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Delta Aquariid meteor shower: All you need to know in 2025

Meteor shower chart: Star chart with radial arrows from a spot below Great Square of Pegasus and above Fomalhaut.
The radiant point for the Delta Aquariids meteor shower is near the faint star Skat, or Delta Aquarii. It rises in mid-evening, is highest around 2 a.m. and low in the sky by dawn. Use the bright nearby star Fomalhaut to guide you to the Delta Aquariid radiant point. Find Fomalhaut by drawing a line southward through the stars on the west side of the Great Square of Pegasus. This chart shows a wide area, from overhead to southward, as seen from the Northern Hemisphere. From the Southern Hemisphere, the radiant is closer to overhead.

Delta Aquariid meteor shower

Every year, two meteor showers – the famous Perseids and the lesser known Delta Aquariids – converge in late summer.

Predicted peak: The peak is predicted** for 21 UTC on July 30, 2025. But this shower doesn’t have a noticeable peak. It rambles along steadily from late July through early August, joining forces with the August Perseids.
When to watch: Watch late July through early August, mid-evening to dawn.
Duration of shower: July 18 to August 21.
Radiant: Rises in mid-evening, highest around 2 a.m. and low in the sky by dawn. See chart above.
Nearest moon phase: In 2025, 1st quarter moon falls at 12:41 UTC on August 1. Take advantage of the moon-free evenings – after midnight – in late July for watching the Delta Aquariids (and the early Perseids).
Expected meteors at peak, under ideal conditions: The Delta Aquariids’ maximum hourly rate can reach 15 to 20 meteors in a dark sky with no moon. As a result, you’ll typically see plenty of Delta Aquariids mixed in with the Perseids, if you’re watching in early August.
Note: Like May’s Eta Aquariids, July’s Delta Aquariids favors the Southern Hemisphere. Skywatchers at high northern latitudes tend to discount it. The shower can be excellent, however, from latitudes like those in the southern U.S. Delta Aquariid meteors tend to be fainter than Perseid meteors. So a moon-free dark sky is essential. About 5% to 10% of the Delta Aquariid meteors leave persistent trains, glowing ionized gas trails that last a second or two after the meteor has passed.

Report a fireball (very bright meteor) to the American Meteor Society: it’s fun and easy!

The Delta Aquariid’s parent comet

From the late, great Don Machholz,(1952-2022), who discovered 12 comets …

The Delta Aquariid meteor shower’s parent comet comes from the 96P/Machholz Complex.

The 96P/Machholz Complex is a collection of eight meteor showers, including the Delta Aquariids, plus two comet groups (Marsden and Kracht), and at least one asteroid (2003 EH1). These meteors showers, and these comets, appear to share a common origin (although they’ve now diverged slightly in their orbits around the sun).

They are all related to the comet known as 96P/Machholz, which I discovered on May 12, 1986, from Loma Prieta Mountain in California.

At discovery, the comet was magnitude 10 and 2 degrees south of the Andromeda galaxy. I was using my 6-inch homemade binoculars for this find. Read the story of the discovery.

As a matter of fact, scientists had suspected the existence of the 96P/Machholz Complex in 2003. Finally, they fully described it in 2005, after conducting more studies.

A changing orbit

Comet 96P/Machholz orbits the sun every 5.3 years and gets eight times closer to the sun than we are. That is, its perihelion distance is 0.12 astronomical units (AU). One AU is the distance between the Earth and the sun. So, this comet comes well inside the orbit of Mercury. Over the course of 4,000 years, the comet’s orbit changes in shape and tilt, so that it leaves particles throughout the inner solar system. It gets around!

A recent study suggests that the material causing the Delta Aquariid meteor shower left the comet’s nucleus about 20,000 years ago. So, basically it’s old dust streaking across our skies.

Starry background, largish bright dot with 2 long, bright, fuzzy tails.
The late, great Don Machholz discovered comet 96P Machholz, the parent of the Delta Aquariid meteor shower, on May 12, 1986. This 2007 image is from the HI-2 camera of the STEREO-A spacecraft. Image via NASA/ Wikimedia Commons.

Perseid? Or Delta Aquariid?

Perseid and Delta Aquariid meteors fly in our skies at the same time of year. How can you tell them apart? This is where the concept of a radiant point comes in handy. Indeed, if you trace all the Delta Aquariid meteors backward, they appear to radiate from a certain point in front of the constellation Aquarius, which, as viewed from the Northern Hemisphere, arcs across the southern sky.

Meanwhile, the Perseids radiate from the constellation Perseus, in the northeast to high in the north between midnight and dawn as seen in Northern Hemisphere skies.

So – assuming you’re in the Northern Hemisphere, and watching around midnight or after – if you’re watching the Perseids and you see meteors coming from the northeast or north … they are Perseids. If you see them coming from the south … they are Delta Aquariids. In a particularly rich year for meteors, if you have a dark sky, you might even see them cross paths!

