Welcome back, and thanks for spending another evening here. Tonight we have sixteen stops, and many of them turned out to be something other than what they first seemed.
We'll visit the leftovers of a star that medieval astronomers watched explode, meet a moon shaped like an egg, find a galaxy as big as the Large Magellanic Cloud that nobody noticed, discover that the first known brown dwarf was really two, and look at the newest big crater on the Moon. At the end, we'll go back to the very first chemical bond the universe ever made.
Get comfortable. 🌙
1. 💥 Pa 30 is what's left of a star people saw explode in 1181
In early August 1181, Chinese, Japanese and Arabic astronomers recorded a new star in Cassiopeia. Eight separate texts describe it. It stayed visible for 185 days, then faded. SN 1181 is one of only five supernovae in our galaxy that were seen before the telescope was invented.
For centuries, nobody could say what it left behind. Then, in 2013, amateur astronomer Dana Patchick was searching infrared survey images for faint nebulae and found his 30th: Pa 30, a round shell threaded with straight filaments, like a frozen firework. Its age and brightness make it the likely remnant of SN 1181.
Pa 30 is unlike any other supernova remnant. Its central star is about 200,000 °C and blows a wind at around 16,000 kilometers per second. It sits almost exactly in the middle of the shell, so the explosion probably didn't kick it away. Astronomers think SN 1181 was a rare, incomplete explosion called a Type Iax supernova, one that failed to destroy its star.
In October 2026, new images from Gemini North showed that those firework streaks are really chains of tiny knots.
A star went off in 1181, and somehow it's still there, glowing in the middle of its own fireworks.
2. 🪐 Seven scorching planets have winds slowed by magnetism
Some giant planets orbit so close to their stars that one side is in permanent day and the other in permanent night. The temperature difference drives ferocious winds.
A team led by Julia Seidel measured those winds on seven of these hot, Jupiter-like planets, using the ESPRESSO instrument on the Very Large Telescope and a similar instrument on Gemini North. The speeds ranged from about 7,200 to over 25,000 kilometers per hour. Jupiter's fastest winds reach about 1,500.
Then came the surprise. The hotter the planet, the slower the wind. That's backward, because a hotter atmosphere has more energy to push its winds around.
The explanation the team found most consistent is magnetism. A planet-wide magnetic field can act like a brake, slowing the electrically charged particles in the atmosphere. From the amount of braking, the team worked out field strengths about four times Saturn's, or about half of Jupiter's. Published in June 2026, it's the first robust measurement of magnetic fields on planets outside the Solar System.
Those fields might also power aurorae over worlds that are half in endless day and half in endless night. We found an invisible force on another planet by watching its weather slow down.
3. ⭐ Scholz's Star brushed past the Solar System 70,000 years ago
The nearest star to the Sun today is Proxima Centauri, 4.2 light-years away. But about 70,000 years ago, a much closer visitor passed by.
Scholz's Star is a dim red dwarf with a brown dwarf companion, now about 20 light-years away in the constellation Monoceros. In 2015, Eric Mamajek and colleagues noticed something odd about it. It barely moves across our sky, yet it's moving almost directly away from us, and fast. That combination suggested it had recently come close.
Tracing its path back, the team found it passed about 0.8 light-years from the Sun, five times closer than Proxima is now. In 98% of their 10,000 simulated orbits, it went through the outer Oort Cloud, the vast swarm of icy bodies at the edge of the Solar System. Only one simulation sent it into the inner Oort Cloud, deep enough to trigger a shower of comets.
At its closest, it was still too faint to see with the naked eye. But it's a flaring star, and for minutes or hours at a time it may have brightened enough to be seen.
Our ancestors may have glimpsed it flicker. For a while, the Sun had a neighbor much closer than any star today.
4. 🧲 Hercules X-1 is a neutron star that wobbles like a thrown football
Hercules X-1 was only the second X-ray pulsar ever found. It's a neutron star that spins every 1.2 seconds, pulling gas off a companion star that it circles every 1.7 days.
It had a riddle. Every 35 days, like clockwork, its X-rays brighten and dim. The disk of gas around it seemed to block our view on that schedule, but for 50 years nobody knew what set the 35-day clock.
In 2024, NASA's IXPE telescope measured how the star's X-rays are polarized, and found the answer. The neutron star itself is wobbling once every 35 days. Think of a spiral pass that isn't quite perfect: the football wobbles because it doesn't spin exactly around its symmetry axis.
A neutron star is about 13 kilometers in radius and very nearly round. To wobble on this schedule, its shape only has to be off by about one part in 2.5 million. Even so, the spin axis wanders several kilometers across its surface every cycle.
