, aboard a SpaceX Falcon 9 rocket. It travelled for four months before entering a lunar orbit on 7 May. The Japanese firm lost communications with the craft as it began its descent phase. “ispace will not let this be a setback. We will not stop here, but as determined pioneers of the cislunar economy, we will strive to regain the trust of all stakeholders and embark on the next mission,”…

The Cosmic Evolution Survey (COSMOS) has released an interactive version of the largestever map of the Universe. In a triumph for democratic science, the multinational collaboration took data from the JWST to compile a catalogue of over 800,000 galaxies spanning all of cosmic time, corresponding to over 255 hours of astronomical observation. The map, a composite image across 0.54 square degrees of sky, reaches back into the early Universe, with data going as far back as 13.5 billion years, around 98 per cent of all cosmic time. The goal was to reconstruct the deep field of space, examining the composition of the far, faint Universe on an unprecedented scale. Caitlin Casey, professor at the University of California Santa Barbara and one of the leaders of the COSMOS-Web project, compares it…

The Moon has a diameter of around a quarter that of Earth and travels around our planet in a circular orbit roughly every 27 days. But Earth also possesses a number of tiny co-orbital bodies – objects orbiting the Sun and so not true satellites of Earth, but which are influenced by our planet’s gravity and shadow our planet closely. These companions fall into several categories: objects on a ‘horseshoe’ or ‘tadpole’ orbit are repeatedly accelerated and decelerated by Earth’s gravity; ‘quasi-satellites’ follow a one-year elliptical orbit around the Sun such that they appear to be on a wide, retrograde orbit around Earth. There are four known bodies on horseshoe orbits of Earth, two in tadpole motion, five quasi-satellites, and four objects flip-flopping between quasi-satellite and horseshoe. The orbital dynamics…

The prospect of life on Mars – Earth’s planetary next-door neighbour, an alien world that betrays tantalising hints of a watery past – has bewitched humanity for centuries. From the ‘canals’ seen by astronomer Percival Lowell, and HG Wells’s fire-spewing tripods, to David Bowie’s glam-rock croons about a girl with mousy hair, life on Mars has captured our imagination as a literal and metaphorical trope. At first glance, the contrast between the iridescent blues, greens and tans of Earth – awash with water, teeming with life – and the barren, subfreezing, radiation-drenched Mars could hardly be more stark. Half the size of Earth and 11 per cent as massive, Mars’s orbit around the Sun takes it as near to us as 56 million km (35 million miles) and as far…

Scorpius is one of the most distinctive and easily recognised constellations in the night sky, and has captivated the imaginations of stargazers for millennia. It’s renowned not only for its red, bright heart, the star Antares, but also for its ancient mythological roots, stunning deep-sky objects and a rather contentious historical relationship with its neighbour Libra. It’s a constellation steeped in myth, most notably Greek mythology, representing the scorpion sent by the Earth goddess Gaia (or sometimes Artemis or Hera, depending on which version you follow) to kill the great hunter Orion. According to the story, Orion boasted that he would slay every animal on Earth, angering the gods. To punish his conceit, a giant scorpion was sent to confront him and sting the hunter to death. The gods placed…

Mercury Best time to see: 19 August, 40 minutes before sunrise Altitude: 8° (low) Location: Cancer Direction: East-northeast Mercury reaches inferior conjunction on 1 August and so will be difficult to see until around 19 August, when it emerges from the Sun’s glare into the morning sky. On the 19th, it rises a little under 2 hours before the Sun. On this date, it shines at mag. +0.1 and is 2.5° south of the Beehive Cluster, M44, but the morning twilight will mask the cluster stars. A slender 4%-lit waning crescent Moon joins the scene on 21 August, 7.6° northwest of mag. –0.2 Mercury. On 31 August, Mercury rises 1 hour 15 minutes before the Sun and shines at mag. –1.1. Venus Best time to see: 12 August, 90 minutes before sunrise Altitude: 13° Location:…

