Indholdsfortegnelse for June 2025 i BBC Sky at Night

Black holes are often thought to be hungry giants eating as much matter as they can. But one black hole has left astronomers puzzled. After a nap that lasted decades, Ansky, the black hole at the centre of the SDSS1335+0728 galaxy, has burst back to life in dizzying style. Astronomers first became aware of Ansky’s awakening in 2019, when they caught optical and X-ray outbursts from the black hole. These burps are called quasi-periodic eruptions or QPEs. Supermassive black holes can be active, consuming the gas around them, or quiet, and they can transition between the two states. But this is the first time that scientists have captured a black hole ‘waking up’ in real time. Observing QPEs is not unusual, but the size and strength of the explosions from…

What’s the first thing that comes to mind when you think of Mars? I ask because that dusty red rock has been a documented feature of human culture for at least four millennia, so I think most people will have a ‘thing’ they immediately associate with the planet. For me, it’s Jeff Wayne’s synthy masterpiece adaptation of HG Wells’s The War of the Worlds. Specifically, the first track (although all of it is excellent). More specifically: “but still… they come.” If you’ve never heard it, pause your reading here and go listen; I guarantee you nine minutes of giddy goosebumps. Our crimson planetary sibling loves a bit of media attention, both factual and fictional. Mars Attacks!? Fictional. Interesting black specks on rocks that could be evidence of long-ago microbial activity?…

I’ve spent a lot of time indoors in my life. I’ve been a professional astronomer and the job is, surprisingly, mostly desk-bound – data crunching, reading the literature and writing papers. Even an amateur stargazer probably spends more hours at the computer processing images and preparing their tech than outside with their telescope. These days I’m doing more writing, which I also tend to do indoors. And if I spend too long inside, I start to feel stale. I find myself shrinking away from the world, and the longer it goes on the more I want to retreat. It takes effort sometimes to get outdoors. I don’t mean just down to the shops, but really out in nature. But when I do, the stale feeling is blown away and I…

The 2003 storms sent ISS astronauts Michael Foale and Alexander Kaleri running – or floating – for cover. They sheltered in the Zvezda service module, the most shielded location aboard the ISS, cutting their radiation exposure by 50 per cent. The ISS orbits within Earth’s magnetosphere and this, along with the shielding provided by the station, is enough to keep astronauts safe when the weather outside is lousy. For explorers heading further afield, such as the Artemis astronauts returning to the Moon, or future Mars colonists, it’s a different story. In August 1972, between Apollo 16 and 17, there were a series of powerful solar storms that would have given the astronauts radiation sickness had they been in space at the time. The situation wouldn’t have been much better had…

DON'T MISS Noctilucent clouds for 2025 BEST TIME TO SEE: All month For those of us in the Northern Hemisphere, the lack of true darkness in the middle of the year doesn’t make astronomy that easy to do. The planets are good at cutting through slightly brighter skies, but they aren’t currently well placed. On top of that, in the weeks around the solstice, the period of night is fleetingly short. Fortunately, there’s an upside to this, as the period between late May and early August is when noctilucent clouds (NLCs) may be seen. These high-altitude ice-sheet clouds form at a height of around 82km, but their presence isn’t guaranteed. They become visible during these months because this is when the region within the mesosphere in which they occur dips…

While the June sky never gets properly dark, it does mean brighter stars get a chance to stand out unencumbered by their fainter neighbours. This is certainly the case with the two primary stars of Libra, Zubenelgenubi (Alpha (α) Librae) and Zubeneschemali (Beta (β) Librae), which pass low across the southern horizon at this time of year. ‘Zuben’ comes from the Arabic for claw, ‘al-zubānā’, and the two stars translate as ‘northern claw’ (Zubeneschamali) and ‘southern claw’ (Zubenelgenubi). Libra represents the scales, an object not in need of too many claws! But both stars, located northwest of Antares (Alpha (α) Scorpii), once belonged to Scorpius. Zubenelgenubi is a double star, Alpha1(α1) and Alpha2(α2) Librae; the name Zubenelgenubi is attached to the brighter component, mag. +2.7 Alpha2. Alpha1 is an F3type…