Left alone, the wobble should die out within about a century. The gas falling onto the star keeps it going. A star the size of a city is wobbling, and its disk wobbles along with it.
5. 🌙 Methone is a moon shaped like an egg and smooth as one
Small moons are usually lumpy. "When we look at objects less than 200 kilometres in radius, they are all like potatoes," said planetary scientist Peter Thomas. They're covered in craters, grooves and boulders.
Then there's Methone. This tiny moon of Saturn, only a few kilometers across, was discovered in Cassini images in 2004. When Cassini finally got a close look in 2012, it saw a smooth, shiny egg with no visible craters at all.
Why? Thomas and his colleagues assumed that Saturn's tides had stretched the moon into its oval shape, and worked out how dense it would need to be for its own gravity to balance that stretch. The answer was about 300 kilograms per cubic meter, less than a third the density of water, and lower than any other known moon or asteroid.
So Methone may be made of something like fluff. Loose material that light might slowly flow and fill in craters. Charged ice grains could help too, but that's still a guess.
Methone orbits between Mimas and Enceladus, taking 24 hours per lap. It's a moon so soft that it may smooth away its own scars.
6. 🌌 Antlia 2 is a ghost galaxy hiding behind the Milky Way
In 2018, astronomers searching data from ESA's Gaia satellite noticed a group of RR Lyrae stars, old stars that pulse twice a day, sitting above the disk of the Milky Way. No known object was there.
Follow-up spectra of more than 100 red giants showed they were all moving together. It was a new dwarf galaxy, now called Antlia 2, and it's enormous: about as big as the Large Magellanic Cloud, the biggest galaxy orbiting ours.
Yet it's 10,000 times fainter than the Large Magellanic Cloud. It hid for so long because it's spread so thin, and because it sits behind the crowded disk of our own galaxy. "This is a ghost of a galaxy," said lead author Gabriel Torrealba.
It also seems to have less mass than a galaxy that size should. The Milky Way's tides may be stripping it, but galaxies that lose mass that way should shrink, not swell. So either Antlia 2 was born huge, or its dark matter behaves differently from what the leading theory predicts.
It might not be the only one. There could be more ghosts circling us that we simply haven't seen.
7. 🕳️ LID-568 is a young black hole eating far faster than it should
Every black hole has a speed limit on how fast it can feed, called the Eddington limit. Gas spiraling in gets so hot that its light pushes outward. Feed it faster, and that pressure should push the incoming gas away.
LID-568 seems to ignore that. It's a supermassive black hole seen just 1.5 billion years after the Big Bang, and it appears to be feeding at more than 40 times its Eddington limit.
Hyewon Suh's team at NSF NOIRLab found it in a group of galaxies that shine brightly in X-rays but are invisible in visible and near-infrared light. They used the James Webb Space Telescope's integral field spectrograph, which records a spectrum for every pixel of the view. That turned up powerful outflows of gas around the black hole, which may be acting as a release valve for all that extra energy.
The outflows also suggest that much of the black hole's mass may have built up in a single, rapid feast.
That matters, because astronomers have struggled to explain how black holes got so big so early. LID-568 shows that one way is to briefly eat far more than seems possible.
8. 🌑 McGetchin is the newest big crater on the Moon
In October 2025, Robert Wagner was running a routine check on a giant map of the Moon. He works with images from NASA's Lunar Reconnaissance Orbiter, and his software compares old images with new ones, turning anything unchanged gray.
One bright spot with a dark halo made him stop. "I just stopped, dropped everything, and started looking into what that spot was," he said.
It was a new crater, and the largest newly formed crater ever found anywhere in the Solar System. Now named McGetchin, it formed on the Moon's eastern edge sometime between April 11 and May 22, 2024, when a rock perhaps the size of a three- to six-story building slammed into the surface. The crater is about 220 meters wide and 43 meters deep.
Scientists think impacts this big happen on the Moon about once a century, or even less often.
The impact also changed the ground around it. A region about 6 kilometers wide is about 9 °C colder at night than its surroundings, because the blast fluffed up the soil and it holds less heat.
Most of us were going about our lives that spring. Meanwhile, the Moon took a once-in-a-century hit and nobody noticed for over a year.
9. 🟤 Gliese 229B, the first known brown dwarf, turned out to be twins
Brown dwarfs sit between stars and planets: too small to shine by fusing hydrogen like the Sun, but much heavier than Jupiter. The first one confirmed was Gliese 229B, found in 1995 at Palomar Observatory orbiting a small red star. Methane in its spectrum, a gas planets have but stars don't, gave it away.
