Innholdsfortegnelse for April 2025 i BBC Sky at Night

Find it at www.skyatnightmagazine.com/bonus-content APRIL HIGHLIGHTS Will we find life beyond Earth? Astrobiologist Lisa Kaltenegger gives her thoughts on one of the biggest unanswered questions of our time. Binocular and deep-sky tours Download and print off charts to help you find some of the best deep-sky targets listed in this month’s Sky Guide. Extended astro image galleries Amazing images of the cosmos by professional telescopes, spacecraft and 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.…

A giant planet just 244 lightyears from Earth has been uncovered within data gathered by the Gaia satellite. The discovery of Gaia-4b marks the first time the spacecraft’s data has been solely responsible for an exoplanet discovery. Gaia ended its scientific operations in January 2025, but its data will still be analysed for years to come. For a decade, the craft has monitored the positions of billions of bright stars, a technique called astrometry. For stars in our local cosmic neighbourhood, the measurements were accurate enough to detect the stellar ‘wobble’ created by the gravitational pull of an orbiting planet, which makes the star appear to move across the sky with a corkscrew motion. There are many stars that show such motion, but Gaia-4b is the first to be confirmed…

Back in 2022, I spoke to the Sky at Night TV show and this magazine about the impending launch of a mission I’d spent the last seven years working on. At the time, we were on the cusp of sending a small but ambitious spacecraft to the Moon – one that aimed to push the boundaries of what CubeSats could achieve in deep space. The Lunar Polar Hydrogen Mapper, or LunaH-Map, was designed to map water and ice hidden within permanently shadowed regions near the lunar poles. Launched on 16 November 2022 as a secondary payload aboard Artemis I, it aimed to demonstrate how small spacecraft could conduct high-value planetary science. A CubeSat about the size of a shoebox, LunaH-Map carried a miniature neutron spectrometer and an iodine-based electric propulsion…

Email us at inbox@skyatnightmagazine.com MESSAGE OF THE MONTH During January and February, the Gaia spacecraft went through a series of end-of-mission engineering tests that put it into an orientation that reflected more sunlight towards Earth and made it a better imaging target. Here’s the image of it I managed to take from my garden in suburban Surrey. It shows the track of the spacecraft relative to the stars during almost a complete passage across the sky, from 8:30pm on 4 February to 5:30am the next day. During the run, a total of 250 frames were shot at around two-minute intervals and I used 84 of these for the Gaia track. Gaia is at the L2 Lagrange Point, about 1.5 million kilometres away from Earth in the direction opposite to the…

Today, many amateur astronomers use computerised Go-To telescopes that find objects automatically. That’s good for suburban observers when it comes to the Realm of the Galaxies, where few stars will guide you to targets the old-fashioned way with a finderscope, especially in the galaxy-rich area encompassed by the stars Epsilon and Nu Virginis. Go-To may make finding galaxies easy, but it doesn’t make identifying them simple. Even accurate Go-To telescopes don’t always place target objects dead centre. In the heart of the Virgo Cluster, there are often multiple fuzzballs in the eyepiece. Which is the target? One helpful tip is something I used to call ‘eyepiece hopping’. An eyepiece-field-sized chart, with each galaxy labelled, makes it easy to identify the quarry; you hop from galaxy to galaxy in the eyepiece…

1 Tuesday This evening, the 16%-lit waxing Moon passes in front of the Pleiades open cluster, offering numerous opportunities to see lunar occultations of its member stars. See page 46 for further details. 2 Wednesday Around midnight, the 26%-lit waxing crescent Moon sits slightly under 5° north of mag. –2.0 Jupiter. Closest approach is around 00:30 BST on 3 April (23:30 UT on 2 April). 5 Saturday Mag. +0.5 Mars lies 1.6° south of 58%-lit waxing Moon this evening. Clair-obscur events visible: Lunar X and V 13:00 BST (12:00 UT), Nessie (Ptolemaeus crater) 22:40 BST (21:40 UT), Face in Albategnius 20:55 BST (19:55 UT). 8 Tuesday The superb Jewelled Handle clair-obscur effect is visible on this morning’s 79%-lit waxing gibbous Moon. View around 04:00 BST (03:00 UT), when the Moon can be seen low…