The planetary defence method that we choose against asteroids depends on the size and composition of the asteroid and how much warning we have. A kinetic impactor, such as DART, has proved it can alter an asteroid’s trajectory by slamming into it. This method has been tested and would be quick to deploy and easy to control, making it the preferred choice. Interestingly, the debris observed streaming from Dimorphos after DART’s impact had a stronger push on the asteroid than the impact itself. Other methods of deflection are more indirect and include a gravity tractor – a spacecraft that would fly alongside an asteroid using the ship’s gravity to change the asteroid’s orbit – or a spacecraft powered by an ion engine that could aim the ion beam at an…

Astronomers have discovered that about 85 per cent of matter in the Universe is invisible. This mysterious stuff doesn’t interact with ordinary matter or radiation, but does exert a gravitational force. ‘Dark matter’ is the concept needed to explain many things, such as how galaxies hold themselves together and the temperature distribution of hot gas in galaxy clusters. Yet despite its ubiquity, we have no idea what dark matter is. It may be subatomic particles like heavy neutrinos or other hypothetical particles called axions. Some of it may be undiscovered elementary particles called WIMPs (weakly interacting massive particles). But currently scientists are at a loss. Dark matter has often been portrayed as a sinister, destructive force, as if ‘dark’ refers to its inherent evil. But by its very nature, this…

Albert Einstein’s theory of relativity started with a simple fact: light always travels at the same speed, no matter how fast the light source is moving. This might not seem very odd, but it leads to a startling conclusion: the passage of time differs depending on your motion relative to others. Let’s try one of Einstein’s thought experiments. You’re in a moving train carriage and have placed torches at each end facing towards the centre. If you turned the torches on simultaneously, you would not be surprised to see the two light beams arrive at the centre at the same time. If you had a friend who was watching from the station as the train passes by, they would see the two light beams travel at the same speed relative…

In early April, NASA’s James Webb Space Telescope completed its third observing programme, a nine-month-long roster of research proposed by astronomers around the world. Among the many groundbreaking projects in the infrared telescope’s packed schedule was the most ambitious attempt so far to track down an entirely new class of alien world. Exomoons, as the name suggests, are satellites of exoplanets. These worlds are tantalising for several reasons. Their discovery could tell us more about how planetary systems form and they could open up new ways to study the properties of their parent planets. Most intriguingly, they could vastly increase the number of potentially habitable worlds suitable for life to evolve. Tracking down exomoons, however, is a challenge that pushes current technology to its limits. In 2018, astronomers found the…

When the full Moon occurs near the horizon, it looks artificially massive. Even if you’ve been into astronomy for a long time, this can still catch you out, convincing you that that low-down full Moon, or near-to-full Moon, is indeed larger than it should be. But this is false, an illusion conjured up by our brains. This month’s Capture shows you how to debunk the illusion. While our brains have trouble not seeing the Moon as huge when it’s near the horizon, a camera isn’t fooled at all. This is especially true when you see a low full or gibbous Moon near the horizon and try to capture its apparently massive appearance with a smartphone. The resulting image shows nothing particularly impressive. The camera can’t see the illusion, so it…

What did your team discover? We discovered around 2,600 low-mass, very low-surfacebrightness, faint galaxies from data released by the Euclid space mission. These are historically very hard to find because they’re so small and faint, but they’re the most numerous galaxies in the Universe. Our dataset was from only 0.4 per cent of the total survey we will eventually get from Euclid, so this was an initial survey of a much larger dataset. What is Euclid? Euclid is a space mission that ESA launched in 2023. Its goal is to take images and spectral data in the optical and infrared of around one third of the sky. It does that with fantastic sharpness, because the telescope is in space and responsive to very low brightnesses. One of Euclid’s goals is…

JAMES WEBB SPACE TELESCOPE, 24 MARCH 2025 Scientists working with the James Webb Space Telescope have likened this object to an ice cream sundae. Others examining it with the nowdefunct Spitzer Space Telescope dubbed it the cosmic tornado. To us, it looks like a fir cone or a giant tardigrade. What we’re actually looking at is a chance alignment of Herbig–Haro 49/50, which lies 625 lightyears from Earth in the constellation Chamaeleon, and a distant spiral galaxy. Herbig–Haro objects form when material from newborn stars ploughs into denser regions nearby, gets heated by the resulting shockwave and emits light. The fact that this Herbig–Haro appears to have a spiral galaxy perched on top of it is a sheer fluke, a cosmic configuration only made from our perspective in space –…

