As the sun sets over the stark Martian landscape, stars come into view. Is there a North Star for Mars? Image via Spirit Mars rover on May 19, 2005/ NASA.
The North Star for Earth is Polaris. Does our next-door neighbor planet, Mars, have the same North Star as Earth? If not, does Mars have a star located more or less above its north pole?
Let’s talk about what we mean by North Star. Every planet in our solar system spins on its axis. Earth’s spin is what defines the length of our day of approximately 24 hours. If you continue the imaginary line of a planet’s axis out into space, it might point to a star that’s visible to the eye.
We call such stars pole stars. On Earth, the northern pole star — less than a degree from the north celestial pole — is the beloved star Polaris. Scouts and hikers know you can use Polaris to find the direction north when compasses or GPS fails.
However, Earth’s Southern Hemisphere doesn’t have a comparable South Star. The nearest visible star to the south celestial pole of Earth is about 9 degrees away.
Artist’s illustration of the relative tilts of the orbits of Earth and Mars, Earth doesn’t orbit exactly upright with respect to our orbit around the sun. Instead, Earth’s tilt is about 23 1/2 degrees. Meanwhile, Mars’ tilt is about 25 degrees. What’s more, the orbits of Earth and Mars aren’t tilted in the same direction, as in this illustration. For both reasons — different amount of tilt and different direction of tilt — Mars doesn’t have the same North Star as Earth. Image via NASA.
A North Star for Mars?
So, does Mars have a North or South Star? The answer is … not in any satisfying way. There’s no bright North Star, and only a modestly-bright South Star, for Mars.
In the northern sky as seen from Mars, the best candidate for a North Star is located on Mars’ sky dome about 1/2 degree from Mars’ north celestial pole. That’s closer than Polaris is to Earth’s north celestial pole. So what’s the problem? Well, while Polaris is relatively bright (47th brightest of all stars in the night sky), the star near Mars’ north celestial pole is faint.
In fact, this star is barely within the limit of visibility to the eye alone. That makes it a poor candidate for a North Star.
Mars’ north pole points to a spot in the sky that’s about midway between Deneb, the brightest star in the constellation Cygnus the Swan, and Alderamin, the brightest star in the constellation Cepheus the King. See a chart of the position of Mars’ north celestial pole between the constellations Cygnus and Cepheus.
The southern sky view from Mars
Meanwhile, in the southern sky as seen from Mars, Kappa Velorum is only about 3 degrees from the Martian south celestial pole. That’s not as close as Polaris is to Earth’s north celestial pole, plus this star is only modestly bright, not nearly as bright as Polaris.
Future Mars colonists aren’t going to have a bright North Star — like our Polaris — to guide them.
On the other hand, if you were standing outside at night on the surface of Mars, you’d see some other cool stuff!
Earth and moon, as seen from Mars by the Curiosity rover in 2014. From Mars, you’d see both the Earth and moon with the eye alone. Image via NASA.
Can you see the moon orbiting Earth from Mars?
As seen from Mars, you could see Earth’s moon orbiting around Earth. From Earth, we can’t see any other planets’ satellites with the unaided eye, but this amazing sight on Mars would be visible to the eye alone. Both the Earth and the moon would appear starlike.
In general, the Earth as seen from Mars would somewhat mimic our view of Venus as seen from Earth. By that we mean that — like Venus in relationship to Earth — Earth in relationship to Mars is an inner planet. It orbits closer to the sun than Mars. Thus, Earth as seen from Mars would constantly shift from a morning to an evening “star” and back, just as Venus does as seen from our world.
And although both Earth and the moon would appear as stars to the unaided eye, observers on Mars with telescopes would sometimes see them as crescent worlds, just as we see Venus.
So … no North Star for Mars. But Martian stargazers wouldn’t lack for things to see!
This series of images shows the Martian moon Phobos as it crossed in front of the sun, as seen by NASA’s Curiosity Mars rover on Tuesday, March 26, 2019 (Sol 2359). Image via NASA/ JPL-Caltech.
Bottom line: Does planet Mars have a North Star akin to Earth’s North Star Polaris? No, there is not a Mars North Star. But Martian stargazers wouldn’t lack for things to see!
As the sun sets over the stark Martian landscape, stars come into view. Is there a North Star for Mars? Image via Spirit Mars rover on May 19, 2005/ NASA.
The North Star for Earth is Polaris. Does our next-door neighbor planet, Mars, have the same North Star as Earth? If not, does Mars have a star located more or less above its north pole?
Let’s talk about what we mean by North Star. Every planet in our solar system spins on its axis. Earth’s spin is what defines the length of our day of approximately 24 hours. If you continue the imaginary line of a planet’s axis out into space, it might point to a star that’s visible to the eye.
We call such stars pole stars. On Earth, the northern pole star — less than a degree from the north celestial pole — is the beloved star Polaris. Scouts and hikers know you can use Polaris to find the direction north when compasses or GPS fails.
However, Earth’s Southern Hemisphere doesn’t have a comparable South Star. The nearest visible star to the south celestial pole of Earth is about 9 degrees away.
Artist’s illustration of the relative tilts of the orbits of Earth and Mars, Earth doesn’t orbit exactly upright with respect to our orbit around the sun. Instead, Earth’s tilt is about 23 1/2 degrees. Meanwhile, Mars’ tilt is about 25 degrees. What’s more, the orbits of Earth and Mars aren’t tilted in the same direction, as in this illustration. For both reasons — different amount of tilt and different direction of tilt — Mars doesn’t have the same North Star as Earth. Image via NASA.
A North Star for Mars?
So, does Mars have a North or South Star? The answer is … not in any satisfying way. There’s no bright North Star, and only a modestly-bright South Star, for Mars.
In the northern sky as seen from Mars, the best candidate for a North Star is located on Mars’ sky dome about 1/2 degree from Mars’ north celestial pole. That’s closer than Polaris is to Earth’s north celestial pole. So what’s the problem? Well, while Polaris is relatively bright (47th brightest of all stars in the night sky), the star near Mars’ north celestial pole is faint.
In fact, this star is barely within the limit of visibility to the eye alone. That makes it a poor candidate for a North Star.
Mars’ north pole points to a spot in the sky that’s about midway between Deneb, the brightest star in the constellation Cygnus the Swan, and Alderamin, the brightest star in the constellation Cepheus the King. See a chart of the position of Mars’ north celestial pole between the constellations Cygnus and Cepheus.
The southern sky view from Mars
Meanwhile, in the southern sky as seen from Mars, Kappa Velorum is only about 3 degrees from the Martian south celestial pole. That’s not as close as Polaris is to Earth’s north celestial pole, plus this star is only modestly bright, not nearly as bright as Polaris.
Future Mars colonists aren’t going to have a bright North Star — like our Polaris — to guide them.
On the other hand, if you were standing outside at night on the surface of Mars, you’d see some other cool stuff!
Earth and moon, as seen from Mars by the Curiosity rover in 2014. From Mars, you’d see both the Earth and moon with the eye alone. Image via NASA.
Can you see the moon orbiting Earth from Mars?
As seen from Mars, you could see Earth’s moon orbiting around Earth. From Earth, we can’t see any other planets’ satellites with the unaided eye, but this amazing sight on Mars would be visible to the eye alone. Both the Earth and the moon would appear starlike.
In general, the Earth as seen from Mars would somewhat mimic our view of Venus as seen from Earth. By that we mean that — like Venus in relationship to Earth — Earth in relationship to Mars is an inner planet. It orbits closer to the sun than Mars. Thus, Earth as seen from Mars would constantly shift from a morning to an evening “star” and back, just as Venus does as seen from our world.
And although both Earth and the moon would appear as stars to the unaided eye, observers on Mars with telescopes would sometimes see them as crescent worlds, just as we see Venus.
So … no North Star for Mars. But Martian stargazers wouldn’t lack for things to see!
This series of images shows the Martian moon Phobos as it crossed in front of the sun, as seen by NASA’s Curiosity Mars rover on Tuesday, March 26, 2019 (Sol 2359). Image via NASA/ JPL-Caltech.
Bottom line: Does planet Mars have a North Star akin to Earth’s North Star Polaris? No, there is not a Mars North Star. But Martian stargazers wouldn’t lack for things to see!