PICK OF THE MONTH Jupiter Best time to see: 1 April, 21:00 BST (20:00 UT) Altitude: 40° Location: Taurus Direction: West-southwest Features: Complex atmosphere, satellites Recommended equipment: 75mm or larger Jupiter’s observing window slowly closes this month, thanks to the planet’s move closer to the Sun combined with the expanding evening twilight. On 1 April, Jupiter shines at mag. –2.0 and is positioned 40° above the westsouthwest horizon as evening twilight darkens. A 16%-lit waxing crescent Moon can be seen further to the west of Jupiter (down and right as seen from the UK) that evening. On the evening of 2 April, a 25%lit lunar crescent will now be quite close to brilliant Jupiter. As the pair approach setting at around 01:30 BST (00:30 UT) on 3 April, the Moon will be located 4.7° north…

1. M3 We’ll start the tour with one of the best globular clusters in the northern sky. There are no nearby bright stars to help you find it. However, if you look mid-way between Arcturus (Alpha (α) Boötis) and mag. + 2.9 Cor Caroli (Alpha (α) Canem Venaticorum), you should find what looks like a badly focused star. This is the glow of the nearly half-million stars of globular cluster M3. □ SEEN IT 2. M53 Our next globular cluster lies 1° north-east of mag. +4.4 Diadem (Alpha (α) Comae Berenices). This tiny misty patch will appear to grow in size, fuzziness and brightness if you centre it in the field of view and then avert your gaze back to Diadem. This is M53, and the apparent changes you just…

When Shakespeare came to contemplate the time and tides of human existence, he had Jaques in As You Like It speak of a man’s life split into seven distinct ages: infant, schoolboy, lover, soldier, justice, pantaloon and old age. The Universe itself is no different. Its tumultuous history can be also be broken down into eras. It is a story that starts with a fiery childhood, followed by the growing pains of adolescence and the wild abandon of a mid-life crisis. Let’s explore these chapters in its life as we take a trip through the history of the Universe. The first fraction of a second It’s often said that our earliest experiences shape the people we become. This is definitely true of the cosmos. According to the latest theories, our…

Although they could be considered the stuff of terrifying science fiction, in reality black holes are common throughout the Universe. They aren’t really holes, portals or cosmic vacuums either: instead, they’re the result of infinitely dense points, which cause spacetime to warp around them so that not even light can escape. Black holes range in size from those with masses a few times that of our Sun to giants with billions of times that mass. At the lighter end are stellar-mass black holes, the last stage of stellar evolution for massive stars. When these massive balls of gas run out of fuel, they no longer experience an outwards pressure resisting the pull of their own gravity. They collapse, creating a singularity – a point of infinite density – while their…

VITAL STATS • Price £519 (£492 via DwarfLab) • Optics Wide-angle and telephoto lenses • Aperture 35mm • Focal length 150mm • Equivalent focal length 737mm (tele), 45mm (wide) • Sensor Sony IMX678 Starvis 2 • Power: Built-in 10,000mAH battery • Storage 128GB eMMC • Ports USB-C • App control DwarfLab app • Connectivity Wi-Fi, near field (NFC) one-touch • Weight 1.3kg • Extras 2x magnetic solar filters, USB-C cable, wipe cloth, carry bag • Supplier DwarfLab • Email support@dwarflab.com • www.dwarflab.com Smart telescopes have been taking the market by storm, with DwarfLab’s Dwarf II originally standing out due to its portability. Now DwarfLab is back with the Dwarf 3, which features a larger aperture, longer focal length and greater storage capabilities, in addition to new shooting modes, internal…