NASA’s Curiosity rover has unearthed the largest carbon chains yet found on Mars. Containing up to 12 carbon atoms, these chains could exhibit similar features to fatty acids, considered some of the building blocks for life on Earth. The molecules were found using SAM (Sample Analysis at Mars), an instrument on the Curiosity rover, in a rock sample collected years ago from a dried-up lakebed named Yellowknife Bay. A thorough re-examination of the sample resulted in the discovery of chains of between 10 and 12 carbon atoms long. Astronomers believe these long carbon molecules, or alkanes, were preserved in clay-rich deposits on Mars, aided by the planet’s cold temperatures. They are thought to be around 3.7 billion years old, aligning roughly with when life first emerged on Earth. We don’t…

The Trump administration has proposed a series of severe cuts to NASA’s funding in a draft version of its budget. The initial budget request calls for an average 20 per cent cut, with severe cuts to heliophysics, Earth science and planetary science budgets. The harshest reduction comes to astrophysics, which has its budget slashed by two thirds, down to around $487 million. “This is an extinction-level event for NASA science,” says Casey Dreier, chief of space policy for the Planetary Society, in a statement to the Washington Post. The proposal has been met with opposition across the political spectrum, but experts are concerned NASA will be forced to make operational plans based on the draft budget as soon as October. “This is a wholly unserious budget proposal,” says Senator Chris…

The origin of Mars’s two moons, Phobos and Deimos, has long been a matter of debate. The idea that they are captured asteroids has been popular in the past, but the fact that they both orbit close to Mars’s equatorial plane means that most planetary scientists today accept it is much more likely they formed from a disc of rock and dust circling the planet. Such a circum-Martian disc was probably formed of ejecta from a giant impact into the Red Planet. Phobos, the larger and inner of the two moons, is spiralling ever closer to Mars due to tidal effects and will probably be broken apart by these forces within a few tens of millions of years. But Phobos’s past could have been even more dramatic. The traditional hypothesis…

It was 15 years ago this month, on 13 June 2010, that the world watched as a beleaguered traveller finally arrived home, after a long and perilous journey back to land. The trouble began in 2003, as All Hallows’ Eve approached. All seemed calm as the vessel Hayabusa (Japanese for mighty falcon) sailed through the darkness towards uncharted shores. Unbeknown to the crew, though, the ship was about to be hit by one of the fiercest storms in recorded history. This could be an account from a 15th-century ship’s log, but it is in fact a tale of the Space Age. Hayabusa was a robotic spacecraft sailing through interplanetary space on a two-year journey to rendezvous with asteroid 25143 Itokawa when it was battered by a series of massive eruptions…

PICK OF THE MONTH Mercury Best time to see: 15 June, from 40 minutes after sunset Altitude: 5° (low) Location: Gemini Direction: Northwest Features: Phase, surface features Recommended equipment: 100mm or larger Remember the glory days at the end of 2024 and beginning of 2025 when there were planets everywhere? Well, that’s not the case currently, with some very close to the Sun and others compromised by the bright skies of June. Little Mercury meanwhile continues to do what it does best, flitting back and forth on either side of the Sun. This month finds it on the eastern or evening side of the Sun, a potential target if you have a good flat northwestern horizon. At the start of June, Mercury isn’t that well placed, located just 3.5° from the Sun and setting shortly…

1. The Horn of Plenty Look 2° northwest of mag. +4.2 Kang (Kappa (κ) Virginis) to see a little trio of stars, the brightest of which is mag. +5.5 95 Virginis. This marks the convergence of two irregular long arcs of stars that create a horn-shaped asterism extending about 12° to the northwest. In mythology, Virgo is often depicted as carrying an ear of wheat, marked by mag. +1.1 Spica (Alpha (α) Virginis), and a cornucopia. Is this the latter? □ SEEN IT 2. Vesta Vesta, the fourth asteroid to be discovered (in 1807 by Heinrich Olbers), was named after the Roman goddess of the hearth by mathematician Carl Friedrich Gauss, whose calculations confirmed the orbits of early asteroid discoveries. In June, watch it travel a tight arc from mid-way…