Minor planet 2 Pallas reaches opposition on 10 August, when it can be found among the stars of Delphinus, the Dolphin. The pattern of stars that forms Delphinus is distinctive, resembling a small diamond with a tail (the diamond is the dolphin’s nose, the tail the start of its neck). A familiar highlight of summer skies, it acts as an excellent guide for locating Pallas at the start of the month. Pallas arcs from a position near Sualocin (Alpha (α) Delphini) on 1 August, away to the southwest over the course of August to end up near the Delphinus–Aquila border. Conveniently, Pallas remains within the confines of Delphinus all month and maintains a constant mag. +9.4. Although too faint for average binoculars, a small telescope will pick it out easily.…

Capturing the aurora has become far simpler, especially with modern smartphone cameras, which are now well-suited for shooting the Northern Lights from a moving ship. These devices can effectively handle short exposures, making them ideal for this scenario, and they can produce impressive videos of the aurora that were once only possible with expensive cameras. They’re so good that you can also use them to check that what you’re seeing is actually the aurora. The key to success lies in the smartphone’s night mode. Newer smartphones have significantly enhanced low-light capabilities, with night mode on the iPhone allowing for long exposures anywhere from three to 10 seconds. Android users can experiment with Pro mode, which gives manual control over settings like shutter speed and ISO. Increasing the ISO to 6400…

We all love watching meteor showers like the Perseids in August. These dramatic events are one of the easiest astronomical events to observe because they’re regular, you don’t need to travel to see them and they require nothing more than your own two eyes – and a comfortable chair! However, many amateur astronomers are now taking their sky watching up a level by recording meteors during showers and reporting their observations to organisations like the British Astronomical Association (BAA), Global Meteor Network (GMN) and the UK Meteor Network (UKMON). So, why are they doing this? Collecting meteor data is a great way to get involved in science that has realworld implications. Data from amateurs has helped us protect spacecraft and astronauts, locate meteorites, explore the origins of life on our…

Our eyes paint such vivid portraits of the world around us that it’s easy to forget how much of our surroundings go unseen. Wi-Fi signals pinging this way and that, subatomic particles and radiation zipping about. And, if astronomers are to be believed, there’s another invisible interloper to throw into the mix: dark matter. A cosmic glue thought to help bind the Universe together, dark matter is so prevalent that about a milligram (3.5oz) will pass through your body throughout your life. But where did this notion of ‘dark matter’ come from? Its story starts in the 1930s. Astronomer Fritz Zwicky was measuring the speeds of galaxies within a big group called the Coma Cluster. He found many were moving so fast that he would have expected them to break…

Scientists from the University of Hawaii’s Institute for Astronomy (IfA) have discovered the most energetic cosmic explosions since the Big Bang. Extreme nuclear transients (ENTs) occur when massive stars several times larger than our Sun are torn apart by supermassive black holes. ENTs shine with intense luminosity, much brighter than supernovae, which originate from the violent death of massive stars. One ENT observed by the team at IfA emitted over 25 times more energy than the most energetic supernovae known, radiating the energy of around 100 Suns in a single year. “We’ve observed stars getting ripped apart as tidal disruption events for over a decade, but these ENTs are different beasts, reaching brightnesses nearly 10 times more than what we typically see,” said Jason Hinkle, the researcher at IfA who…

One of the JWST’s superpowers is its ability to investigate the cosmic dawn, the first few hundred million years after the Big Bang. The telescope has once again lived up to its reputation, spotting light from a galaxy which existed only 280 million years after the Big Bang, the most distant ever detected. Known as MoM-z14, it displaces the previous record holder, JADES-GS-z14-0, which existed 300 million years after the Big Bang. When looking for these galaxies, JWST investigates objects with high redshift. Redshift, often denoted by z, is where the wavelength of light becomes stretched as it travels to us through expanding space. The redder the light, the higher the redshift and the more distant the object. You may have heard of the phenomenon in the case of sound;…

Email us at inbox@skyatnightmagazine.com I’ve never considered myself artistic, but I recently began experimenting with collages. Before I recycle my monthly issue of BBC Sky at Night Magazine, I take clippings of the most eye-catching images, illustrations and titles. This is my favourite collage so far (right): cuttings from your magazine about Mars’s seemingly arid surface, contrasted with text and illustrations from an outdated astronomy encyclopedia speculating on the Red Planet’s agriculture, giving a fantastical sense of humanity showing up late to the Martian party. Not only does this highlight how far our knowledge has come, but it reminds us that we still have so much to learn – which makes me excited always for the future. Thank you for making your magazines so visually stunning, as well as informative;…