HUBBLE SPACE TELESCOPE, 4 FEBRUARY 2025 This is LEDA 1313424, a spiral galaxy that’s around 2.5 times larger than our own Milky Way. Uniquely, LEDA 1313424 has nine rings, where other spiral galaxies have a maximum of three – giving the object its nickname, the Bullseye Galaxy. That’s because, around 50 million years ago, the blue dwarf galaxy seen to LEDA 1313424’s immediate left passed right through its larger neighbour. This extremely rare event sent waves of material flying both inwards and outwards, which then coalesced into the series of concentric rings seen today. FREE BONUS CONTENT Explore a gallery of these and more stunning space images www.skyatnightmagazine.com/bonus-content Coming up roses GEMINI SOUTH, 14 FEBRUARY 2025 Open cluster NGC 2040 here reveals its surrounding nebulosity as never before. Reds and…

President Donald Trump looks set to make sweeping changes at NASA, potentially changing track from landing on the Moon to Mars. In his inaugural address, Trump stated: “We will pursue our Manifest Destiny to the stars, launching American astronauts to plant the Stars and Stripes on the planet Mars.” The announcement left many wondering if the Artemis programme, which aims to put the first woman on the Moon, but has been plagued by cost overruns and delays, could soon be on the chopping block. As of the time of writing, no official statement had been given about the future of the Artemis programme. In early February, NASA’s acting administrator Janet Petro confirmed that members of the Department of Government Efficiency had arrived at NASA and were in the process of…

Meteor strikes impacting the surface of Mars could shake the Red Planet far more deeply than previously thought. The revelation came after planetary geologists used a new AI algorithm to link the appearance of new impact craters in images from the Mars Reconnaissance Orbiter (MRO) with seismic information from the InSight lander. NASA’s InSight lander spent four years on Mars listening out for ‘marsquakes’. By the time it retired in 2022, it had discovered 1,300 such seismic events, many from meteor impacts. In some cases, astronomers were able to match these with recent impacts detected by the MRO. As MRO photographs the same areas over and over again, it’s possible to find new craters by comparing old images with new ones. However, it would take a human many years to…

As of this month, over 5,500 exoplanets have been discovered orbiting other stars in the Galaxy. This tells us that planet formation is a universal process across the Milky Way and the majority of stars probably have at least one planet. But before you plan an extraterrestrial trip, you’ll want to pin down the best Galactic neighbourhood to visit. Not every planetary system looks the same: there are differences between the number of gas giant planets and lower-mass, mostly rocky worlds. So, where will you most likely find the kind of planet you’re after? The difference stems from how gas giants form through core accretion. First, a mass of rocky material and ice around 10 Earth masses in size clumps together. Then, the powerful gravity of this core pulls in…

Most scientists agree that nothing and no one can travel faster than the speed of light – with the possible exception (at least according to the late Douglas Adams) of bad news. However, the good news is that there’s one way in which we can all break the light barrier, metaphorically – and you don’t even need a spaceship. Last October, the Dirleton Solar Walk officially opened in East Lothian, near Edinburgh, Scotland. This 1:3.6 billion scale model of the Solar System, which stretches just over 1.2km (0.7 miles), means that every step you take represents millions of kilometres in space. To complete the route in either direction, even at a slow pace, means that – symbolically, at least – you’re necessarily breaking the laws of physics. Currently there are…

Earth is often considered to be a water world: over 70 per cent of our planet’s surface is covered in oceans. Since our planet orbits within what’s known as the ‘Goldilocks zone’ around the Sun, the warmth it receives is just right for keeping water in its liquid state. But there are several moons in the outer Solar System that are also known to hold significant bodies of liquid water. Subsurface oceans Beyond Earth’s orbit, the Sun doesn’t deliver enough warmth to keep water liquid and so these extraterrestrial oceans, or exo-oceans, are kept liquid by a different source of energy. Many of the moons orbiting the gas giant planets Jupiter and Saturn experience significant amounts of tidal heating. The gravitational pull of the parent planet causes two symmetrical bulges…