Hundreds of papers followed, and one puzzle never went away. Its mass came out to about 70 times Jupiter's, but it was too dim for that.
In 2024, astronomers used two instruments on the Very Large Telescope to look closer. One combined four telescopes to split the image, and the other caught the light shifting as one part moved toward us while another moved away. It's two brown dwarfs, about 38 and 34 times Jupiter's mass, orbiting each other every 12 days.
They're only 16 times farther apart than Earth and the Moon, and each is smaller than Jupiter. Together they circle their star every 250 years. How such a tight pair forms is still a mystery.
For nearly 30 years, the textbook example of a brown dwarf was really two of them, holding hands too tightly to tell apart.
10. 💥 AT2018cow flared too bright and too fast to be a normal supernova
On June 16, 2018, the ATLAS survey telescope in Hawaii caught a sudden flash in a galaxy about 200 million light-years away, in Hercules. Its automatically assigned name ended in the letters "cow," so astronomers called it the Cow.
It didn't behave like a normal exploding star. It brightened over just a few days, and at its peak it was at least 10 times brighter than a typical supernova. Then it faded within months.
Astronomers turned telescope after telescope toward it, and still couldn't agree. One team suggested a black hole had shredded a star, maybe a white dwarf. Another thought a star had exploded and given birth to a black hole or neutron star, which would mean we'd caught a compact object being made in real time.
The Cow turned out to belong to a rare family called fast blue optical transients. They're so hot they glow blue, and so far bright ones like the Cow have turned up only in small galaxies. "These have probably been inside our archives for a long time," said astronomer Raffaella Margutti, describing how they used to be dismissed as "weird supernovae."
Some explosions don't fit any label yet. The Cow showed us there are new kinds still waiting to be named.
11. 🌌 COSMOS-z3.1-A is the ancestor of a cluster of clusters
Galaxy clusters are the heaviest objects held together by gravity, with hundreds or thousands of galaxies each. Sometimes clusters gather into even bigger families called superclusters.
Astronomers can watch these giants being built by looking far back in time. A team led by Vandana Ramakrishnan, then a graduate student at Purdue University, used the Dark Energy Camera in Chile to find 150 young clusters in the making, then mapped two of them in 3D with spectrographs, including DESI, which can measure 5,000 galaxies at once.
One of them, COSMOS-z3.1-A, turned out to be rarer still. It's a proto-supercluster, the seed of a cluster of clusters, seen when the universe was only 2.1 billion years old. That makes it the most distant one ever found. It has about 5,000 times the mass of the Milky Way, and there may be fewer than one like it for every 10,000 galaxy clusters.
The 3D maps show it's clumpy and irregular, sitting where several filaments of the cosmic web cross. That fits the idea that big structures grow from small ones merging.
Across more than 11 billion years of time, we're watching a city of galaxies still being built.
12. 🪐 TOI-6894b is a giant planet that shouldn't have formed around its star
The usual recipe for a giant planet starts with a solid core. It sweeps up material in the disk around a young star until it's heavy enough to pull in huge amounts of gas. Small stars have small disks, so they shouldn't have enough material to build giants.
TOI-6894 is a small red dwarf with only about 20% of the Sun's mass. Yet Edward Bryant, searching NASA TESS data on more than 91,000 small red dwarfs, found a giant planet circling it. TOI-6894b is a little wider than Saturn, with about half Saturn's mass. Its star is the lowest-mass star known to have a giant planet crossing in front of it.
Neither leading theory, a slowly growing core or a disk collapsing under its own gravity, fully explains it.
The planet is also cool for a giant, around 420 kelvin, or about 150 °C. Its air is expected to be dominated by methane, and it might even show ammonia, which has never been detected in an exoplanet atmosphere.
Most stars in our galaxy are small red dwarfs like this one. If they can make giants, there may be far more giant planets out there than we thought.
13. 🌙 The Moon has bright swirls where magnetic shields stand
On the Moon's dark plains there's a bright, swirling marking called Reiner Gamma. It looks like spilled cream. There's no mountain or crater to explain it. It's simply lighter soil, as if painted on the surface.
Lunar swirls like this one have puzzled scientists since the Apollo era. One clue is that every swirl sits on a patch of magnetized crust, though not every magnetic patch has a swirl.
Ideas have included fresh material from recent comet impacts and dust sorted by magnetism. A leading explanation is shielding. The Moon has no global magnetic field, so the solar wind, a stream of charged particles from the Sun, slowly darkens its soil. A strong magnetic patch can form a mini-magnetosphere, a tiny bubble that deflects the solar wind and keeps the ground beneath it bright.