Taurid meteors consist of 2 streams, the South Taurids and North Taurids. Both streams radiate from the constellation Taurus the Bull, not far from the bright star Aldebaran and the tiny, misty, dipper-shaped Pleiades. Taurus is high in the sky in the middle of the night now. So the hours around midnight are a good time to watch for Taurid meteors and fireballs, as they appear to originate from the constellation Taurus. In October and November, this constellation is highest in the sky in the middle of the night.
You might see South Taurid meteors any time from about September 10 to November 20. The North Taurids stem from a nearby but slightly different stream. They’re active from about October 20 to December 10. Both showers produce about five meteors per hour (10 total when they overlap) and some of them are fireballs.
Predicted peak: According the the RASC Observer’s Guide, the South Taurids’ predicted peak is for 19 UTC on November 5, 2026. The North Taurids’ predicted peak is for 18 UTC on November 12, 2026. Both the South and North Taurids don’t have very definite peaks. They ramble along in October and November and are especially noticeable from late October into early November, when they overlap. When to watch: Best around midnight when the radiant is highest in the sky. Overall duration of shower: The South Taurids run from about September 23 to November 12. This time period is when we’re passing through the Southern Taurid meteor stream in space. North Taurids are active from about October 13 to December 2. And this time period is when we’re passing through the Northern Taurid meteor stream in space. Radiant: Rises in early evening, highest in the sky around midnight. See chart below. Nearest moon phases: In 2026, the new moon falls at 7:02 UTC on November 9. So moonlight will not interfere with Taurid meteors in 2026. You’ll catch Taurid meteors throughout October and November. Visit Sunrise Sunset Calendars to see moon rising times for your location. Be sure to check the moon rising time box. Expected meteors at peak, under ideal conditions: Under dark skies with no moon, both the South and North Taurid meteor showers produce about five meteors per hour (10 total when they overlap). Also, watch for fireballs. In most years, only 1% of all Taurid meteors are fireballs. In exceptional years, when the Earth passes through a concentrated field of debris, the percentage can be as high as 7%. Note: Taurid meteors tend to be slow-moving but sometimes very bright. The showers sometimes produce fireballs, which made their cyclical reappearance in 2008, 2015 and 2022. The next predicted swarm or outburst of Taurid fireballs is in 2032.
The object responsible for the Northern Taurid meteor shower is believed to be an asteroid. And that asteroid is related to a comet.
The asteroid is named 2004 TG10. The Spacewatch program discovered it on October 8, 2004. Its orbit around the sun closely matches that of periodic Comet Encke (officially known as 2P/Encke). Scientists believe this asteroid was once part of a much larger object known as the Encke Complex.
The most widely accepted theory is that about 20,000 years ago, a much larger object broke up, creating Comet Encke and several asteroids and meteor showers. Scientists named this group of resultant objects after the most prominent member of the group: Comet Encke. Hence, the Encke Complex.
No single asteroid produces Taurid meteors
A recent study indicates that the asteroid 2004 TG10 is only one of 10 related asteroids that may be responsible for this meteor shower. If that is true, then no single asteroid is producing the material causing the Northern Taurid meteors.
How is a mystery like this solved? Time and teamwork. Special nighttime video cameras record incoming meteors, and computers calculate the orbit almost immediately. Scientists compare these orbits to known objects, such as comets and asteroids. A direct match is unlikely, because any piece of material ejected from a comet or asteroid — perhaps hundreds of years ago — has been subjected to solar radiation and planetary perturbations that change its path around the sun. So, its final orbit, just before it enters our atmosphere, is likely different than the orbit it originated from. Astronomers who specialize in celestial mechanics will be the ones to bring us the solution.
Cameras and computers are likely to give us a better picture and a more thorough understanding of the Northern Taurids meteor shower.
The material we see as meteors from the Southern Taurids radiant comes from the comet known as Encke’s Comet. Officially known as 2P/Encke, this comet was discovered four times before it received its name.
The French comet hunter Pierre Mechian discovered it on January 17, 1786. He observed the comet for only three days and did not calculate its orbit. Next up was Caroline Herschel of England, who found it on November 7, 1795, 10 years later. She tracked it for 23 days but did not calculate an accurate orbit. Ten years later, Frenchman Jean-Louis Pons, the greatest visual comet hunter of all time, picked it up on October 20, 1805. Within hours of Pons’ discovery, Hofrath Huth of Germany and Alexis Bouvard in Paris picked it up too. This time they followed it for 32 days.
Enter Johann Franz Encke. Using these positions, he calculated an orbit for this comet and predicted that it would return. End of story? No, because he predicted it would return in 12.12 years. And it didn’t.
Tracking a new comet
Then, on November 26, 1818, Pons picked up a comet and tracked it for 48 days. Encke calculated an orbit for this one, and using some new computing techniques, came up with an orbital solution suggesting the comet takes only 3.3 years to go around the sun once. After six weeks of work, he was also able to link this comet to the comets of 1786, 1795 and 1805. He then correctly predicted that it would return in 1822. Based upon his work correctly calculating the comet’s orbit, the comet received the name Encke.
Comet Encke has the shortest orbital period of any major comet in our solar system. At its closest, it gets as close to the sun as does the planet Mercury, the planet closest to the sun. The orbit is stable, and the comet has probably been in the same orbit for thousands of years.
Was Comet Encke once part of a larger comet?
A recent theory is that Comet Encke was once part of a larger comet that broke up about 20,000 years ago. This event produced several small asteroids and the debris that now forms this meteor shower. And there are more. Scientists attribute at least three other meteor showers to Comet Encke. One stream of material might have delivered the object responsible for the Tunguska meteor event of 1908. This whole system is known as the Encke Complex.
Comet Encke, parent of the Taurid meteor showers. Image via NASA.
The next return of Comet Encke will be in July 2030.
What about Taurid fireballs?
Astronomers studying the Taurids found that Earth encounters a concentration of larger-than-normal debris at intervals of three or seven years resulting in a higher rate of fireballs.
Taurid fireballs — visible in Earth’s skies in October and November — are often colorful. They often fragment as they streak slowly through the sky. In most years, only 1% of all Taurid meteors are fireballs. In exceptional years, when the Earth passes through a concentrated field of debris, the percentage can be as high as 7%. So visual observers and astrophotographers might see several fireballs each night instead of the normal rate of one every 20 hours.
And they were right! There were lots of fireball sightings in 2022.
The next predicted Taurid swarm is in 2032 and appears to be an exceptional year, as the moon will be new and Earth will pass very close to the center of the swarm.
The story of the predicted peaks for the Taurids — which vary from place to place across the internet — is interesting. And a big reason is that astronomers are always learning new things.
For the most part, we count on the American Meteor Society and the Observer’s Handbook from the Royal Astronomical Society of Canada to provide us with the peak dates for the year’s major meteor showers.
So predicted peaks will vary. It’s nature! We don’t have it entirely pinned down.
View at EarthSky Community Photos. | Joel Weatherly in Edmonton, Alberta, Canada, created this composite from images captured on the morning of November 11, 2020. He wrote, “This is a composite image featuring Taurus and 4 meteors that I observed while out for the Northern Taurids meteor shower. The 2 brightest meteors left behind dust trails.” Thank you, Joel!
Bottom line: You might see a South Taurid meteor any time from about September 10 to November 20. That’s when Earth is plowing through the meteor stream – the stream of comet debris in space – that creates this meteor shower. The North Taurids stem from a nearby, but slightly different stream. They’re active from about October 20 to December 10. Both showers produce about five meteors per hour (10 total when they overlap).
**Predicted peak times and dates for meteor showers are from the American Meteor Society. Note that meteor shower peak times can vary.
Taurid meteors consist of 2 streams, the South Taurids and North Taurids. Both streams radiate from the constellation Taurus the Bull, not far from the bright star Aldebaran and the tiny, misty, dipper-shaped Pleiades. Taurus is high in the sky in the middle of the night now. So the hours around midnight are a good time to watch for Taurid meteors and fireballs, as they appear to originate from the constellation Taurus. In October and November, this constellation is highest in the sky in the middle of the night.
You might see South Taurid meteors any time from about September 10 to November 20. The North Taurids stem from a nearby but slightly different stream. They’re active from about October 20 to December 10. Both showers produce about five meteors per hour (10 total when they overlap) and some of them are fireballs.