Mercury Mercury is a morning planet this month, reaching an impressive greatest western elongation, separated from the Sun by 27.4° on 21 April. Despite this, the planet’s position is not good from the UK and consequently it’s unlikely to be visible this month. Venus Best time to see: 1 April, 21:10 BST (20:10 UT) Altitude: 59° Location: Gemini Direction: South Along with several other planets, Venus can be found in the morning sky this month. On 1 April, Venus rises at 05:40 BST (04:40 UT), some 70 minutes before the Sun. It’s a bright object shining at mag. –4.1 and, having passed inferior conjunction last month, remains large with a small phase. On 1 April, through the eyepiece of a telescope Venus appears 56 arcseconds across and 3% lit, a beautifully slender crescent.…

Asteroid 4 Vesta reaches opposition on 2 May, when it can be found shining among the stars of northern Libra, close to the constellation’s boundary with Virgo. At opposition, it’s predicted to reach mag. +5.7, which places it within naked-eye territory from a dark-sky site, although binoculars are a better way to catch it. On 1 April, mag. +6.6 Vesta sits 3° north of mag. +2.6 Zubeneschamali (Beta (β) Librae), thereafter proceeding to the westnorthwest towards the mag. +4.5 star 16 Librae at the start of May. Its path arcs slightly north as it goes, taking it through a fairly barren part of the spring sky. Discovered on 29 March 1807, Vesta was the fourth asteroid identified – hence its prefix ‘4’. It’s the second most massive and second-largest body…

Amateur astronomers can make a valuable contribution to solar science through their observations and images of the Sun. You may be a seasoned expert in solar photography or a complete beginner, but why not use your skills for citizen science? Keep a logbook of your observations and any images or sketches you make. Make sure each record contains your name, the date, the location and the time in UT. In the UK, the British Astronomical Association’s Solar section welcomes amateur data, as does the American Association of Variable Star Observers (AAVSO). And data on sunspots specifically can be submitted to the Sunspot Index hosted by the Royal Observatory of Belgium.…

One of the big differences between the early and modern Universe is how galaxies look. The first galaxies tended to be smaller and long and thin. Today’s galaxies are usually either flat, spiral galaxies like our own Milky Way or rugby-ball-shaped elliptical galaxies. Early galaxies also had a much higher rate of star formation. Today, only 4–8 Suns’ worth of material is turned into stars within the Milky Way every year. In the earliest galaxies, it’s more like hundreds of Suns’ worth. Over time, the structure of the Universe has also become more intricate. Today, the cosmos resembles a giant web, with vast filaments and superclusters of galaxies strung out like fairy lights on invisible cord of dark matter. Yet this took time to construct. Astronomers have spotted the first…

As bodies move through the Universe, they emit gravitational waves that stretch and squeeze anything they pass through by a tiny amount. When two black holes merge, they create immense gravitational radiation, which can be picked up by gravitational-wave detectors on Earth. These detectors have two 4km-long (2.5-mile) arms. Light travels down each arm and is reflected back at the end, before both beams are picked up by the detector. By comparing the two light beams using a technique called interferometry, the detector can see if they’ve been stretched or squeezed by passing gravitational waves. This allows astronomers to reveal the properties of the black holes that created the waves. In 2019, the first direct images of a black hole were taken by the Event Horizon Telescope (EHT). This is…

Astronomy Photographer of the Year Advice from a highly commended entrant in 2024’s awards Capturing the Universe in motion is one of the most exciting aspects of astrophotography. It pushes the limits of both your equipment and imagination. With the help of digital planetarium software, it’s possible to prepare for special alignments between celestial objects. This is exactly how I was inspired to capture my image of the dwarf planet Ceres transiting the Mirror Galaxy, M100, that was highly commended in the Planets, Comets and Asteroids category of 2024’s APY competition. Preparation for this sort of image is arguably as important as the processing steps themselves. I used Stellarium to research multiple small celestial objects. Ceres was the most exciting of the bunch, so I changed the date and time…