In 2018, researchers simulated the solar wind hitting the magnetic field at Reiner Gamma. The pattern of shielding reproduced the swirl's shape. The details, including why some magnetic patches have swirls and others don't, are still debated.
There are places on the Moon where a tiny magnetic shield has been holding off the Sun for ages.
14. 👻 Shadow Blaster may be a galaxy shooting ghost particles at us
Neutrinos are ghostly particles. They have almost no mass and barely interact with anything, so huge numbers pass straight through you every second. The rare high-energy ones come from deep space, and finding their sources is hard. A few have been traced to violent places, such as jets from giant black holes.
On September 22, 2021, the IceCube Neutrino Observatory in Antarctica caught one from the direction of Eridanus. Telescopes searched the area and found no explosion, no flash and no feeding black hole.
A few days after the alert, Yuji Urata's team found a very bright, dusty galaxy in the area and nicknamed it Shadow Blaster. It's about 11 billion light-years away, and a galaxy in front of it acts as a lens, magnifying it. Their analysis, published in June 2026, found a compact core packed with gas and dust, making stars at a furious rate, and no sign of an active black hole.
Theory says such crowded star factories can act as natural particle accelerators. If the link holds, galaxies like it might make up to about 20% of the high-energy neutrinos IceCube sees.
It's not confirmed yet. But some ghost particles may come not from black holes, but from the frantic birth of stars.
15. 🌌 The Milky Way's center glows with gamma rays nobody can explain
NASA's Fermi Gamma-ray Space Telescope sees gamma rays, the most energetic light there is, across the whole Milky Way. Most of it has known sources. But around the center of the galaxy there's an extra glow, extending about 5,000 light-years in every direction. It's called the Galactic Center Excess.
There are two leading suspects. One is a huge population of old, fast-spinning pulsars, each too faint to see separately. The other is far more exciting: particles of dark matter colliding and destroying each other.
In 2015, a team including Tracy Slatyer found the glow looked grainy, as you'd expect from many separate pulsars, rather than smooth like dark matter. Then in 2019, Slatyer and Rebecca Leane tested their own method. They added a fake dark matter signal to the real data, even one four times stronger than the actual excess, and the method still said "pulsars." "It reopens the door," Slatyer said.
Shape is another clue. In 2025, a study using simulated Milky Way-like galaxies found that a dark matter glow wouldn't be round either, so shape alone may not settle it. Telescopes that see even higher-energy gamma rays should help tell the two apart.
Either way, something at the center of our galaxy is glowing, and we still don't know what.
16. 🧪 HeH⁺ was the universe's first molecule, and we finally found it
For a long time after the Big Bang, the universe was too hot for atoms to hold on to electrons. As it cooled below about 4,000 kelvin, helium caught electrons first and became the first neutral atom. Hydrogen was still just bare protons.
Then the two met. A helium atom and a proton joined to form helium hydride, HeH⁺, the universe's first molecular bond. Every molecule since, from water to DNA, came later.
Chemists made HeH⁺ in the laboratory as early as 1925, and astronomers searched for it in space for decades without success. Its strongest signal is at a wavelength our atmosphere blocks. So in 2019, a team led by Rolf Güsten used SOFIA, a Boeing 747 carrying a telescope above most of the atmosphere, and pointed it at the planetary nebula NGC 7027. There, around a dying star hotter than 100,000 degrees, conditions are right for the molecule to form again. They found it.
This HeH⁺ isn't left over from the Big Bang. It was made recently, around that dying star, but it's the same simple bond the young universe formed first.
Chemistry began with one fragile molecule, and we found it again in the glow of a dying star.
🌙 One last thought before you sleep
So many of tonight's stories were about mistaken identity.
The first known brown dwarf was two. A smudge in infrared images was the remains of a star that people watched explode more than 800 years ago. A crowd of pulsing stars was a whole galaxy no one had noticed, and an odd, smooth moon is probably made of something like fluff. Even the glow at the center of our galaxy might be thousands of pulsars, or something much stranger.
It's humbling, and also a little comforting. Astronomers get things wrong, then look again with better tools and get them a little more right.
And underneath it all is the simplest thing: one atom of helium and one proton, finding each other in the cooling dark, and starting the long story of chemistry that led, eventually, to you.
Every bond in your body has a first ancestor, and it's still out there to be found.
That's all for tonight. Thanks for wondering along with me. Good night, and clear skies. 🌌
— Kasi