Predicted peak: According the the RASC Observer’s Guide, the South Taurids’ predicted peak is for 19 UTC on November 5, 2026. The North Taurids’ predicted peak is for 18 UTC on November 12, 2026. Both the South and North Taurids don’t have very definite peaks. They ramble along in October and November and are especially noticeable from late October into early November, when they overlap. When to watch: Best around midnight when the radiant is highest in the sky. Overall duration of shower: The South Taurids run from about September 23 to November 12. This time period is when we’re passing through the Southern Taurid meteor stream in space. North Taurids are active from about October 13 to December 2. And this time period is when we’re passing through the Northern Taurid meteor stream in space. Radiant: Rises in early evening, highest in the sky around midnight. See chart below. Nearest moon phases: In 2026, the new moon falls at 7:02 UTC on November 9. So moonlight will not interfere with Taurid meteors in 2026. You’ll catch Taurid meteors throughout October and November. Visit Sunrise Sunset Calendars to see moon rising times for your location. Be sure to check the moon rising time box. Expected meteors at peak, under ideal conditions: Under dark skies with no moon, both the South and North Taurid meteor showers produce about five meteors per hour (10 total when they overlap). Also, watch for fireballs. In most years, only 1% of all Taurid meteors are fireballs. In exceptional years, when the Earth passes through a concentrated field of debris, the percentage can be as high as 7%. Note: Taurid meteors tend to be slow-moving but sometimes very bright. The showers sometimes produce fireballs, which made their cyclical reappearance in 2008, 2015 and 2022. The next predicted swarm or outburst of Taurid fireballs is in 2032.
The object responsible for the Northern Taurid meteor shower is believed to be an asteroid. And that asteroid is related to a comet.
The asteroid is named 2004 TG10. The Spacewatch program discovered it on October 8, 2004. Its orbit around the sun closely matches that of periodic Comet Encke (officially known as 2P/Encke). Scientists believe this asteroid was once part of a much larger object known as the Encke Complex.
The most widely accepted theory is that about 20,000 years ago, a much larger object broke up, creating Comet Encke and several asteroids and meteor showers. Scientists named this group of resultant objects after the most prominent member of the group: Comet Encke. Hence, the Encke Complex.
No single asteroid produces Taurid meteors
A recent study indicates that the asteroid 2004 TG10 is only one of 10 related asteroids that may be responsible for this meteor shower. If that is true, then no single asteroid is producing the material causing the Northern Taurid meteors.
How is a mystery like this solved? Time and teamwork. Special nighttime video cameras record incoming meteors, and computers calculate the orbit almost immediately. Scientists compare these orbits to known objects, such as comets and asteroids. A direct match is unlikely, because any piece of material ejected from a comet or asteroid — perhaps hundreds of years ago — has been subjected to solar radiation and planetary perturbations that change its path around the sun. So, its final orbit, just before it enters our atmosphere, is likely different than the orbit it originated from. Astronomers who specialize in celestial mechanics will be the ones to bring us the solution.
Cameras and computers are likely to give us a better picture and a more thorough understanding of the Northern Taurids meteor shower.
The material we see as meteors from the Southern Taurids radiant comes from the comet known as Encke’s Comet. Officially known as 2P/Encke, this comet was discovered four times before it received its name.
The French comet hunter Pierre Mechian discovered it on January 17, 1786. He observed the comet for only three days and did not calculate its orbit. Next up was Caroline Herschel of England, who found it on November 7, 1795, 10 years later. She tracked it for 23 days but did not calculate an accurate orbit. Ten years later, Frenchman Jean-Louis Pons, the greatest visual comet hunter of all time, picked it up on October 20, 1805. Within hours of Pons’ discovery, Hofrath Huth of Germany and Alexis Bouvard in Paris picked it up too. This time they followed it for 32 days.
Enter Johann Franz Encke. Using these positions, he calculated an orbit for this comet and predicted that it would return. End of story? No, because he predicted it would return in 12.12 years. And it didn’t.
Tracking a new comet
Then, on November 26, 1818, Pons picked up a comet and tracked it for 48 days. Encke calculated an orbit for this one, and using some new computing techniques, came up with an orbital solution suggesting the comet takes only 3.3 years to go around the sun once. After six weeks of work, he was also able to link this comet to the comets of 1786, 1795 and 1805. He then correctly predicted that it would return in 1822. Based upon his work correctly calculating the comet’s orbit, the comet received the name Encke.
Comet Encke has the shortest orbital period of any major comet in our solar system. At its closest, it gets as close to the sun as does the planet Mercury, the planet closest to the sun. The orbit is stable, and the comet has probably been in the same orbit for thousands of years.
Was Comet Encke once part of a larger comet?
A recent theory is that Comet Encke was once part of a larger comet that broke up about 20,000 years ago. This event produced several small asteroids and the debris that now forms this meteor shower. And there are more. Scientists attribute at least three other meteor showers to Comet Encke. One stream of material might have delivered the object responsible for the Tunguska meteor event of 1908. This whole system is known as the Encke Complex.
Comet Encke, parent of the Taurid meteor showers. Image via NASA.
The next return of Comet Encke will be in July 2030.
What about Taurid fireballs?
Astronomers studying the Taurids found that Earth encounters a concentration of larger-than-normal debris at intervals of three or seven years resulting in a higher rate of fireballs.
Taurid fireballs — visible in Earth’s skies in October and November — are often colorful. They often fragment as they streak slowly through the sky. In most years, only 1% of all Taurid meteors are fireballs. In exceptional years, when the Earth passes through a concentrated field of debris, the percentage can be as high as 7%. So visual observers and astrophotographers might see several fireballs each night instead of the normal rate of one every 20 hours.
And they were right! There were lots of fireball sightings in 2022.
The next predicted Taurid swarm is in 2032 and appears to be an exceptional year, as the moon will be new and Earth will pass very close to the center of the swarm.
The story of the predicted peaks for the Taurids — which vary from place to place across the internet — is interesting. And a big reason is that astronomers are always learning new things.
For the most part, we count on the American Meteor Society and the Observer’s Handbook from the Royal Astronomical Society of Canada to provide us with the peak dates for the year’s major meteor showers.
So predicted peaks will vary. It’s nature! We don’t have it entirely pinned down.
View at EarthSky Community Photos. | Joel Weatherly in Edmonton, Alberta, Canada, created this composite from images captured on the morning of November 11, 2020. He wrote, “This is a composite image featuring Taurus and 4 meteors that I observed while out for the Northern Taurids meteor shower. The 2 brightest meteors left behind dust trails.” Thank you, Joel!
Bottom line: You might see a South Taurid meteor any time from about September 10 to November 20. That’s when Earth is plowing through the meteor stream – the stream of comet debris in space – that creates this meteor shower. The North Taurids stem from a nearby, but slightly different stream. They’re active from about October 20 to December 10. Both showers produce about five meteors per hour (10 total when they overlap).
**Predicted peak times and dates for meteor showers are from the American Meteor Society. Note that meteor shower peak times can vary.
These 3 images show asteroid 6993 (1995 BJ4) on 3 separate dates this summer. Is this active asteroid better described as a comet, or did it grow a tail due to a collision? Image via the Zwicky Transient Facility/ NAU/ arXiv.
This active asteroid has grown a tail!
This summer, astronomers spotted something unusual about an asteroid in the main asteroid belt between Mars and Jupiter. The asteroid, named 6993 or 1995 BJ4, appeared to be shedding material and growing a tail, much like a comet. So how should we describe this strange object?
Astronomers are calling it an active asteroid … but it might become known as a comet. More specifically, it could join the small family of main-belt comets, or objects in the main asteroid belt with cometlike features.
However, that’s not the only explanation for this activity. The tail that’s showing up in these images could be the result of a collision among bodies in the main asteroid belt.
If the object does prove to be cometary in nature — with a tail created by sunlight vaporizing ice on its surface — 1995 BJ4 would be the largest-known main-belt comet. It’s about 7.5 miles (12 km) across. That makes it larger than 99% of asteroids. 1995 BJ4 also travels farther from the sun than most known active asteroids do.
Researchers with Northern Arizona University and other institutions discovered the activity using observations from the Zwicky Transient Facility. They published their study on October 22, 2026, on arXiv. It is not yet peer-reviewed.
Most asteroids are static, rocky objects. The majority live in the main asteroid belt between Mars and Jupiter.
