Welcome back, and thanks for spending another evening here. Tonight we have fifteen stops, from a star that came back from the dead to a future that hasn't been decided yet.
We'll watch a dying star reheat within a single human career, meet a planet stretched into the shape of a lemon, follow a tiny asteroid that may be a piece of our own Moon, and look inside a red dot that might be a black hole wearing a star's disguise. At the end, we'll ask whether the Milky Way and Andromeda are really destined to collide.
Get comfortable. 🌙
1. ⭐ Sakurai's Object is a star living its old age twice
Stars like the Sun end quietly. They puff off their outer layers and shrink into white dwarfs. Sakurai's Object was well along that path when, in 1996, it suddenly flared back to life.
Astronomers think a layer of helium deep inside it reignited in a last burst of fusion, called a very late thermal pulse. The star swelled, cooled and threw off huge amounts of material, briefly returning to an earlier stage of its life.
Now it's heading back toward the end, and quickly. A study published in September 2026 used the Very Large Telescope to show that the star has become about six times hotter in 30 years, reaching an estimated 27,000–36,000 kelvin. It's also developing the fierce wind typical of Wolf-Rayet stars.
Interestingly, it's heating more gradually than some models predicted, and the dust it shed hides it from direct view. Only one other star, V605 Aquilae, has been seen going through a similar rebirth.
Stellar evolution usually takes millions of years. Here, a star is changing visibly within a single human lifetime.
2. ☄️ Arrokoth's two halves met at walking pace
On January 1, 2019, the New Horizons spacecraft flew past Arrokoth, a small, icy world in the Kuiper Belt more than 6 billion kilometers from Earth. It's about 35 kilometers long and made of two lobes stuck together.
The obvious guess was a collision. But the details, including the lobes' uniform color and composition, pointed somewhere gentler.
The team concluded that the lobes formed close together, orbited each other, and then slowly spiraled into contact. Both probably grew out of a cloud of solid particles in the early Solar System that collapsed under its own gravity.
That matters far beyond one small world. It suggests that the building blocks of planets didn't have to grow by smashing together at high speed. Mission lead Alan Stern said the evidence "all but rule[s] out" that older picture, at least for objects like Arrokoth.
Arrokoth has drifted almost untouched since then, a fossil from the gentle earliest days of planet building.
3. 🪐 PSR J2322−2650b is a planet stretched into a lemon
Some planets orbit the corpses of stars. PSR J2322−2650b has a mass similar to Jupiter's and circles a rapidly spinning pulsar only about 1.6 million kilometers away. Its year lasts 7.8 hours.
When the James Webb Space Telescope examined it, the results were baffling. Instead of the water, methane or carbon dioxide seen on most giant exoplanets, the atmosphere is dominated by helium and carbon, with clouds of soot and molecules made of just two or three carbon atoms.
The way its brightness changes around the orbit suggests that the pulsar's gravity has pulled the planet into a lemon shape. Deep inside, under enormous pressure, carbon could even crystallize into diamond, although that's a possibility rather than an observation.
How such a world formed is a puzzle. The lead researcher said its composition "seems to rule out every known formation mechanism." One idea involves carbon crystals rising and mixing into the helium, but something would still have to keep oxygen and nitrogen out.
It's a soot-clouded, lemon-shaped giant racing around a dead star, and nobody yet knows how it got there.
4. 🌌 Malin 1 is a galaxy too faint to notice and too big to imagine
Most galaxies are easy to spot because their stars are packed tightly enough to glow. Malin 1 is so diffuse that astronomers only found it in the 1980s.
It's a giant low surface brightness galaxy: an enormous disk with its stars spread so thinly that its light is extremely faint and diffuse.
Deep observations combining six wavelengths, from ultraviolet to near-infrared, traced its disk to a diameter of more than 250 kiloparsecs, over 800,000 light-years. The Milky Way's disk is about 30 kiloparsecs across, so Malin 1 is roughly eight times wider.
The same study modeled how its stars formed. The disk seems to have existed for several billion years, making stars at a slow and steady rate, rather than being assembled in some violent interaction.
Our galaxy would fit across Malin 1 several times over, and yet it took until the 1980s for anyone to notice it was there.
5. 🧲 M82 X-2 is a neutron star that shines like a black hole
In the Cigar Galaxy, M82, there's an X-ray source so bright that astronomers assumed it must be a black hole. It's one of the ultraluminous X-ray sources, objects that seem to break a basic rule.
That rule is the Eddington limit. As matter falls onto an object, it heats up and shines, and that light pushes outward on the incoming material. Beyond a certain brightness, the push should overpower gravity and choke off the supply. A heavier object can shine brighter before reaching that point.
Then, in 2014, NASA's NuSTAR telescope noticed that M82 X-2 pulses every 1.37 seconds. Black holes don't pulse like that. Spinning neutron stars do.
So this source was a pulsar, not a black hole, with a mass only a little more than the Sun's, orbiting a more massive companion star every 2.5 days. How it pulls in so much material and shines so brightly is still debated.
A dead star about the size of a city is out-shining what its own mass should allow.