VITAL STATS • Price £199 • Design Maksutov– Cassegrain • Optics 80mm primary mirror • Focal length 850mm, f/10.6 • Focuser Friction-drive • Mount 45mm Vixen/ Sky-Watcher dovetail bar, ¼-inch tripod thread • Extras Diagonal, 12.5mm and 20mm eyepieces, 6x21mm finderscope, smartphone adaptor, carry case • Weight 1.5kg (OTA) • Supplier Optical Vision Ltd • Email info@opticalvision. co.uk • www.opticalvision.co.uk Maksutov–Cassegrain telescopes are ‘catadioptric’ instruments that are particularly compact because the light path from the primary mirror is ‘folded’ by the secondary mirror, meaning they pack a long focal length into a short tube. Their corrector plates, placed at the front, correct coma and chromatic aberrations. We tested Acuter’s latest lightweight model, the Voyager MAK80-Fast, which boasts a respectable 850mm focal length. It takes over from its predecessor, the MAK80,…

The sighting of a dangerous asteroid on a potential collision course with Earth has triggered planetary defence response procedures for the first time ever. Fortunately, the process successfully tracked the asteroid to reveal it will almost certainly miss Earth. Asteroid 2024 YR4, discovered in December 2024, is estimated to be 40–90 metres in diameter. When astronomers realised the danger, they mounted an observing campaign to measure its orbit and more accurately gauge whether it would impact Earth. The probability of impact with Earth fluctuated as more measurements came in, reaching as high as 3.1 per cent. That put the space rock at a three out of 10 on the Torino scale, which measures the danger of potential impacts – only asteroid Apophis has been rated more highly. The scale combines…

Movement is often one of the clearest signs of whether something is alive or not. Taking advantage of this, a new test which prompts microbes to move could be adapted into a novel way to hunt for life on other planets. The test uses a chemical called L-serine, which is one of the amino acids on which all Earth life is based. Scientists placed this chemical next to three different organisms and found that they all moved towards the L-serine. “This movement, known as chemotaxis, could be a strong indicator of life and could guide space missions looking for living organisms on Mars or other planets,” says Max Riekeles of the Technical University of Berlin, who led the study. L-serine is known to inspire movement in a wide variety of…

One spring afternoon, many years ago, I was idly thumbing through an astronomy book from the library when I came upon a spring star chart with a portion of the sky labelled ‘The Realm of the Galaxies’. That sounded so intriguing, I began reading in earnest. I learned this ‘realm’ is a great cluster of galaxies called the Virgo–Coma Cluster, island universes just like our Milky Way. It stretches across the spring sky from northernmost Coma Berenices to southernmost Virgo and is home to some 2,000 galaxies. While the Milky Way is a member of this Virgo–Coma Cluster, the heart of this great agglomeration of galaxies is a mind-bending 54 million lightyears distant. By the time I finished reading, I wanted to see the Realm for myself. My journey through…

One October day in 1969, Soviet cosmonauts Georgi Shonin and Valeri Kubasov attempted in-space manufacturing for the first time. They closed the hatch to the orbital module of their Soyuz 6 spacecraft, retreated to the descent module and activated a vacuum-welding furnace for a series of autonomous tests. What happened next could have killed them both. Three months after Neil Armstrong and Buzz Aldrin walked on the Moon, a dispirited yet resurgent Soviet Union realigned its efforts to building Earthcircling space stations. Cosmonauts would no longer simply visit space, but live there. And that meant assembling huge off-world structures, fixing or strengthening components weakened by long-term exposure to the low-gravity, high-vacuum and highradiation environment in Earth orbit. Aboard Soyuz 6 was a squat green cylinder the size of a small…

DON’T MISS Lunar occultation of the Pleiades BEST TIME TO SEE: 1 April from 21:15 BST (20:15 UT) The Moon has been skirting close to the Pleiades open cluster for several months, sometimes passing across some of its outer members. However, on 1 April, starting under conditions of deep twilight, from the vantage location of the UK the waxing crescent Moon will pass right across the cluster’s core, occulting most of the brighter members. Conditions for this are ideal for the UK, the occultation beginning at the start of the month when the Pleiades still have a decent altitude as darkness falls. For example, on 1 April at 21:00 BST (20:00 UT) under darkening twilight, the Pleiades are 30° above the western horizon. At the end of the month, under…