But some asteroids occasionally become active. They release dust and gas, creating a fuzzy cloud around the object or a visible tail. Astronomers call these objects active asteroids. And some are considered main-belt comets because they behave like comets while traveling among the asteroids. So far, astronomers have only found about 20 main-belt comets.
The discovery of 1995 BJ4 came through an automated system called the Solar System Notification Alert Processing System. Researchers trained a machine-learning model to recognize the fuzzy appearance of active asteroids. And on August 5, the model flagged an image of 1995 BJ4 with 99.9% confidence.
The team then checked earlier observations and found the tail had already been visible in images from the Zwicky Transient Facility dating back to June 25, 2026. The object showed a narrow, straight tail extending at least 32 arcseconds beyond its main body.
What is making the asteroid active?
The researchers considered several explanations for the activity.
One possibility that didn’t stand up to testing was the idea that the asteroid’s rotation is throwing material into space. But asteroid 1995 BJ4 rotates once every 3.9 hours. That’s not fast enough to achieve what the observations show.
But two other possibilities are still in the running.
One is that an impact with another space rock blasted dust from the asteroid’s surface. If so, the dust could gradually spread into space, causing the tail to fade over time. Because the asteroid appeared a tiny bit brighter in June and July than it was in August and September, that could point toward a collision with dust slowly dispersing.
But the possibility of sublimation — or sunlight warming buried ice — has not been ruled out. Sublimation is what causes material to vaporize on comets, carrying that material away from the surface. This process creates the familiar comas and tails of comets.
So both collision and sublimation are still possibilities, and the active asteroid’s true nature remains a secret, for now.
A possible record-setting main-belt comet
If it turns out that the tail is due to sublimation, it would make 1995 BJ4 the largest-known main-belt comet. Plus, it orbits farther from the sun than any known main-belt comet. Its closest approach to the sun, or perihelion, is about 2.85 times Earth’s distance from our star.
The active asteroid 6993 (1995 BJ4) orbits between Mars and Jupiter, in the outer edge of the main asteroid belt. Image via Tony Dunn.
Watch this asteroid in 2027
The researchers said continued observations will be important for figuring out what’s driving the activity.
1995 BJ4 will reach perihelion in January 2027. So if sunlight is vaporizing ice, astronomers might see its activity increase. But if the tail continues to fade, that would lend support to the impact explanation.
Scientists also hope to learn more about the asteroid’s composition. Its colors and reflectivity don’t fit neatly into existing classifications, leaving some uncertainty about what its surface contains.
Bottom line: Active asteroid 1995 BJ4 has grown a cometlike tail, leaving astronomers wondering what’s happening.
These 3 images show asteroid 6993 (1995 BJ4) on 3 separate dates this summer. Is this active asteroid better described as a comet, or did it grow a tail due to a collision? Image via the Zwicky Transient Facility/ NAU/ arXiv.
This active asteroid has grown a tail!
This summer, astronomers spotted something unusual about an asteroid in the main asteroid belt between Mars and Jupiter. The asteroid, named 6993 or 1995 BJ4, appeared to be shedding material and growing a tail, much like a comet. So how should we describe this strange object?
Astronomers are calling it an active asteroid … but it might become known as a comet. More specifically, it could join the small family of main-belt comets, or objects in the main asteroid belt with cometlike features.
However, that’s not the only explanation for this activity. The tail that’s showing up in these images could be the result of a collision among bodies in the main asteroid belt.
If the object does prove to be cometary in nature — with a tail created by sunlight vaporizing ice on its surface — 1995 BJ4 would be the largest-known main-belt comet. It’s about 7.5 miles (12 km) across. That makes it larger than 99% of asteroids. 1995 BJ4 also travels farther from the sun than most known active asteroids do.
Researchers with Northern Arizona University and other institutions discovered the activity using observations from the Zwicky Transient Facility. They published their study on October 22, 2026, on arXiv. It is not yet peer-reviewed.
Most asteroids are static, rocky objects. The majority live in the main asteroid belt between Mars and Jupiter.
But some asteroids occasionally become active. They release dust and gas, creating a fuzzy cloud around the object or a visible tail. Astronomers call these objects active asteroids. And some are considered main-belt comets because they behave like comets while traveling among the asteroids. So far, astronomers have only found about 20 main-belt comets.
The discovery of 1995 BJ4 came through an automated system called the Solar System Notification Alert Processing System. Researchers trained a machine-learning model to recognize the fuzzy appearance of active asteroids. And on August 5, the model flagged an image of 1995 BJ4 with 99.9% confidence.
The team then checked earlier observations and found the tail had already been visible in images from the Zwicky Transient Facility dating back to June 25, 2026. The object showed a narrow, straight tail extending at least 32 arcseconds beyond its main body.
What is making the asteroid active?
The researchers considered several explanations for the activity.
One possibility that didn’t stand up to testing was the idea that the asteroid’s rotation is throwing material into space. But asteroid 1995 BJ4 rotates once every 3.9 hours. That’s not fast enough to achieve what the observations show.
But two other possibilities are still in the running.
One is that an impact with another space rock blasted dust from the asteroid’s surface. If so, the dust could gradually spread into space, causing the tail to fade over time. Because the asteroid appeared a tiny bit brighter in June and July than it was in August and September, that could point toward a collision with dust slowly dispersing.
But the possibility of sublimation — or sunlight warming buried ice — has not been ruled out. Sublimation is what causes material to vaporize on comets, carrying that material away from the surface. This process creates the familiar comas and tails of comets.
So both collision and sublimation are still possibilities, and the active asteroid’s true nature remains a secret, for now.
A possible record-setting main-belt comet
If it turns out that the tail is due to sublimation, it would make 1995 BJ4 the largest-known main-belt comet. Plus, it orbits farther from the sun than any known main-belt comet. Its closest approach to the sun, or perihelion, is about 2.85 times Earth’s distance from our star.
The active asteroid 6993 (1995 BJ4) orbits between Mars and Jupiter, in the outer edge of the main asteroid belt. Image via Tony Dunn.
Watch this asteroid in 2027
The researchers said continued observations will be important for figuring out what’s driving the activity.
1995 BJ4 will reach perihelion in January 2027. So if sunlight is vaporizing ice, astronomers might see its activity increase. But if the tail continues to fade, that would lend support to the impact explanation.
Scientists also hope to learn more about the asteroid’s composition. Its colors and reflectivity don’t fit neatly into existing classifications, leaving some uncertainty about what its surface contains.
Bottom line: Active asteroid 1995 BJ4 has grown a cometlike tail, leaving astronomers wondering what’s happening.
This Hubble Space Telescope image shows a cloud in space where new stars are forming called 30 Doradus, aka the Tarantula Nebula. The enlarged inset shows a star that appears to have been kicked out of the nebula. In the inset, an arrow points to the runaway star and a dashed arrow to its presumed direction of motion. Image via NASA.
A runaway star moves faster and in a different direction
The sun and all of the Milky Way’s stars are moving in orbit around the center of our galaxy. It’s more or less orderly … but astronomers have identified some Milky Way stars that are moving faster than expected, and often in a direction that seems unusual. They use the term runaway star to describe these renegades.
Stars form in clouds of gas and dust. Multiple stars form from a single cloud. Therefore, many Milky Way stars move through space in loose associations, or more tightly bound open star clusters. By tracking the motions of a runaway star, astronomers can sometimes determine its original stellar companion. And, sometimes, they can work out what must have happened to kick the star on a different and much faster path to these stars.
Astronomers point to 2 possible reasons for a runaway star
The first scenario involves two binary star systems — two systems, each containing two stars — that pass close to each other. The encounter can disrupt both systems and eject one or more stars at relatively high speeds.
The second idea involves a supernova explosion in a multiple star system. These powerful explosions can propel associated stars that didn’t explode along new paths, at much-higher speeds.
GD 50 might be from the Pleiades
One runaway star is GD 50, a white dwarf star with a bit more mass than our sun, but smaller than the Earth. A dime as dense as GD 50 would weigh 2,600 pounds (~1,200 kilos) on Earth.
GD 50 lies within the bounds of the constellation Eridanus the River. And in 2009, astronomers who’d been studying this star found that it moves through space in the same direction and at the same speed as the Pleiades star cluster. The Pleiades is not far from Eridanus on the sky’s dome. GD 50 is also about the same age as stars in the Pleiades. Therefore, astronomers concluded that GD 50 was born in the Pleiades, then flung out, possibly after passing too close to another star.