On 27 December 2024, the Asteroid Terrestrial-impact Last Alert System (ATLAS) telescope in Rio Hurtado in Chile discovered asteroid 2024 YR4 speeding past Earth. The detection could have been too late; only two days before, on Christmas Day, the asteroid had been just 828,800km (515,000 miles) from Earth. As astronomers plotted out the path of the asteroid, they realised Earth might not always be so lucky – there was a chance the asteroid could impact our planet in December 2032. Telescopes across the globe have been gathering data on YR4 ever since. Chief among these was the Nordic Optical Telescope in La Palma which analysed the asteroid’s size, shape and rotation, as well as its motion and exact position. This helped to refine its current orbit and predict its future…

If you place an object in space, the temperature it attains depends on how much radiation it receives and how good it is at absorbing or emitting that radiation. Put it near a star and it will generally heat up, for example. Spacewalking astronauts in Earth orbit in direct sunlight can experience temperatures up to 120°C (248°F), which is far from cold. However, the object’s (or astronaut’s) temperature is not the temperature of ‘space’. Space itself, being ‘nothing’, doesn’t have a temperature. Astronomers do refer to the temperature of a region of space to indicate the kinetic energy of matter in that region. Clouds of molecular hydrogen gas are generally cold at around 10K (–263°C or –441°F), while regions between galaxy clusters can reach temperatures of 10,000,000°C (18,000,000°F). Again, by…

It’s common to say astronauts on the International Space Station are ‘weightless’ or in ‘zero gravity’. But being weightless doesn’t mean there’s no gravity. In fact, these astronauts experience about 89 per cent of the gravitational field they’d feel here on Earth if they were about 400km (250 miles) up. The difference is that the astronauts are in Earth orbit. They’re in a continuous state of gravitational freefall, but their large orbital speed means their trajectory matches the curvature of Earth. In short, they’re falling towards, but constantly missing, Earth. If they were instead standing on top of a 400km-high building, they’d feel 89 per cent as heavy as they do on the ground. What about deep space? Space is full of gravity because the Universe is full of matter.…

Black holes are commonly depicted careering through space devouring everything in their path. However, their gravitational pull is no stronger than any other kind of object of the same mass. If the Sun suddenly turned into a black hole of the same mass, for example, it would have no effect at all on the orbits of the planets. Except, of course, we would all die due to the lack of sunlight. So are black holes dangerous or not? They can be, if you get too close. With a regular star (or planet), the maximum gravitational force is at the surface, because inside the star the gravity of the material above counteracts that lying below. But black holes have a lot of mass compressed into a small volume. As we approach…

For astrophotographers, gradients are a common problem, even if photographing from a dark site. Caused by light pollution, either from artificial lighting or Moon glow, they make backgrounds look uneven and can particularly affect faint targets like nebulae. They can become more obvious when you stack your frames, detracting from fainter details. Thankfully, there are options to help. Siril is a powerful, free processing program with a built-in gradient-removal tool called Background Extraction. It’s best to remove gradients after stacking your image, before any stretching or processing. We’ll therefore start with a freshly stacked image of the Rosette Nebula made from 105 sub-frames. If your stacked result shows artefacts on the edges, it’s best to crop the image before using Background Extraction. To see the level of gradient you’re working…

Dark energy’s pull could be weakening over time, according to new results from the Dark Energy Spectroscopic Instrument (DESI) collaboration. The Universe has been expanding at an accelerating pace since the Big Bang over 13.8 billion years ago, and cosmologists have long believed this expansion was enabled by the Universe’s most mysterious quantity – dark energy. Most think dark energy’s pulling power is the same now as it was at the dawn of the Universe, an idea that arises from a widely accepted model of the Universe, known as Lambda cold dark matter or Lambda-CDM. The DESI collaboration put this model to the test by creating the largest 3D map of the Universe ever made and tracking the influence of dark energy over 11 billion years. By overlaying the DESI…

Whether life exists beyond Earth remains one of the great unresolved paradoxes of our age. Now a team of scientists from Cambridge University claim to have found the strongest evidence yet for potential biological activity on another world. By pointing JWST at exoplanet K2-18b, 124 lightyears from Earth, they found the molecular fingerprints of dimethyl sulphide (DMS) and dimethyl disulphide (DMDS). On Earth, these compounds can only be formed by life. While the discovery sounds like a watershed moment for humanity, the study’s lead scientist Professor Nikku Madhusudhan tempers his optimism: “We are very cautious. We have to question ourselves both on whether the signal is real and what it means.” There are still several leaps required before the team can say for sure that the signal points to life.…