6. 🪐 Fomalhaut's "planet" was dust, and now there's another one
In 2008, astronomers using Hubble announced what looked like a planet orbiting Fomalhaut, a bright star about 25 light-years away. Over the following years, Fomalhaut b faded and spread out. Many astronomers came to think it was never a planet at all, but a cloud of dust from a collision between two smaller bodies.
Then, in Hubble images from 2023, a new point of light appeared nearby, looking much as Fomalhaut b had two decades earlier. The team's leading explanation, published in Science in December 2025, is a second collision between planetesimals, asteroid-like building blocks of planets.
Theory had suggested such collisions should happen around Fomalhaut perhaps once every 100,000 years or longer. "Here, in 20 years, we've seen two," said lead author Paul Kalas.
The case isn't closed. A follow-up image in 2024 was poor, and the team plans to track the new cloud with Webb.
It's also a warning for planet hunters: a large dust cloud can masquerade as a planet for years.
7. ⭐ VFTS 352 is two giant stars touching
In the Tarantula Nebula, about 160,000 light-years away, two enormous stars orbit each other in a little over a day.
Together, the stars of VFTS 352 hold about 57 times the Sun's mass, and their surfaces are hotter than 40,000 °C. Their centers are only 12 million kilometers apart, so close that the stars actually touch. They share about 30% of their material, joined by a bridge of gas. Astronomers call this an overcontact binary.
What happens next is uncertain, and both endings are dramatic. The stars may merge into a single, rapidly spinning giant that could one day end as a gamma-ray burst. Or, if their insides are mixed well enough, they could each stay compact, explode separately, and leave behind a pair of black holes on a tight orbit.
That second ending would eventually produce exactly the kind of black-hole merger that gravitational-wave observatories detect.
Two stars that share a single skin may be rehearsing the birth of a pair of black holes.
8. 🌙 Kamoʻoalewa may be a piece of our Moon
Earth has a small companion that isn't quite a moon. Kamoʻoalewa, discovered in 2016, is an asteroid only about 45–58 meters across. It orbits the Sun, but its path keeps it close to Earth. That makes it a quasi-satellite.
It's extremely hard to study. It can only be observed for a few weeks each April, and it's about 4 million times fainter than the faintest star you can see with the naked eye.
Using the Large Binocular Telescope, astronomers measured the light it reflects and found a surprise. Its spectrum matched lunar rocks brought back by the Apollo missions, not typical near-Earth asteroids.
That suggests it might be a fragment blasted off the Moon by an ancient impact. The team was careful, though: no other known asteroid has a lunar origin, and it's not clear how this piece escaped.
Its current orbit is temporary too. Calculations suggest it settled into this path around 500 years ago and will leave in roughly 300 more.
The Moon may have a lost fragment that still travels alongside us, just out of sight.
9. 🕳️ MoM-BH*-1 may be a black hole disguised as a star
Webb's earliest images held a surprise: compact, strikingly red specks in the young universe, nicknamed little red dots in 2023. At first they were taken for galaxies, then for supermassive black holes, but neither label fit comfortably.
In August 2026, a study in Nature described one called MoM-BH*-1, seen a few hundred million years after the Big Bang. Its light drops off more sharply below a certain wavelength than in any object ever observed, and it shows almost nothing but hydrogen and helium.
The team's best explanation is a black hole star: a black hole of about 100,000 solar masses buried inside a dense cocoon of hydrogen roughly the size of our Solar System. The cocoon glows like the surface of a star, but the energy comes from gas falling into the black hole, not from fusion.
Not everyone agrees. Other astronomers argue that little red dots are more ordinary black holes wrapped in gas and dust, whose color depends on the angle we see them from.
If the idea holds, some of the universe's first giant black holes may have started life hidden inside something that looked like a star.
10. 🪐 Saturn hides an enormous ring we can't see
Saturn's famous rings are bright and thin. In 2009, NASA's Spitzer Space Telescope found another one that is neither.
Spitzer detected the faint infrared glow of cold dust in a ring that begins about 6 million kilometers from Saturn and extends roughly 12 million kilometers farther out. It's about 20 times as thick as Saturn is wide, and it would take about a billion Earths to fill it.
The ring is tilted 27 degrees from the main rings, and Saturn's distant moon Phoebe orbits within it. Scientists think Phoebe is the ring's source.
The particles are so spread out that you could stand inside the ring without noticing. Yet they may solve an old puzzle. The ring circles Saturn in the opposite direction to the moon Iapetus, and dust drifting inward may hit Iapetus "like bugs on a windshield," darkening one side of it.
Saturn's largest ring is so faint it's invisible to the eye, yet so large it dwarfs the planet itself.
11. 🟤 W1935 has a glow that shouldn't be there
Brown dwarfs sit between planets and stars: too massive to be planets, too small to shine by fusion like the Sun. W1935, about 47 light-years away, is a cold, lonely one, with no star nearby.
When Webb studied it, astronomers expected methane in its atmosphere to absorb infrared light. Instead, the methane was glowing. A near-twin brown dwarf, W2220, showed the normal absorption.