Alioth (Epsilon (ε) Ursae Majoris) is easy to locate as it’s one of the seven stars that form the famous Plough or Saucepan asterism. Imagining the pattern as a saucepan, mag. +1.8 Alioth is the first star in the handle away from the edge of the pan. Although in one of the more minor positions in the pattern, it may come as a surprise that Alioth is actually the brightest star in the Saucepan, albeit only beating Dubhe (Alpha (α) Ursae Majoris) by 0.3 magnitudes. ‘Alioth’ translates as ‘the sheep’s fat tail’. Alioth has a spectral type of A1III-IVp kB9, a long string of characters that needs some explanation. The ‘A1’ part indicates that it’s a star that appears white in colour. The ‘III–IV’ indicates that it’s regarded as being…

Since way back in the mid-1800s, both scientists and amateur observers have been keeping records of sunspots and, over time, a pattern began to emerge. The frequency of sunspots that appear on the Sun rises and falls cyclically over an 11-year period known as the solar cycle. The Sun is currently in Solar Cycle 25, which means this is the 25th cycle since records began. It is also at solar maximum, which is why the Sun is so active at the moment and also why we’re seeing increased aurora displays around the world. Solar cycles can be large or small, and normally a few large cycles are followed by a few small cycles. At the peak of solar cycles, the frequency of solar flares and coronal mass ejections, as well…

While astronomers don’t yet know what dark energy really is, it seems it will continue to drive the accelerating expansion of the Universe. One day, the space between stars will be stretched so much that galaxies are torn apart. Then the expanding space between planets will shred entire solar systems. Eventually, the space between electrons and atomic nuclei will be dragged out to such a degree that even atoms can no longer exist. Astronomers call this calamity the Big Rip. In around 22 billion years’ time, the Universe will contain no stars, planets, atoms or lifeforms – an empty, barren cosmic wasteland. This only happens, though, if dark energy continues to be ever more potent. If instead the Universe continues to expand at a steady rate, then we’re looking at…

Solar photography may feel out of reach to many, because viewing or imaging the Sun often involves specialist equipment. Solar telescopes have special coatings to block a large percentage of unwanted light from reaching your eye or your camera sensor. These can be combined with etalons, hydrogen-alpha (Ha), calcium-K (CaK) or white-light filters that allow you view the light emitted by certain elements. However, because of their specialist nature, all of these items tend to come with a high price tag. But there is a simple, cost-effective way to retrofit your telescope or camera lens to make it Sun-friendly: a DIY solar filter. For this, we use solar safety film, a special film that blocks enough light to allow you to safely view or photograph the Sun. The sheet of…

PHOTO OF THE MONTH △ The Dolphin Head Nebula Djaffar Ould Abdeslam, Lozere, France, 29–31 December 2024 Djaffar says: “This was a challenging target due to its faint luminosity and low position, just 20° above the horizon. That heightened the difficulties caused by denser atmospheric layers and increased turbulence, and reduced the window of visibility. I was very pleased to achieve this result over three nights.” Equipment: ZWO ASI2600MM camera, Askar FRA500 refractor, Sky-Watcher EQ6-R mount Exposure: Ha 24x 600”, OIII 53x 600” Software: NINA, PixInsight Djaffar’s top tips: “Faint objects near the horizon require long exposure times and careful polar alignment. Using narrowband filters to capture the Ha and OIII wavelengths is essential if you want to reveal fine details. A focal length of 250–400mm (this image was 350mm)…

What is Bennu? Bennu is a ‘rubble pile’ asteroid, almost spherical in shape but with a bulging belt. It’s about half a kilometre wide. It’s formed from reassembled fragments from a parent asteroid that was disrupted by an impact in the early Solar System. The pieces would have flown all over the place, reassembling into bodies like Bennu. Fortunately, Bennu’s orbit brings it close to Earth, so we could more easily venture there to get a sample. What exactly was the OSIRIS-REx mission? It was a sample-return mission. We sent a probe to Bennu to collect a sample that was brought back to Earth. These missions are challenging and complex but have amazing advantages. For example, when you get a sample back, you can study it with any instrument you…