Some other runaway stars
Further examples of runaway stars are AE Aurigae, 53 Arietis and Mu Columbae. They’re all moving away from each other at velocities of over 100 km/s (for comparison, our sun moves through the Milky Way at only about 20 km/s faster than the local average).
Tracing their motions backwards on the sky’s dome, astronomers can see that — about 2 million years ago — the paths of these stars intersected near the Orion Nebula. There is a great loop or bubble of gas called Barnard’s Loop surrounding Orion’s three prominent Belt stars. Barnard’s Loop may be the remnant of the supernova that launched these stars as runaway stars.
4 runaway stars plowing through regions of dense interstellar gas and creating bright bow waves and trailing tails of glowing gas. The stars in these NASA Hubble Space Telescope images are among 14 young runaway stars spotted by Hubble’s Advanced Camera for Surveys between October 2005 and July 2006. Image via Hubblesite/ Wikimedia Commons.
Bottom line: Runaway stars move differently from the general stream of stars in our Milky Way galaxy. The most compelling evidence suggests they were kicked out from their original star clusters by encounters between pairs of binary stars or by a supernova explosion.
This Hubble Space Telescope image shows a cloud in space where new stars are forming called 30 Doradus, aka the Tarantula Nebula. The enlarged inset shows a star that appears to have been kicked out of the nebula. In the inset, an arrow points to the runaway star and a dashed arrow to its presumed direction of motion. Image via NASA.
A runaway star moves faster and in a different direction
The sun and all of the Milky Way’s stars are moving in orbit around the center of our galaxy. It’s more or less orderly … but astronomers have identified some Milky Way stars that are moving faster than expected, and often in a direction that seems unusual. They use the term runaway star to describe these renegades.
Stars form in clouds of gas and dust. Multiple stars form from a single cloud. Therefore, many Milky Way stars move through space in loose associations, or more tightly bound open star clusters. By tracking the motions of a runaway star, astronomers can sometimes determine its original stellar companion. And, sometimes, they can work out what must have happened to kick the star on a different and much faster path to these stars.
Astronomers point to 2 possible reasons for a runaway star
The first scenario involves two binary star systems — two systems, each containing two stars — that pass close to each other. The encounter can disrupt both systems and eject one or more stars at relatively high speeds.
The second idea involves a supernova explosion in a multiple star system. These powerful explosions can propel associated stars that didn’t explode along new paths, at much-higher speeds.
GD 50 might be from the Pleiades
One runaway star is GD 50, a white dwarf star with a bit more mass than our sun, but smaller than the Earth. A dime as dense as GD 50 would weigh 2,600 pounds (~1,200 kilos) on Earth.
GD 50 lies within the bounds of the constellation Eridanus the River. And in 2009, astronomers who’d been studying this star found that it moves through space in the same direction and at the same speed as the Pleiades star cluster. The Pleiades is not far from Eridanus on the sky’s dome. GD 50 is also about the same age as stars in the Pleiades. Therefore, astronomers concluded that GD 50 was born in the Pleiades, then flung out, possibly after passing too close to another star.
Some other runaway stars
Further examples of runaway stars are AE Aurigae, 53 Arietis and Mu Columbae. They’re all moving away from each other at velocities of over 100 km/s (for comparison, our sun moves through the Milky Way at only about 20 km/s faster than the local average).
Tracing their motions backwards on the sky’s dome, astronomers can see that — about 2 million years ago — the paths of these stars intersected near the Orion Nebula. There is a great loop or bubble of gas called Barnard’s Loop surrounding Orion’s three prominent Belt stars. Barnard’s Loop may be the remnant of the supernova that launched these stars as runaway stars.
4 runaway stars plowing through regions of dense interstellar gas and creating bright bow waves and trailing tails of glowing gas. The stars in these NASA Hubble Space Telescope images are among 14 young runaway stars spotted by Hubble’s Advanced Camera for Surveys between October 2005 and July 2006. Image via Hubblesite/ Wikimedia Commons.
Bottom line: Runaway stars move differently from the general stream of stars in our Milky Way galaxy. The most compelling evidence suggests they were kicked out from their original star clusters by encounters between pairs of binary stars or by a supernova explosion.
Artist’s concept of the redoubtable Voyager 1 spacecraft — most distant human-made object from Earth. Humanity launched it in 1977. It officially left our solar system in 2012, becoming the first to exit the heliosphere, or sphere of our sun’s influence. NASA said that at 12:16:07 a.m. CST on November 18, 2026, Voyager 1 will reach a distance of 1 light-day from Earth. Image via Caltech/ NASA-JPL.
Voyager 1 to reach 1 light-day from Earth in November
Voyager 1 is the most distant human-made object from Earth. It launched into space on September 5, 1977, and visited Jupiter and Saturn before heading out of the solar system. It officially crossed out of our solar system, passing the heliopause – the sphere of the sun’s influence – back in 2012. And at 12:16:07 a.m. CST on November 18, 2026, NASA said that Voyager 1 will reach a major milestone: 1 light-day from Earth. That’s the distance it takes light to travel in 24 hours.
This historic milestone of 1 light-day is equal to about 16.1 billion miles (25.9 billion kilometers), or 173.14 astronomical units (AU). As of early October, the Voyager 1 spacecraft is about 15.98 billion miles (25.72 billion km) away from Earth. If we could peer at Voyager 1 through a telescope on Earth, the light we see left the spacecraft 23 hours, 52 minutes and 30 seconds ago. On November 18, it will breach the 24-hour mark.
And how long did it take Voyager 1 to travel 1 light-day? It took 49 years, 2 months, and 11 days to travel that distance from Earth. Keep on reading for how to celebrate this milestone.
Voyager 1 is now outside our solar system. On November 18, 2026, it will reach 1 light-day distant from Earth. Image via NASA/ JPL-Caltech.
Here’s how to celebrate!
To mark Voyager 1’s milestone of 1 light-day distant, NASA is organizing a worldwide Shine Bright celebration. After sunset on Tuesday, November 17, people can participate by pointing a flashlight, phone, glow stick or other light toward the sky and flashing the letters V-G-R for Voyager in Morse code.
So how do you spell V-G-R in Morse code? V is dot, dot, dot, dash. G is dash, dash, dot. And R is dot, dash, dot. If that’s too complicated, you can just NASA’s automated flasher here.
NASA hopes the worldwide light display will celebrate humanity’s remarkable achievement in sending a spacecraft farther into space than anything else they’ve ever built.
What about Voyager 2?
And where is Voyager 2? You might know that Voyager 2 actually launched a few weeks before its sister craft. But while Voyager 1 only visited Jupiter and Saturn, Voyager 2 took a Grand Tour, visiting all the gas giant planets: Jupiter, Saturn, Uranus and Neptune. So it’s not as far from Earth as Voyager 1.
But it’s not too far behind, relatively speaking. Voyager 2 is about 2 billion miles (3.2 billion km) closer to Earth than Voyager 1. It’s also moving a bit slower, so it can never catch up. Besides, Voyager 1 and 2 are not headed in the same direction anyway. Voyager 1 is headed “up” out of the solar plane, while Voyager 2 is headed “down.” Voyager 1 is moving toward the direction of the constellation Ophiuchus. And Voyager 2 is headed in the direction of the constellation Andromeda.
So when will Voyager 2 reach a distance of 1 light-day from us? NASA said not for nine more years, in November 2035.
Are the Voyager spacecraft still functioning?
Both Voyager spacecraft are still in communication with Earth, even though that process takes approximately a day for one-way messages. But most of the instruments on the Voyagers are no longer working. Over the years, NASA has turned off one system after another in order to save power. Just this year, in April 2026, NASA turned off the Low-Energy Charged Particle (LECP) instrument to save energy. This instrument was detecting electrons, ions and cosmic rays in the interstellar medium. But NASA could still turn it on at some point in the future for new measurements.
Both Voyager spacecraft carry a golden record that is etched with images and sounds to represent life on Earth. The golden records were a largely symbolic gesture meant to represent Earth in the wider universe and with the off-chance that an alien civilization would one day find them and learn something of their origins. As Carl Sagan said:
The spacecraft will be encountered and the record played only if there are advanced space-faring civilizations in interstellar space, but the launching of this ‘bottle’ into the cosmic ‘ocean’ says something very hopeful about life on this planet.