Email us at inbox@skyatnightmagazine.com MESSAGE OF THE MONTH On 1 April, my wife Myra and I with our Celestron Inspire 100AZ refractor took off to a less light-polluted site, resulting in a very enjoyable night’s viewing. We arrived just before twilight, which gave us plenty of time to set things up, allowing us to experiment with lenses and telescope positions. With the sounds of geese in the background, we started to observe the Moon, Jupiter and various other bodies in the night sky, which we never get tired of doing. Then our focus turned to the Pleiades with the occultation with the Moon, so we thought we would have a go at photographing the event, something we are totally inexperienced in doing. Myra took a number of images using her…

On 15 October 2024, solar scientists announced that we had entered solar maximum, the peak of the Sun’s approximate 11-year cycle of activity, which is expected to last for around a year. In May 2024, a CME sparked the strongest geomagnetic storm since Halloween 2003 and we were treated to beautiful displays of the aurora here in the UK. Fortunately, we’ve learned a lot since the 2003 event. Better space weather forecasting and improved radiation hardening of electronic components meant most spacecraft were undamaged. Solar maximum occurs because the Sun is made of plasma, an intensely hot soup of charged particles that, when in motion, generate magnetic fields. At solar minimum, the magnetic field of the Sun has a relatively simple shape that is concentrated at the poles. However, the…

We leave La Serena at dusk, heading east towards the stars. The 90-minute drive winds through the Elqui Valley, lush green with vineyards and home to skies so dark that international observatories on Cerro Tololo and Cerro Pachon are sited here, shining on distant mountaintops silver and rose-gold in the setting sun. Our destination is a small private observatory and our goal is to stare into the Universe. The chance to do so is the reason I’ve travelled to northern Chile, where clear dry air and pristine skies have made it the world’s most important area for astronomy. That I would want to travel 5,000 miles just to see what every human for most of history could see by stepping away from the campfire, or by leaning out of the…

Venus Best time to see: 30 June, 50 minutes before sunrise Altitude: 11° Location: Taurus Direction: East Morning planet Venus rises just before 03:30 BST (02:30 UT) on 1 June. Sunrise is just before 05:00 BST (04:00 UT), providing a 40-minute or so window to try to catch the mag. –4.2 planet. On 1 June, Venus reaches greatest western elongation, separated from the Sun by 45.9°. Through a telescope on this date, Venus appears 23 arcseconds across and 50% lit. However, according to the phase anomaly, the observed 50% phase is supposed to be late by a few days for morning appearances. On 22 June, a 15%-lit waning crescent Moon lies 5.9° north of Venus, a lovely sight given clear skies. By the end of the month, Venus rises nearly 2.5 hours before…

Minor planet 89 Julia next reaches opposition on 10 August 2025, when it can be found among the stars of southwest Aquarius, north of the triangularshaped pattern of Capricornus. On 1 June at 01:00 BST (00:00 UT), 89 Julia shines at mag. +10.7, 49 arcminutes southeast of mag. +4.7 Kappa (κ) Capricorni. It then traces an arc around the eastern tip of Capricornus’s main triangle, lying 1.6° east of mag. +2.9 Deneb Algedi (Delta (δ) Capricorni) at 01:00 BST (00:00 UT) on 1 July. The arc then continues northwest throughout the rest of July, the minor planet increasing in brightness from mag. +10.2 on 1 July to +8.7 on 10 August when at opposition. The bright, nondark June sky will present issues with keeping track of Julia, but you’ll have…

During June evenings, the beautiful red supergiant Antares (Alpha (α) Scorpii) can be seen passing above the southern horizon. This ‘rival of Mars’ represents the heart of Scorpius, the scorpion, a constellation that’s reduced in intensity for UK observers because it doesn’t rise high enough above the southern horizon. Fortunately, this is not the case for Antares, which can reach the giddying heights of 10° altitude when due south. Okay, that’s not great, but Antares is bright enough to punch through any gentle summer haze and stands out really well. This month’s challenge lurks within the glare of Antares. Antares shines at mag. +1.0 and has a beautiful orange hue – hence the comparison to Mars, the two objects not appearing totally dissimilar. Like many stars, Antares is not alone…

