Researchers may have spotted the first signs of a dark matter particle. If the result is confirmed, it could be one of the most monumental discoveries in the history of physics.

Dark matter makes up about 85 per cent of matter in the universe, but for decades physicists have been unable to determine what it itself is made of. Hypotheses have ranged from different sorts of particles and forces to strangely behaving gravity and everything in between – but the leading idea has always been that of the weakly interacting massive particle, or WIMP. As we have built more and more powerful detectors to search for WIMPs, though, their failure to show up has led many to doubt their existence and move on to more exotic ideas.

That doubt may soon come to an end. A new analysis of data from the LUX-ZEPLIN (LZ) experiment in South Dakota has revealed a single particle that may be the first WIMP ever detected. “This result is certainly an exciting one, because it provides some potential positive hint for what dark matter could be, not just what dark matter could not be,” says at Brown University in Rhode Island, who wasn’t part of the analysis.

LZ looks for dark matter using a 7-tonne tank of liquid xenon, surrounded by several layers of shielding and buried more than a kilometre down to keep out other types of particles. When an outside particle hits a xenon atom, it creates a tiny burst of light that is measured by sensitive detectors surrounding the tank. Researchers can then use that light to reconstruct the path of the incoming particle and the energy level of the interaction.

In the search for WIMPs, we generally look for events with energies below about 30 kiloelectronvolts (keV), says LZ spokesperson , also at Brown University. That assumes the simplest sort of interaction, in which the WIMP is essentially bouncing off an individual nucleon in the xenon nucleus. Having not found any hints of WIMPs in that energy range, the LZ team decided to reanalyse the first 220 days of data from the detector, searching for events with higher energies.

That is where they found their dark matter particle candidate, at about 248 keV. “You must never make an assumption that nature is going to do something the easy way,” says Gaitskell. “Nobody can accuse our universe of making the simplest and most natural-seeming choices.”

Such a high-energy event can’t have come from the most simple type of interaction between a WIMP and a nucleon – instead, it must have happened through a more complicated coupling between the WIMP and the entire xenon nucleus. If that is the case, the WIMP must have a mass more than 200 times the mass of a proton.

“It’s not just that they’re seeing something, but that there’s a hint at what the underlying mechanism might be,” says at the University of California, Berkeley, who wasn’t involved in the analysis. “If this all stands up, our learning curve is going to be pretty steep from now on.”

Actually detecting a dark matter particle could reveal some of the universe’s most closely held secrets, including information about the early universe that is otherwise nearly impossible to determine, and drastically shake up our standard model of particle physics. But as Haxton says, this detection is not yet certain.

In particle physics, the statistical threshold for a finding to go from an intriguing hint to a solid discovery is a number called 5 sigma, which means there is about a 1-in-3.5 million chance that a signal like this would show up as a fluke rather than a true sign of dark matter. Right now, this detection from LZ sits at 2.6 sigma, which means that there is about a 1-in-200 chance it could appear as a fluke.

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That might still seem fairly secure, but in the search for dark matter it is far from enough. “In science we sit down and we do so many damned experiments, I’m afraid you come across a 1-in-100 event fairly often,” says Gaitskell.

“Before one can declare victory, you need a few more data points, but now they have something to aim for, they know where to look,” says Haxton. The good news is that this analysis only covered about one-third of the data that LZ has already taken, and other dark matter detectors around the world have their own data, as well. A few more events in the same energy range could bump the discovery of WIMPs up to 5 sigma – and change our understanding of physics and the universe forever.

A star near the centre of the Milky Way is hurtling through its orbit with a peak speed of more than 8 per cent the speed of light, making it both the fastest star and the closest to a supermassive black hole that has ever been spotted. Named S301, this astonishing star could help us unravel the secrets of gravity.

at the Max Planck Institute for Extraterrestrial Physics in Germany and his colleagues found S301 using the Very Large Telescope in Chile. They have been watching it since 2023 to get enough data to pin down its orbit, and the results are unprecedented.

At its closest approach, S301 is only about 1.8 billion kilometres from Sagittarius A*, the supermassive black hole at the centre of our galaxy. That’s just 12 times the distance between Earth and the sun, 10 times closer to Sagittarius A* than the previous record-holder. “If you were living on a planet around this star, the size of the black hole at the closest approach would appear similar to the full moon from Earth – it would be absolutely stunning,” says Gillessen.

Such a close pass by the black hole means that S301 spends part of its orbit in one of the most extreme gravitational environments in the universe. Next to a black hole, space-time stretches and warps. If a black hole is spinning, it should warp space-time even more, twisting it up in what is known as the frame-dragging effect.

“Earth does this as well, and we can measure with satellites around Earth that there is a very, very slight frame dragging from Earth’s rotation,” says at the University of California, Los Angeles, who wasn’t involved in the research. “This is doing the same thing, just with much different objects.”

