Is the Star Manual of Master Shi the oldest known astronomical catalog? Experts are divided.
The oldest star chart in the world was made in China more than 2,300 years ago, a hotly debated preprint study finds.

Researchers at the Chinese National Astronomical Observatories analyzed the "Star Manual of Master Shi," the oldest surviving star catalog in China, using a novel digital image processing technique. The method, called Generalized Hough Transform, uses a type of artificial intelligence known as computer vision to find and mitigate significant errors between similar images.

They found that the ancient star chart actually dates to 355 B.C. — 250 years earlier than previously thought — and that it was later updated around A.D. 125. This would make it the oldest-known star catalog of its kind in the world, predating a star chart by ancient Greek astronomer Hipparchus by more than 200 years.

"I think this is pretty definitive,"said David Pankenier, a professor emeritus of Chinese astronomy at Lehigh University in Pennsylvania who was not involved with the research. Pankenier told Live Science that the study confirms previous research — notably, the work of Joseph Needham, a British biochemist known for his expertise on ancient Chinese science and technology. And the new study places the manuscript's origin around the same time the historical Master Shi Shen was thought to have lived.

But other experts are less convinced.

On Earth, the most dangerous tornadoes are rated F5. On the sun, they can be hundreds of times worse. David Wilson photographed this twister, big enough to swallow our entire planet, from his backyard observatory in Inverness, Scotland:

"I was recording this monster all day on April 24th when I noticed the central stem grow brighter until it let go at about 1300UT," says Wilson. "It looked like a huge swirl of plasma went round the stem and flew into space."

A massive black hole at the heart of a galaxy in the Virgo constellation is waking up, shooting out intense X-ray flares at regular intervals that have puzzled scientists, a study said Friday.

Astronomers previously had little reason to pay any attention to galaxy SDSS1335+0728, which is 300 million light years from Earth. But in 2019, the galaxy suddenly started shining with a brightness that turned some telescopes its way.

Then in February last year, Chilean astronomers started noticing regular bursts of X-rays coming from the galaxy.

This was a sign that the galaxy's sleeping black hole was waking from its slumber, according to the study published in the journal Nature Astronomy.

Most galaxies, including our home Milky Way, have a supermassive black hole squatting at their heart, like a spider in a web.

These invisible monsters gobble up everything that comes their way — not even light can escape their almighty suck.

If an unlucky star swings too close, it gets torn apart.

The star's shattered material becomes a stream that spins rapidly around the black hole, forming what is called an accretion disk that is gradually swallowed.

But black holes can also go through long periods of inactivity when they do not attract matter.

And after a fairly uneventful period, the bright, compact region at the heart of galaxy SDSS1335+0728 has been classified as an "active galactic nucleus" — and given the nickname "Ansky".

"This rare event provides an opportunity for astronomers to observe a black hole's behavior in real time" using several X-ray telescopes, astronomer Lorena Hernandez-Garcia of Chile's Valparaiso University said in a statement.

A new nova for early risers plus three fun observing projects for the week ahead.

We have a new "star" in the night sky. In truth, it's been there for billions of years, but it only first revealed itself a little more than a week ago. Nova Sagittarii 2025 no. 3 was independently discovered on March 23-24 by the Russian New Milky Way (NMW) Survey and Japanese amateur Tadashi Kojima at a right ascension of 18h 02′ and declination of -33° 11′. Both parties caught the star around magnitude 13; two days later it had brightened to 10.5. Despite its southerly declination, the nova stands more than 10° above the horizon before the start of dawn, making it an attainable target even for observers in the northern U.S.

Clouds have thwarted my attempts to see it, but most estimates posted to the AAVSO peg it at magnitude 10.7 on April 1st. Not long after its discovery, the star received the official designation V7993 Sagittarii, making it the 7,993rd variable star to be discovered in Sagittarius. Although novae can appear anywhere in the sky, they're far more common within the star-dense band of the Milky Way, and especially in Sagittarius where we face toward the galactic center. In fact, this is the third nova discovered so far this year in the constellation.

The most dangerous parts of a supernova explosion are the outputs like X-rays and gamma rays. Even though they only share a small fraction of a supernova's power, they are extremely dangerous. But they're not going to disintegrate the Earth. We are simply too far away from any potential supernova for that to ever be a problem.

What can happen is that these forms of radiation pack enough energetic punch that they can tear apart molecules. Elements like nitrogen and oxygen prefer to float around as molecules in our atmosphere. But then once they get hit by x rays, gamma rays, and cosmic rays, they get broken apart. And then they recombine in interesting and fascinating ways like various nitrogen oxides, including everybody's favorite nitrous oxide AKA laughing gas. And while everyone's laughing and having a good time, our ozone layer gets stripped away.

That's the danger of a too-close supernova: it breaks up our ozone layer. And without an ozone layer, it means the Earth is vulnerable to ultraviolet radiation from the Sun. Our ozone layer protects us from the vast majority of ultraviolet radiation. There are a couple specific bands of wavelengths that do sneak through, which is why we need to wear sunscreen here on the surface, so we don't get nasty tans and sunburns and skin cancer and all that.

But imagine no ozone layer, then you get all the UV radiation, the full output, and it's bad. And it's not just a matter of quicker tans and faster burns and higher rates of skin cancer. The problem is that photosynthetic microorganisms like algae become vulnerable. They get cooked and then they die. And since they form the very base layer of the food chain, you end up with whole ecosystem collapse and a mass extinction.