Bottom line: The Voyager 1 spacecraft — which launched from Earth in 1977 — will reach 1 light-day from Earth on November 18, 2026. It is the first human-made object to travel that far from Earth.
Artist’s concept of the redoubtable Voyager 1 spacecraft — most distant human-made object from Earth. Humanity launched it in 1977. It officially left our solar system in 2012, becoming the first to exit the heliosphere, or sphere of our sun’s influence. NASA said that at 12:16:07 a.m. CST on November 18, 2026, Voyager 1 will reach a distance of 1 light-day from Earth. Image via Caltech/ NASA-JPL.
Voyager 1 to reach 1 light-day from Earth in November
Voyager 1 is the most distant human-made object from Earth. It launched into space on September 5, 1977, and visited Jupiter and Saturn before heading out of the solar system. It officially crossed out of our solar system, passing the heliopause – the sphere of the sun’s influence – back in 2012. And at 12:16:07 a.m. CST on November 18, 2026, NASA said that Voyager 1 will reach a major milestone: 1 light-day from Earth. That’s the distance it takes light to travel in 24 hours.
This historic milestone of 1 light-day is equal to about 16.1 billion miles (25.9 billion kilometers), or 173.14 astronomical units (AU). As of early October, the Voyager 1 spacecraft is about 15.98 billion miles (25.72 billion km) away from Earth. If we could peer at Voyager 1 through a telescope on Earth, the light we see left the spacecraft 23 hours, 52 minutes and 30 seconds ago. On November 18, it will breach the 24-hour mark.
And how long did it take Voyager 1 to travel 1 light-day? It took 49 years, 2 months, and 11 days to travel that distance from Earth. Keep on reading for how to celebrate this milestone.
Voyager 1 is now outside our solar system. On November 18, 2026, it will reach 1 light-day distant from Earth. Image via NASA/ JPL-Caltech.
Here’s how to celebrate!
To mark Voyager 1’s milestone of 1 light-day distant, NASA is organizing a worldwide Shine Bright celebration. After sunset on Tuesday, November 17, people can participate by pointing a flashlight, phone, glow stick or other light toward the sky and flashing the letters V-G-R for Voyager in Morse code.
So how do you spell V-G-R in Morse code? V is dot, dot, dot, dash. G is dash, dash, dot. And R is dot, dash, dot. If that’s too complicated, you can just NASA’s automated flasher here.
NASA hopes the worldwide light display will celebrate humanity’s remarkable achievement in sending a spacecraft farther into space than anything else they’ve ever built.
What about Voyager 2?
And where is Voyager 2? You might know that Voyager 2 actually launched a few weeks before its sister craft. But while Voyager 1 only visited Jupiter and Saturn, Voyager 2 took a Grand Tour, visiting all the gas giant planets: Jupiter, Saturn, Uranus and Neptune. So it’s not as far from Earth as Voyager 1.
But it’s not too far behind, relatively speaking. Voyager 2 is about 2 billion miles (3.2 billion km) closer to Earth than Voyager 1. It’s also moving a bit slower, so it can never catch up. Besides, Voyager 1 and 2 are not headed in the same direction anyway. Voyager 1 is headed “up” out of the solar plane, while Voyager 2 is headed “down.” Voyager 1 is moving toward the direction of the constellation Ophiuchus. And Voyager 2 is headed in the direction of the constellation Andromeda.
So when will Voyager 2 reach a distance of 1 light-day from us? NASA said not for nine more years, in November 2035.
Are the Voyager spacecraft still functioning?
Both Voyager spacecraft are still in communication with Earth, even though that process takes approximately a day for one-way messages. But most of the instruments on the Voyagers are no longer working. Over the years, NASA has turned off one system after another in order to save power. Just this year, in April 2026, NASA turned off the Low-Energy Charged Particle (LECP) instrument to save energy. This instrument was detecting electrons, ions and cosmic rays in the interstellar medium. But NASA could still turn it on at some point in the future for new measurements.
Both Voyager spacecraft carry a golden record that is etched with images and sounds to represent life on Earth. The golden records were a largely symbolic gesture meant to represent Earth in the wider universe and with the off-chance that an alien civilization would one day find them and learn something of their origins. As Carl Sagan said:
The spacecraft will be encountered and the record played only if there are advanced space-faring civilizations in interstellar space, but the launching of this ‘bottle’ into the cosmic ‘ocean’ says something very hopeful about life on this planet.
Bottom line: The Voyager 1 spacecraft — which launched from Earth in 1977 — will reach 1 light-day from Earth on November 18, 2026. It is the first human-made object to travel that far from Earth.
View larger. | Artist’s concept of super-Earth TOI-561 b. New observations by NASA’s James Webb Space Telescope show again that this distant world has a dense atmosphere. The atmosphere of lava planet TOI-561 b is highly reflective, suggesting clouds or haze. Image via CryoDragon Inc./ University of Birmingham.
The super-Earth exoplanet TOI-561 b is hot and its surface is likely covered by molten lava. An atmosphere for this lava planet was an unexpected discovery.
Additional observations using the Webb space telescope have re-confirmed the existence of this world’s dense atmosphere.
The new observations also show that the atmosphere of TOI-561 b is highly reflective, with clouds or haze.
Surprising atmosphere of lava planet TOI-561 b re-confirmed by Webb
Last December, scientists at the Carnegie Institution for Science in Washington, D.C. said rocky exoplanet TOI-561 b was a scorching hot super-Earth — a lava planet — with a thick atmosphere. It was a surprise, because scientists had thought it was too small and too close to its star to hold an atmosphere.
TOI-561 b is located some 280.5 light-years from Earth, in the direction of our constellation Sextans. It orbits extremely near its host star, completing a single orbit (a full “year”) in under 10.5 hours. Surface temperatures are estimated to be over 2,000 K (around 3,100°F / 1,700°C). At these extreme temperatures, rock melts, creating a global ocean of molten lava on its dayside.
Now we have an update on this fascinating world. Some of the same researchers that conducted the earlier study — led this time by the University of Montreal in Canada — said on October 27, 2026, that they used the James Webb Space Telescope to re-observe TOI-561 b. Their observations showed that there are clouds or haze in the atmosphere of this world. They also suggest it reflects much of the heat coming from the planet’s star back into space.
The researchers published their peer-reviewed findings in The Astronomical Journal on September 29, 2026.
And Evan Gough wrote about the latest observations for Universe Today on October 27, 2026.
A surprising atmosphere
TOI-561 b is what scientists call an ultra-short period (USP) planet. Even though it is a super-Earth, scientists thought that it was too small — and hot — to hold on to any atmosphere, due to being so close to its star.
But it seems that TOI-561 b does have an atmosphere, and a thick one at that. The paper states:
Ultrashort period (USP) rocky planets are expected to be depleted of any substantial gaseous envelope due to the intense irradiation they receive from their host star, making the recent detection of an atmosphere around TOI-561 b particularly surprising. That finding was based on the planet’s bulk density and dayside emission spectrum, but full-orbit phase-curve observations offer a more comprehensive way to constrain the presence and characteristics of a planet’s atmosphere.
View larger. | Emission spectrum of TOI-561 b from the James Webb Space Telescope. The data are consistent with an atmosphere rich in volatiles like water, oxygen and carbon dioxide. The model shown here assumes an atmosphere that is composed of 100% water vapor. Image via NASA/ ESA/ CSA/ Ralf Crawford (STScI); Science: Johanna Teske (Carnegie Science Earth and Planets Laboratory)/ Anjali Piette (University of Birmingham)/ Tim Lichtenberg (Groningen)/ Nicole Wallack (Carnegie Science Earth and Planets Laboratory).
The atmosphere of the lava planet is highly reflective
The researchers used Webb to observe TOI-561 b for 37 hours. That worked out to seeing three orbits of the planet, at 10.5 hours per orbit. That is good, because the more orbits that can be observed, the better for gathering data.
The previous observations had also shown that TOI-561 b has an atmosphere. How did the researchers determine this?
The dayside of the planet was a lot cooler than expected. That shouldn’t be the case if the planet had no atmosphere.