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Measuring Earth’s spin is relatively easy, but a black hole’s spin is much harder to determine because of its lack of a visible surface. The most precise way to measure it would be by measuring frame dragging, and S301 is the first star close enough to feel that effect.

“We drop a leaf in the wind and see how the air is moving by measuring that leaf,” says Gillessen. “A star is just the perfect leaf to drop to see the movement of space-time.”

Actually measuring the spin of Sagittarius A* using this method will probably take around a decade, he says, but that may speed up if we find more stars like it.

“With one star, it would take a while, but it would still be the best constraint on spin that we’ve ever had by far,” says at University College London. “If you can find another star that’s even closer, that’s better still. If you can find a population of these stars, then you’re in business.”

Gillessen and his team have several candidates for stars slightly further from the black hole than S301, but none yet that are closer, he says.

But when we finally do measure the spin of a black hole, it will be a crucial piece of the cosmic jigsaw. It will not only help us understand how black holes have contributed to the evolution of the universe, but will also provide a probe into the behaviour of gravity in extreme environments, which has proved extremely difficult to study.

“A black hole only has three measurable properties: a mass, a spin and possibly an electric charge. The mass was worth a Nobel prize in 2020, so, if you find the spin, you might expect a call from Stockholm in 20 years,” says Gillessen.

On 12 August, a total solar eclipse will sweep across parts of Europe and the Atlantic ocean as the moon passes between Earth and the sun, blocking out sunlight. Parts of the US and Africa, along with the entire UK and much of Europe and Canada, will see a partial solar eclipse.

Where can I see the eclipse in the UK and US?

While the total eclipse will be short and only visible in a few areas, a partial eclipse, with the moon taking a “bite” out of the sun, will last much longer across about a quarter of the entire planet. It won’t be as dramatic as a total eclipse – the corona will not become visible, and the ambient light levels and temperatures won’t drop as dramatically – but will be watchable for many more people.

In the UK and Ireland, 90 to 96 per cent of the sun will be covered by the moon. In London, the eclipse will last from 6.17 to 8.06pm, with the maximum at 7.12. The sun will be setting, so you need to be somewhere with a clear view to the west.

In most of Canada, Alaska and the northeastern US, the moon will cover less than half of the sun. Montreal will get an 18 per cent eclipse at 1.45pm and New York will get a 9 per cent eclipse at 1.54pm.

Where can I see the total eclipse?

Totality, which occurs when the moon lines up perfectly with the disc of the sun and blocks it out entirely, will begin in Russia around midday before sweeping eastward across the Arctic ocean. It will pass just south of the North Pole and make landfall in northeastern Greenland just after 4.00pm local time.

The shadow will then rush along the eastern coast of Greenland at a speed of more than 3400 kilometres per hour. The maximum length of totality will be about 2 minutes and 18 seconds, as the moon’s shadow crosses from Greenland into the Atlantic ocean. It will cross to Iceland, at which point the eclipse will become visible from more heavily inhabited areas – everywhere it will have passed so far is home only to small villages, research stations and those specifically making the journey to see the eclipse. In Reykjavík, though, totality will be visible for just over one minute at 5.48pm local time. This is the first time a total eclipse has been visible in Iceland since 1954, and the last time one will be visible there until 2196.

After skimming the western coast of Iceland, the total eclipse will make another ocean crossing and reach land again in northern Spain just before 8.30pm local time, grazing the northeast corner of Portugal and crossing the Balearic Islands off Spain’s east coast before the sun sets and the eclipse is over.

How can I watch the eclipse safely?

During a total or partial eclipse, eye protection is needed the whole time. If you don’t have eclipse glasses, you can use a pinhole camera or even natural shadows to create a projection of the sun’s shape as the moon passes in front of it. Read this article for more details of how to do that.

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What happens during a total solar eclipse?

During totality, when the disc of the sun is completely concealed by the moon, temperatures on the ground rapidly drop by several degrees and daytime transforms into twilight. The stars and the outer reaches of the sun become visible. Usually, the sun’s outermost layer, the corona, is completely lost in the glare from its far brighter inner regions, but when those are blocked out, its shimmering sheets of extraordinarily hot plasma become briefly visible to the naked eye. In all other phases of the eclipse, it is crucial to wear eclipse glasses or use a solar filter while looking directly at the sun to prevent eye damage, but during totality it is safe to look at the corona.

That is precisely what many solar scientists will be doing during August’s eclipse. Total eclipses mark a valuable opportunity to observe the corona and try to unravel its many mysteries, including why it is so much hotter than the sun’s surface.

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During a solar eclipse, the shadow of the moon moves across the surface of Earth as the moon travels between our planet and the sun. Thanks to a cosmic coincidence – the fact that the sun is both about 400 times larger than the moon and about 400 times as distant – when the two line up just right, they appear the same size and the moon completely covers the disc of the sun in a total eclipse. 