The race between Jupiter and Saturn for the most moons in the Solar System may have just finally come screeching to a halt.

A team of scientists has found a whopping 128 previously unknown moons hanging around Saturn, in a discovery officially recognized by the International Astronomical Union. This brings the planet's total number of known moons to 274, leaving Jupiter, with its mere 95 moons, in the dust.

The first hint that there were more moons awaiting discovery came between 2019 and 2021, when 62 such objects were identified. Other small objects were also spotted at the time that couldn't yet be designated.

"With the knowledge that these were probably moons, and that there were likely even more waiting to be discovered, we revisited the same sky fields for three consecutive months in 2023," says astronomer Edward Ashton of Academia Sincia in Taiwan.

"Sure enough, we found 128 new moons. Based on our projections, I don't think Jupiter will ever catch up."

An international team of astronomers has investigated a newly detected Type II supernova designated SN 2024jlf. The new study, detailed in a paper published Jan. 30 on the arXiv pre-print server, yields important information regarding the evolution of this supernova and the nature of its progenitor.

Type II supernovae (SNe) are the results of rapid collapse and violent explosion of massive stars (with masses above 8.0 solar masses). They are distinguished from other SNe by the presence of hydrogen in their spectra.

Based on the shape of their light curves, they are usually divided into Type IIL and Type IIP. Type IIL SNe show a steady (linear) decline after the explosion, while Type IIP exhibit a period of slower decline (a plateau) that is followed by a normal decay.

SN 2024jlf was first spotted on May 28, 2024 using the Zwicky Transient Facility (ZTF), with a brightness of 15.88 mag. The supernova occurred in NGC 5690 — an edge-on spiral galaxy at a redshift of 0.0058.

Subsequent observations of SN 2024jlf after its discovery have revealed that its spectrum shows a blue continuum with weak flash features, indicating a young core-collapse supernova of Type II. A search for the progenitor of SN 2024jlf has also been conducted. However, no source has been identified in the location of this supernova.

Chorus waves are mysterious, chirping signals produced by spiraling plasma inside our planet's magnetic field. But a new detection suggests scientists may understand less about them than first thought.
Scientists have detected strange chirping waves — which resemble the dawn chorus of birds — thousands of miles from Earth, and they could pose big problems for future spaceflight.

Chorus waves, named because of their resemblance to birdsong when converted to audio signals, are perturbations in Earth's electromagnetic field capable of accelerating particles to potentially deadly speeds for spacecraft and astronauts.

Yet while these mysterious waves have been spotted coming from Earth and other planets since the 1960s, scientists previously assumed they only occurred nearby.

Now, in a discovery that challenges existing theories, a new team of researchers has spotted the waves at a distance of 100,000 miles (165,000 kilometers) from Earth, roughly three times further than they were detected before. The researchers published their findings Jan 22. in the journal Nature.

Chorus waves (or whistler-mode chorus waves) are bursts of energy lasting just a few tenths of a second that ping across Earth's magnetosphere, the magnetic field that envelops our planet. The waves were first detected by World War I radio operators who heard them while listening for enemy signals.

In the decades since, chorus waves have been picked up by radio receivers, as well as by NASA's Van Allen Probe spacecraft, which detected the chirrups coming from Earth's radiation belts. The waves have also been spotted surrounding Mercury, Jupiter, Saturn, Uranus and Neptune (all planets with global magnetic fields) as well as Mars and Venus, which do not have magnetic fields.

The new ability to pinpoint sources of fast radio bursts places one recent burst in a surprising location.
Astronomer Calvin Leung was excited last summer to crunch data from a newly commissioned radio telescope to precisely pinpoint the origin of repeated bursts of intense radio waves — so-called fast radio bursts (FRBs) — emanating from somewhere in the northern constellation Ursa Minor.

Leung, a Miller Postdoctoral Fellowship recipient at the University of California, Berkeley, hopes eventually to understand the origins of these mysterious bursts and use them as probes to trace the large-scale structure of the universe, a key to its origin and evolution. He had written most of the computer code that allowed him and his colleagues to combine data from several telescopes to triangulate the position of a burst to within a hair's width at arm's length.

The excitement turned to perplexity when his collaborators on the Canadian Hydrogen Intensity Mapping Experiment (CHIME) turned optical telescopes on the spot and discovered that the source was in the distant outskirts of a long-dead elliptical galaxy that by all rights should not contain the kind of star thought to produce these bursts.

Instead of finding an expected "magnetar" — a highly magnetized, spinning neutron star left over from the core collapse of a young, massive star — "now the question was: How are you going to explain the presence of a magnetar inside this old, dead galaxy?" Leung said.

The young stellar remnants that theorists think produce these millisecond bursts of radio waves should have disappeared long ago in the 11.3-billion-year-old galaxy, located 2 billion light years from Earth and weighing more than 100 billion times the mass of the sun.

This NASA/ESA Hubble Space Telescope Picture of the Week features the galaxy LEDA 22057, which is located about 650 million light-years away in the constellation Gemini. Like the subject of a previous Picture of the Week, LEDA 22057 is the site of a supernova explosion.

This particular supernova, named SN 2024PI, was discovered by an automated survey in January 2024. The survey covers the entire northern half of the night sky every two days and has cataloged more than 10,000 supernovae.

The supernova is visible in the image: Located just down and to the right of the galactic nucleus, the pale blue dot of SN 2024PI stands out against the galaxy's ghostly spiral arms. This image was taken about a month and a half after the supernova was discovered, so the supernova is seen here many times fainter than its maximum brilliance.