Models suggest W1935's upper atmosphere gets warmer with height. On Jupiter and Saturn, similar heating is linked to aurorae, the same kind of glowing light show we see near Earth's poles. So W1935 became the first auroral candidate outside the Solar System with a methane glow.
But there's a problem. The aurorae on Jupiter and Saturn are fed partly by the solar wind, and W1935 has no star to supply one. The energy might come from processes inside the brown dwarf, from interstellar plasma, or perhaps from an active moon we haven't found.
It may be a sky lit with aurorae, with no sun anywhere nearby.
12. 🌙 A planet-sized object may orbit a brown dwarf like a moon
What do you call something as heavy as Jupiter that orbits an object which orbits a star?
The star CD-35 2722 has about half the Sun's mass. Around it orbits a brown dwarf more than 30 times as massive as Jupiter. Using the CRIRES+ instrument on the Very Large Telescope, astronomers watched that brown dwarf wobble back and forth and found the signature of something circling it: an object at least as massive as Jupiter.
The study, published in Nature in July 2026, calls it an exosatellite. If confirmed, it could be the first "moon" found outside our Solar System. As one of the researchers put it, "being the third wheel in this system makes us want to call it a moon."
It's still a candidate, not a confirmed detection, and there's no official definition of an exomoon. Is a Jupiter-mass body around a brown dwarf a moon, or a planet, or something new?
Nature doesn't sort itself into our categories. Sometimes it hands us an object that blurs the lines between stars, planets and moons.
13. ☄️ Sedna's orbit points to a crowded childhood for the Sun
In November 2003, astronomers found a small, reddish world about 13 billion kilometers from the Sun. They named it Sedna.
Its distance wasn't the strangest part. Sedna follows a long, stretched orbit that carries it out to roughly 130 billion kilometers, about 900 times Earth's distance from the Sun, and takes about 10,500 years to complete. Out there, temperatures never rise above minus 240 °C. After Mars, it's the second-reddest object known in the Solar System.
Its orbit resembles those predicted for the Oort cloud, the vast reservoir of icy bodies that supplies long-period comets. But Sedna sits about ten times closer than the cloud's predicted inner edge, and its stretched orbit was unlike anything astronomers had seen before.
One idea from its discoverers is that a star passed close to the young Sun and tugged Sedna onto its path. If so, Sedna's orbit may preserve the gravitational fingerprint of a long-gone neighbor.
A single faraway orbit may remember a visit from another star billions of years ago.
14. 🌌 The faint radio whisper of cosmic dawn is still disputed
Before the first stars switched on, the universe was filled with hydrogen gas. Hydrogen atoms can absorb or emit radio waves with a wavelength of 21 centimeters, and the first stars changed how that gas behaved.
So somewhere in the radio sky there should be a faint signature of cosmic dawn, the moment the universe first lit up.
In 2018, the EDGES experiment reported a possible detection. But the signal was unusually strong compared with the simplest models, and it needed independent confirmation.
In 2022, a team using SARAS 3, a radio telescope in India, looked for the same signal and didn't find it. Even a non-detection was useful. It ruled out some scenarios for the first galaxies, such as ones that were more than a thousand times brighter in radio than today's galaxies while also doing a poor job of heating the gas around them.
The question isn't settled. New experiments and, later, the Square Kilometre Array should help.
The first light in the universe left a mark in radio waves, and we're still trying to hear it clearly.
15. 🌌 The Milky Way and Andromeda may not collide after all
For years, the story seemed fixed: in about 4.5 billion years, the Milky Way and the Andromeda galaxy would crash together and merge.
In 2025, a team led by Till Sawala revisited that forecast using data from Hubble and Gaia. They considered 22 uncertain quantities and ran 100,000 simulations of the next 10 billion years.
Their result was humbling. The chance of a merger within 10 billion years is only about 50%. A head-on collision within the next 4 to 5 billion years happens in only about 2% of the simulations.
Smaller galaxies matter. Andromeda's companion, the Triangulum galaxy, pulls the two big galaxies toward each other. The Large Magellanic Cloud pulls the Milky Way off course, making a collision less likely. In some simulated futures, the galaxies swing past each other at about 500,000 light-years, then fall back and merge much later.
None of this changes what happens closer to home. The brightening Sun will make Earth uninhabitable in about a billion years, long before either galaxy arrives.
The future of our galaxy is not a fixed date on a calendar, but a spread of possibilities.
🌙 One last thought before you sleep
So much of tonight happened on a human timescale.
A dying star got six times hotter in the time it takes a child to grow up. Two collisions lit up the dust around Fomalhaut within twenty years. A small asteroid settled near Earth about five centuries ago, before anyone had a telescope to look for it, and it will be gone again in a few hundred years.
We often think of the universe as slow and settled, a painting that changes too slowly for us to see. It isn't. It's moving all the time, and sometimes it moves fast enough for us to catch.
Even the biggest future, the meeting of two galaxies, turns out to be open. Nobody has written it yet.
We happen to be awake during one short scene of a very long story, and we can still watch it change.
That's all for tonight. Thanks for wondering along with me. Good night, and clear skies. 🌌
— Kasi