Measuring 154km (96 miles) wide, Gale crater, which NASA’s Curiosity rover has been exploring since 2012, may have been a freshwater lake with vigorously flowing water 3.8 billion years ago. Its environmental conditions included neutral pH levels, low salinity and minerals usable by microorganisms. Since 2021, Perseverance rover has investigated Jezero crater, a clay-rich area with an ancient lake up to 250 metres (820ft) deep. Conditions recorded at Jezero’s Wildcat Ridge show it might once have been habitable. In 2024, Perseverance found leopard-like ‘spots’ on a reddish rock called Cheyava Falls that may have hosted microbial life. The 4,000km (2,500-mile) canyon Valles Marineris may have contained a number of ancient lakes, with minerals present that only form in the presence of water. Some lakes could have been 0.8km (0.5 miles)…

DON’T MISS Mercury, Venus and Jupiter BEST TIME TO SEE: From 03:30 BST (02:30 UT) all month. Closest approach on 12 August Venus is the brightest planet that can be seen from Earth. At its peak brightness, when 22% illuminated, Venus approaches mag. –5 – that’s so bright that it can cast shadows, if conditions allow. Jupiter is bright too, able to reach mag. –2.94 under optimum conditions (coincidentally, that’s the same maximum brightness as Mars). Mercury isn’t far behind, able to attain a peak magnitude of –2.48. Of course, catching all four near one another at peak brightness can’t actually happen, as Jupiter and Mars need to be opposite the Sun, a position that Mercury and Venus can never attain. That’s not to say that a meeting between some…

SS Cygni is a variable star in the northeast corner of Cygnus, the Swan. This is a cataclysmic variable consisting of two stars in close orbit around one another. One is a red dwarf, the other a white dwarf. When we say close, this isn’t an exaggeration: they’re just 160,000km or less apart. Being this close, the massively dense white dwarf pulls material from the red dwarf, forming an accretion disc around the white dwarf, with matter spiralling inwards. Some of this hydrogen-rich material undergoes a runaway fusion reaction that raises the brightness of the system. From Earth, SS Cygni typically presents itself as a 12th-magnitude star, but every 7–8 weeks it undergoes an outburst due to the fusion process, rising to eighth magnitude for 1–2 days. This makes SS…

Aurora forecasting can be done with precision – if you know how. However, the Kp index – one of the main metrics for predicting aurorae – is of limited use if you’re already in the auroral oval. The Kp index, measured on a scale from 0 to 9, refers to the intensity of any aurora and how far south the auroral oval might stretch. That’s useful in the UK and North America, but not in more northerly regions, where aurorae can and do appear during Kp 0 conditions. There, it’s more helpful to watch data from the DSCOVR and ACE satellites, which give about 40–60 minutes’ warning of what the solar wind is doing. Available on apps like Glendale Aurora Alerts (www.aurora-alerts.uk), the key real-time data to watch is the…

If you want to step up from visual observing, the simplest way is with the Raspberry Pi Meteor Software (RMS). RMS is a free, open-source program that runs on a Raspberry Pi or Linux PC and uses a cheap security camera to take video of the night sky. It is almost fully automated and will run every night without human intervention. The cameras have a very wide field of view – about 90° by 45° – and are very sensitive in low light, which makes them ideal for meteor hunting as they can pick up meteors up to five times fainter than the human eye can detect. The software can be downloaded via the link below, where you’ll also find instructions on how to build the camera and the other…

What makes your team’s discovery on Mars so exciting? We found large organic molecules composed of 10, 11 and 12 atoms of carbon. These long, chain-shaped molecules – called alkanes – are very fragile. They’re much more fragile than the ring-shaped (or ‘aromatic’) molecules made of carbon that we detected previously. What this shows is that these long-chain molecules can be preserved over geological periods of time. They were found on rocks that are 3.7 billion years old, which means they were deposited 3.7 billion years ago and preserved until today. This has huge implications for the search for life on Mars, because we believe that, if life ever existed on Mars, it was around the same time that these molecules were deposited. What do we mean by ‘organic’ molecules?…