There were two possible explanations. Either heat was being reflected back into space or the atmosphere transported it to the nightside. But the results showed the nightside wasn’t warm enough. The researchers estimated that about 3/4 of the planet’s heat must be reflected into space. The paper states:
We conclude from the GCM simulations that heat redistribution alone cannot match the observed dayside fluxes or amplitude of the phase curve, and a high-albedo source (Ab = 0.6) indicative of clouds or haze.
Co-author Lisa Dang is the project lead at the University of Waterloo, Ontario, Canada. She explained:
We measured how the planet’s brightness and heat changed throughout its orbit. This technique, known as a phase curve, revealed that the planet reflects a significant amount of light from its star, and that heat is being redistributed around the planet instead of only on the sunlit side. Together, these point to the presence of an atmosphere.
Multiple kinds of clouds
The researchers said that clouds or haze are likely reflecting the heat. Silicon dioxide (SiO2) and magnesium metasilicate (MgSiO3) are two of the most likely compositions of the clouds. The paper states that:
… multiple possible cloud species can form on the dayside, including MgSiO3 and SiO2.
View larger. | Another artist’s concept of scorching hot TOI-561 b and its sunlike star. New observations by NASA’s James Webb Space Telescope show again there is a dense atmosphere on the planet. Image via NASA/ ESA/ CSA/ Ralf Crawford (STScI).
Challenging current theories
The findings are surprising, and they also challenge current theories about rocky ultra-short period planets. Dang said:
Our discovery challenges current theories. We would expect a heavily irradiated rocky planet like TOI-561 b to have lost its atmosphere billions of years ago. Instead, the evidence suggests it still has a significant atmosphere today.
And the paper states:
Atmospheric-escape theory suggests that strongly irradiated super-Earths should be devoid of any volatile envelopes. This is particularly astonishing given that the current JWST census of rocky exoplanets has been interpreted as suggestive of a population of bare-rock planets …
It’s also notable that TOI-561 b orbits a sun-like star. Most ultra-short period planets orbit red dwarfs. And red dwarfs are known for their bursts of deadly radiation. That radiation can strip the atmospheres off planets that are too close.
Yet TOI-561 b receives more radiation from its star than typical red dwarfs. And it still has an atmosphere! How is that possible?
Lisa Dang at the University of Waterloo is the project lead for the new study of TOI-561 b. Image via University of Waterloo.
How is the atmosphere of lava planet TOI-561 b possible?
The researchers aren’t sure how TOI-561 b has been able to keep its atmosphere. But they have ideas.
It might have started out with an even much thicker primordial atmosphere, perhaps as a sub-Neptune (larger than a super-Earth). The radiation might have indeed stripped away most or all of that atmosphere. So what’s left now is a secondary atmosphere.
It’s also possible that the planet originated much farther out from its star than where it is now. That would be when the star was still young. At that time, it emitted even more radiation.
When the planet migrated closer to the star, the star was already “calming down” and emitting less radiation. As a result, the remaining atmosphere was spared from destruction.
Or it could be that the answer lies in both scenarios.
But there’s another possibility, too. The planet “consumed” its original atmosphere. In other words, the atmosphere became trapped in the interior of the planet.
Co-author Anjali Piette, Assistant Professor in Astronomy at the University of Birmingham, said:
Our discovery challenges current theories. We would expect a heavily irradiated rocky planet like TOI-561 b to have lost its atmosphere billions of years ago. Instead, the evidence suggests it still has a significant atmosphere today. This raises major questions such as whether the planet started with an unusually large supply of gases or if the ocean of molten rock covering its surface acts as a planet-wide volcano that is constantly feeding its atmosphere.
View larger. | Artist’s concept of a lava planet. TOI-561 b orbits so close to its star that its surface is likely covered in molten lava. Image via ESO/ Wikimedia Commons.
Venus or Io?
The researchers want to know if TOI-561 b is more similar to Venus or Jupiter’s volcanic moon Io. Dang said:
The next big question we will seek to answer is whether TOI-561 b’s atmosphere resembles Venus or an extreme version of lo. Observing the planet at longer wavelengths with the JWST could give us insights and help explain how a planet this hot has held on to an atmosphere for billions of years.
The unexpected atmosphere of lava world TOI-561 b was a big surprise to astronomers. But it will also provide valuable data for studying other rocky super-Earth planets. How many other also have atmospheres, and what kind?
Bottom line: More recent observations of hot super-Earth TOI-561 b by the Webb space telescope show again that the lava planet’s surprising atmosphere does exist. And it’s very reflective.
View larger. | Artist’s concept of super-Earth TOI-561 b. New observations by NASA’s James Webb Space Telescope show again that this distant world has a dense atmosphere. The atmosphere of lava planet TOI-561 b is highly reflective, suggesting clouds or haze. Image via CryoDragon Inc./ University of Birmingham.
The super-Earth exoplanet TOI-561 b is hot and its surface is likely covered by molten lava. An atmosphere for this lava planet was an unexpected discovery.
Additional observations using the Webb space telescope have re-confirmed the existence of this world’s dense atmosphere.
The new observations also show that the atmosphere of TOI-561 b is highly reflective, with clouds or haze.
Surprising atmosphere of lava planet TOI-561 b re-confirmed by Webb
Last December, scientists at the Carnegie Institution for Science in Washington, D.C. said rocky exoplanet TOI-561 b was a scorching hot super-Earth — a lava planet — with a thick atmosphere. It was a surprise, because scientists had thought it was too small and too close to its star to hold an atmosphere.
TOI-561 b is located some 280.5 light-years from Earth, in the direction of our constellation Sextans. It orbits extremely near its host star, completing a single orbit (a full “year”) in under 10.5 hours. Surface temperatures are estimated to be over 2,000 K (around 3,100°F / 1,700°C). At these extreme temperatures, rock melts, creating a global ocean of molten lava on its dayside.
Now we have an update on this fascinating world. Some of the same researchers that conducted the earlier study — led this time by the University of Montreal in Canada — said on October 27, 2026, that they used the James Webb Space Telescope to re-observe TOI-561 b. Their observations showed that there are clouds or haze in the atmosphere of this world. They also suggest it reflects much of the heat coming from the planet’s star back into space.
The researchers published their peer-reviewed findings in The Astronomical Journal on September 29, 2026.
And Evan Gough wrote about the latest observations for Universe Today on October 27, 2026.
A surprising atmosphere
TOI-561 b is what scientists call an ultra-short period (USP) planet. Even though it is a super-Earth, scientists thought that it was too small — and hot — to hold on to any atmosphere, due to being so close to its star.
But it seems that TOI-561 b does have an atmosphere, and a thick one at that. The paper states:
Ultrashort period (USP) rocky planets are expected to be depleted of any substantial gaseous envelope due to the intense irradiation they receive from their host star, making the recent detection of an atmosphere around TOI-561 b particularly surprising. That finding was based on the planet’s bulk density and dayside emission spectrum, but full-orbit phase-curve observations offer a more comprehensive way to constrain the presence and characteristics of a planet’s atmosphere.
View larger. | Emission spectrum of TOI-561 b from the James Webb Space Telescope. The data are consistent with an atmosphere rich in volatiles like water, oxygen and carbon dioxide. The model shown here assumes an atmosphere that is composed of 100% water vapor. Image via NASA/ ESA/ CSA/ Ralf Crawford (STScI); Science: Johanna Teske (Carnegie Science Earth and Planets Laboratory)/ Anjali Piette (University of Birmingham)/ Tim Lichtenberg (Groningen)/ Nicole Wallack (Carnegie Science Earth and Planets Laboratory).
The atmosphere of the lava planet is highly reflective
The researchers used Webb to observe TOI-561 b for 37 hours. That worked out to seeing three orbits of the planet, at 10.5 hours per orbit. That is good, because the more orbits that can be observed, the better for gathering data.
The previous observations had also shown that TOI-561 b has an atmosphere. How did the researchers determine this?
The dayside of the planet was a lot cooler than expected. That shouldn’t be the case if the planet had no atmosphere.
There were two possible explanations. Either heat was being reflected back into space or the atmosphere transported it to the nightside. But the results showed the nightside wasn’t warm enough. The researchers estimated that about 3/4 of the planet’s heat must be reflected into space. The paper states:
We conclude from the GCM simulations that heat redistribution alone cannot match the observed dayside fluxes or amplitude of the phase curve, and a high-albedo source (Ab = 0.6) indicative of clouds or haze.