Asteroids can have a wide variety of compositions. They can be made of rock, metals and even water. There are very dark chondrite or C-type asteroids which are the primitive leftovers from planet formation that have remained largely unchanged for billions of years. There are also metallic M-type asteroids and grey stony S-type asteroids, which is what YR4 is thought to be. Though there have been missions to analyse asteroids close up, their composition is usually estimated remotely by measuring their albedo (how much light is reflected from the surface) and spectra, and by calculating their density. Most stony asteroids are made of loose rubble formed by collisions and bound by gravity, though only the largest have enough mass to pull them into a spherical shape. Metallic asteroids are more…

The idea that the Sun is somehow burning has been around since ancient times. The Sun’s heat and light were often attributed to molten metal or burning coal. But, armed with new knowledge of chemistry and thermodynamics, 19th-century scientists realised that no form of chemical energy was sufficient to fuel the Sun for more than a few thousand years. Instead of chemically combining with oxygen, like carbon does when coal is burnt, the Sun’s fuel is undergoing thermonuclear reactions. Most of its energy is produced by the fusion of hydrogen into helium deep in the Sun’s core, where temperature and pressure are huge. Astronomers calculate the Sun is losing about 4.26 million tonnes of mass every second due to fusion (140 quadrillion tonnes per year). Since the Sun’s mass is…

Since Earth’s orbit around the Sun is slightly elliptical, its closest approach to the Sun (perihelion) is about 147 million km (91 million miles) and its furthest (aphelion) is about 152 million km (94 million miles). This 3 per cent or so difference means the Sun’s light is on average 7 per cent stronger at perihelion than at aphelion. So, you might think that this creates a seasonal difference in the Sun’s warmth. But perihelion occurs in January, the dead of winter for the Northern Hemisphere; yet at the same time, the Southern Hemisphere experiences its summer. The seasons are caused by the 23.4° tilt of the Earth’s spin axis from its orbital plane. As Earth moves through its orbit, first one and then the other hemisphere tilts towards the…

As of now, astronomers have discovered over 5,800 exoplanets. The two main methods used to find these elusive distant worlds (the transit method and the radial velocity method) are more suited to discovering large exoplanets or those close to their host star. This means Earth-like exoplanets are hard to find. Even so, one study concluded that 22 per cent of Sun-like stars have Earthsized planets in their habitable zones. Even if this estimate is too high, there are so many stars in the Universe that the number of Earth-like exoplanets remains huge. One estimate suggests there may be 2.6 billion Earth-like exoplanets in our Milky Way Galaxy alone. And there are probably upward of 10 trillion galaxies in the Universe. Our closest Earth-like exoplanet is Proxima Centauri b, orbiting the…

CCD and CMOS astrophotography cameras have been on the market for many years and allow amateur astrophotographers to produce stunning image results. But to get the best from your astro camera, you need to really understand and master its settings. If you’ve just bought one or you’ve had one for a while but you’re not getting the results you hoped for, it’s time to learn all about it – and learn from examples of good (and bad!) imaging results. We’ll run through how to judge your settings both during and after a ‘first light’ session. Much can also be learned in post-processing, meaning you can tweak settings on the next clear night. There are four main settings to focus on: exposure, binning, gain and offset. Exposure is how long (in…

PHOTO OF THE MONTH Aurora borealis Alessandro Scalas, Lofoten Islands, Norway, 12 February 2025 Alessandro says: “The sky was cloudy, but then it opened up and started to turn green, and I was amazed to see a moonbow reflecting the light of the full Moon behind me. It was a fantastic experience, despite the extreme cold!” Equipment: Nikon Z7 II camera, Nikkor Z 14–30mm lens, Leofoto Ranger LS-254C tripod Exposure: ISO 3200 f/4.0, 6” Software: Camera Raw Alessandro’s top tips: “Travel, have fun and take pictures! Plan your adventures, choose the spot to photograph and check the weather carefully. And if sometimes the sky offers only bad jokes, don’t despair -there is often a surprise in store, as happened to me when the cloudy skies opened and gave us this…