Totality, the period in which the disc of the sun is completely hidden, is the only time when it is safe to look directly at the sun; otherwise, looking at the sun can burn your retinas and cause vision loss. But during a partial eclipse, or even when no eclipse is happening at all, you can still look at the sun – you just need proper eye protection or a clever trick to project its image so you don’t have to look directly at it. Here are four ways to look at the sun without burning your eyeballs.

1. Wear eclipse glasses

This is the safest way to view a solar eclipse, and the only one that actually involves staring straight at the sun. Regular sunglasses won’t do the trick: eclipse glasses are about 100,000 times darker, letting through only a tiny fraction of sunlight to protect your eyes.

Looking through a pair of eclipse glasses, or any other kind of proper solar filter, you shouldn’t be able to see anything but the sun – even the brightest indoor light should appear extremely dim. The American Astronomical Society has put together a list of trusted suppliers, which you can see .

If you aren’t sure about the safety of your eclipse glasses or if they don’t seem quite dark enough, stick with one of the other methods on this list. If you are looking through a telescope or binoculars, eclipse glasses won’t be enough to protect your eyes – make sure any magnifying device has a proper solar filter over its objective lens or lenses, which are the ones through which light enters the device.

2. Use the shadows

The easiest way to view a partial eclipse doesn’t require any special equipment at all. When light passes through a small opening, it projects the shape of whatever emitted it onto the next surface that it hits.

During a partial eclipse, this means you can use shadows to see how much of the sun is hidden behind the moon. Anything can create the small openings necessary for this: a colander, cheese grater, straw hat or even your outstretched hands with fingers creating a sort of grid shape.

Even just standing under a tree and looking at the shadows cast by the leaves can reveal a smattering of crescent sun shapes on the ground.

3. Pinhole projection

If you want to get a little bit more involved, you can use the same effect to create a pinhole projector, which is essentially just a surface with a tiny hole poked in it.

If you take a cardboard box and poke a small hole in one end with a pushpin or pen, the shape of the sun will be projected on the other end. All you have to do is face away from the sun with the hole pointing towards the sun and look down to the other end of the box (if you have a big enough box, you can even put your head inside – if not, you might have to cut a slot to look through in the same side as the hole) and the shape of the sun will be projected there.

Don’t look through the tiny hole, because your head will block the light that should be shining through it. Looking through the hole directly at the sun will still burn your eyes, so you should only look at the projection on the other end of the box.

4. Mirror projection

This projection method is similar to the others – the theme being, don’t look right at the sun – but may be easier if you want a large projection of the sun that lots of people can look at.

All you need is a small, flat mirror and some way of angling it so that it reflects the sunlight onto a flat surface such as a wall or screen. If you cover the mirror almost entirely using a sheet of paper or cloth with a small hole cut in the middle, it will work just like the pinhole projector to shine an image of the sun on the wall.

The smaller the hole is, the sharper the image will be, although it will get dimmer as less light shines through. But if you can get your image big or sharp enough, you might even be able to see any sunspots that happen to be pocking the sun’s face during the eclipse.

Once again, don’t look at the sun via its reflection in the mirror, which is just as dangerous as looking directly at it if you don’t have eclipse glasses on. Only look at the projection of the sun, and you will be able to enjoy the eclipse without any unnecessary visits to an ophthalmologist.

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Astronomers have spotted one of the strangest-looking asteroids we have ever seen. The space rock, called 44 Nysa, was discovered in 1857, but it wasn’t until now that we had the observational capability to figure out its shape – and its shape is weird.

An E-type asteroid, which is a relatively rare type rich in a mineral called enstatite, 44 Nysa circles the sun in the main asteroid belt between the orbits of Mars and Jupiter. It is the brightest E-type asteroid we know of and one of the largest, with an average diameter of about 75 kilometres, which makes it a tempting observational target.

at the Lowell Observatory in Arizona and her colleagues used the Large Binocular Telescope, also in Arizona, and the Very Large Telescope in Chile to take a closer look at 44 Nysa. They used that data to build a three-dimensional model of the asteroid, and found that it seems to have three lobes, each separated from the others by a thin “neck” that holds the asteroid together.

While two-lobed asteroids are relatively common, trinary ones are much rarer. It isn’t yet clear how exactly it formed – it could have once been a more normal-shaped asteroid and then been battered beyond recognition by other space rocks, or the three lobes could have once been separate and then joined together in what’s called a contact trinary. Either way, its interior must be strong to have stuck together.

Another wrinkle in the story is that 44 Nysa seems to have a tiny moon, just about a kilometre across. In future observations, measuring the moon’s orbit could give us more information about 44 Nysa’s interior structure, and therefore its origins.