Co-author Lisa Dang is the project lead at the University of Waterloo, Ontario, Canada. She explained:
We measured how the planet’s brightness and heat changed throughout its orbit. This technique, known as a phase curve, revealed that the planet reflects a significant amount of light from its star, and that heat is being redistributed around the planet instead of only on the sunlit side. Together, these point to the presence of an atmosphere.
Multiple kinds of clouds
The researchers said that clouds or haze are likely reflecting the heat. Silicon dioxide (SiO2) and magnesium metasilicate (MgSiO3) are two of the most likely compositions of the clouds. The paper states that:
… multiple possible cloud species can form on the dayside, including MgSiO3 and SiO2.
View larger. | Another artist’s concept of scorching hot TOI-561 b and its sunlike star. New observations by NASA’s James Webb Space Telescope show again there is a dense atmosphere on the planet. Image via NASA/ ESA/ CSA/ Ralf Crawford (STScI).
Challenging current theories
The findings are surprising, and they also challenge current theories about rocky ultra-short period planets. Dang said:
Our discovery challenges current theories. We would expect a heavily irradiated rocky planet like TOI-561 b to have lost its atmosphere billions of years ago. Instead, the evidence suggests it still has a significant atmosphere today.
And the paper states:
Atmospheric-escape theory suggests that strongly irradiated super-Earths should be devoid of any volatile envelopes. This is particularly astonishing given that the current JWST census of rocky exoplanets has been interpreted as suggestive of a population of bare-rock planets …
It’s also notable that TOI-561 b orbits a sun-like star. Most ultra-short period planets orbit red dwarfs. And red dwarfs are known for their bursts of deadly radiation. That radiation can strip the atmospheres off planets that are too close.
Yet TOI-561 b receives more radiation from its star than typical red dwarfs. And it still has an atmosphere! How is that possible?
Lisa Dang at the University of Waterloo is the project lead for the new study of TOI-561 b. Image via University of Waterloo.
How is the atmosphere of lava planet TOI-561 b possible?
The researchers aren’t sure how TOI-561 b has been able to keep its atmosphere. But they have ideas.
It might have started out with an even much thicker primordial atmosphere, perhaps as a sub-Neptune (larger than a super-Earth). The radiation might have indeed stripped away most or all of that atmosphere. So what’s left now is a secondary atmosphere.
It’s also possible that the planet originated much farther out from its star than where it is now. That would be when the star was still young. At that time, it emitted even more radiation.
When the planet migrated closer to the star, the star was already “calming down” and emitting less radiation. As a result, the remaining atmosphere was spared from destruction.
Or it could be that the answer lies in both scenarios.
But there’s another possibility, too. The planet “consumed” its original atmosphere. In other words, the atmosphere became trapped in the interior of the planet.
Co-author Anjali Piette, Assistant Professor in Astronomy at the University of Birmingham, said:
Our discovery challenges current theories. We would expect a heavily irradiated rocky planet like TOI-561 b to have lost its atmosphere billions of years ago. Instead, the evidence suggests it still has a significant atmosphere today. This raises major questions such as whether the planet started with an unusually large supply of gases or if the ocean of molten rock covering its surface acts as a planet-wide volcano that is constantly feeding its atmosphere.
View larger. | Artist’s concept of a lava planet. TOI-561 b orbits so close to its star that its surface is likely covered in molten lava. Image via ESO/ Wikimedia Commons.
Venus or Io?
The researchers want to know if TOI-561 b is more similar to Venus or Jupiter’s volcanic moon Io. Dang said:
The next big question we will seek to answer is whether TOI-561 b’s atmosphere resembles Venus or an extreme version of lo. Observing the planet at longer wavelengths with the JWST could give us insights and help explain how a planet this hot has held on to an atmosphere for billions of years.
The unexpected atmosphere of lava world TOI-561 b was a big surprise to astronomers. But it will also provide valuable data for studying other rocky super-Earth planets. How many other also have atmospheres, and what kind?
Bottom line: More recent observations of hot super-Earth TOI-561 b by the Webb space telescope show again that the lava planet’s surprising atmosphere does exist. And it’s very reflective.
The Summer Triangle is a famous asterism, consisting of 3 bright stars. These stars are overhead in summer. But you can also easily see them through the northern autumn. Chart via EarthSky.
The Summer Triangle in autumn
The Summer Triangle isn’t a constellation. It’s an asterism, an obvious pattern or group of stars with a popular name. The Summer Triangle consists of three bright stars in three separate constellations.
The Summer Triangle is the signature star formation in the Northern Hemisphere’s summer sky. However, as the Septemberequinox comes and goes – and as the weeks of autumn begin to slide by – you’ll continue to notice this famous trio of stars.
You’ll find the Summer Triangle in November and December. Look for it tonight in the early evening. Look west!
In early November, the Summer Triangle is high in the western sky around mid-evening. Image via WyoAstro All-sky camera.
The 3 stars of the Summer Triangle
The brightest of the three stars is Vega is in the constellation Lyra the Harp. It’s the 5th-brightest star in our night sky. You’ll recognize Vega for its blue-white color. This star is located 25 light-years away.
Next in brightness is the star Altair is in Aquila the Eagle. Its only 16.7 light-years away. You’ll recognize Altair becuase it’s flanked closely by two fainter stars.
Deneb — in Cygnus the Swan — is the faintest of the Summer Triangle stars. But it has good reason to be faintest to our eye, because Deneb is one of the most distant stars we see with the unaided eye. It’s a luminous supergiant star, located roughly 1,400 to 2,600 light–years from Earth.
When is it visible in the evening sky
In the month of June – around the June solstice – the Summer Triangle pops out in the east as darkness falls and shines all night long. But now – after sunset in November – the Summer Triangle appears high in the western evening sky. As evening deepens, the Summer Triangle descends westward, with all three of its stars staying above the horizon until mid-to-late evening.
Altair – the Summer Triangle’s southernmost star – will set around 10 to 11 p.m. in November at mid-northern latitudes. Notice where you see the Summer Triangle at a given time this evening. The Summer Triangle will return to this same place in the sky some four minutes earlier with each passing day, or two hours earlier with each passing month.
Bottom line: Look westward this evening for the three brilliant stars of the Summer Triangle: Vega, Deneb and Altair.
The Summer Triangle is a famous asterism, consisting of 3 bright stars. These stars are overhead in summer. But you can also easily see them through the northern autumn. Chart via EarthSky.
The Summer Triangle in autumn
The Summer Triangle isn’t a constellation. It’s an asterism, an obvious pattern or group of stars with a popular name. The Summer Triangle consists of three bright stars in three separate constellations.
The Summer Triangle is the signature star formation in the Northern Hemisphere’s summer sky. However, as the Septemberequinox comes and goes – and as the weeks of autumn begin to slide by – you’ll continue to notice this famous trio of stars.
You’ll find the Summer Triangle in November and December. Look for it tonight in the early evening. Look west!
In early November, the Summer Triangle is high in the western sky around mid-evening. Image via WyoAstro All-sky camera.
The 3 stars of the Summer Triangle
The brightest of the three stars is Vega is in the constellation Lyra the Harp. It’s the 5th-brightest star in our night sky. You’ll recognize Vega for its blue-white color. This star is located 25 light-years away.
Next in brightness is the star Altair is in Aquila the Eagle. Its only 16.7 light-years away. You’ll recognize Altair becuase it’s flanked closely by two fainter stars.
Deneb — in Cygnus the Swan — is the faintest of the Summer Triangle stars. But it has good reason to be faintest to our eye, because Deneb is one of the most distant stars we see with the unaided eye. It’s a luminous supergiant star, located roughly 1,400 to 2,600 light–years from Earth.
When is it visible in the evening sky
In the month of June – around the June solstice – the Summer Triangle pops out in the east as darkness falls and shines all night long. But now – after sunset in November – the Summer Triangle appears high in the western evening sky. As evening deepens, the Summer Triangle descends westward, with all three of its stars staying above the horizon until mid-to-late evening.
Altair – the Summer Triangle’s southernmost star – will set around 10 to 11 p.m. in November at mid-northern latitudes. Notice where you see the Summer Triangle at a given time this evening. The Summer Triangle will return to this same place in the sky some four minutes earlier with each passing day, or two hours earlier with each passing month.
Bottom line: Look westward this evening for the three brilliant stars of the Summer Triangle: Vega, Deneb and Altair.