Consequently, it can be an awesome display.

Delta Aquariid meteor shower photos from the EarthSky community

Submit your night sky photos to EarthSky here

Several thin bright lines in a dark starry sky abpve silhouetted hills.
View at EarthSky Community Photos. | Bass Seckin in Bursa, Turkey, captured these meteors on July 29, 2020, and wrote: “Bursa is a 3 million populated city located in northwestern Turkey. It’s almost impossible to see meteors there … I went 100 kilometers (60 miles) out eastward for excluding light pollution. Interestingly I had seen only 1 or 2 meteors with unaided eye, but when checked frames I have seen that there were 4 to 6 meteors on single frame. The reddish spot at the center of the image is Mars, and Delta Aquariids meteors’ traces are from upper right corner toward bottom.” Thank you, Bass!
Slash of white light alongside cloudy band of Milky Way in densely starry sky.
View at EarthSky Community Photos. | James Reynolds in Asheville, North Carolina, captured this photo of a meteor on August 11, 2021. He wrote: “I am unsure whether this is a Perseid or a Delta Aquariid, but it is the 2nd largest meteor I’ve captured an image of (1st being what became an EarthSky photo of the day from last year’s Leonid meteor shower). You can see some clouds in this image, and they are going to get thicker where I am over the next few days, so I am glad I spent an hour outside early this morning to observe and photograph the meteor shower, and particularly grateful for this little gift from the universe.” Thank you, James!

Bottom line: The peak of the Delta Aquariid meteor shower is late July. But the shower rambles along steadily in late July and August, intermingling with the Perseids. In 2025, watch in the moon-free evenings – after midnight – of late July to avoid moonlight.

**Predicted peak times and dates for meteor showers are from the American Meteor Society. Note that meteor shower peak times can vary.

Everything you need to know: Perseid meteor shower

Meteor showers: Tips for watching the show

EarthSky’s meteor shower guide

Learn how to shoot photos of meteors

The post Delta Aquariid meteor shower: All you need to know in 2025 first appeared on EarthSky.



from EarthSky https://ift.tt/JW0xvHS
Meteor shower chart: Star chart with radial arrows from a spot below Great Square of Pegasus and above Fomalhaut.
The radiant point for the Delta Aquariids meteor shower is near the faint star Skat, or Delta Aquarii. It rises in mid-evening, is highest around 2 a.m. and low in the sky by dawn. Use the bright nearby star Fomalhaut to guide you to the Delta Aquariid radiant point. Find Fomalhaut by drawing a line southward through the stars on the west side of the Great Square of Pegasus. This chart shows a wide area, from overhead to southward, as seen from the Northern Hemisphere. From the Southern Hemisphere, the radiant is closer to overhead.

Delta Aquariid meteor shower

Every year, two meteor showers – the famous Perseids and the lesser known Delta Aquariids – converge in late summer.

Predicted peak: The peak is predicted** for 21 UTC on July 30, 2025. But this shower doesn’t have a noticeable peak. It rambles along steadily from late July through early August, joining forces with the August Perseids.
When to watch: Watch late July through early August, mid-evening to dawn.
Duration of shower: July 18 to August 21.
Radiant: Rises in mid-evening, highest around 2 a.m. and low in the sky by dawn. See chart above.
Nearest moon phase: In 2025, 1st quarter moon falls at 12:41 UTC on August 1. Take advantage of the moon-free evenings – after midnight – in late July for watching the Delta Aquariids (and the early Perseids).
Expected meteors at peak, under ideal conditions: The Delta Aquariids’ maximum hourly rate can reach 15 to 20 meteors in a dark sky with no moon. As a result, you’ll typically see plenty of Delta Aquariids mixed in with the Perseids, if you’re watching in early August.
Note: Like May’s Eta Aquariids, July’s Delta Aquariids favors the Southern Hemisphere. Skywatchers at high northern latitudes tend to discount it. The shower can be excellent, however, from latitudes like those in the southern U.S. Delta Aquariid meteors tend to be fainter than Perseid meteors. So a moon-free dark sky is essential. About 5% to 10% of the Delta Aquariid meteors leave persistent trains, glowing ionized gas trails that last a second or two after the meteor has passed.

Report a fireball (very bright meteor) to the American Meteor Society: it’s fun and easy!

The Delta Aquariid’s parent comet

From the late, great Don Machholz,(1952-2022), who discovered 12 comets …

The Delta Aquariid meteor shower’s parent comet comes from the 96P/Machholz Complex.

The 96P/Machholz Complex is a collection of eight meteor showers, including the Delta Aquariids, plus two comet groups (Marsden and Kracht), and at least one asteroid (2003 EH1). These meteors showers, and these comets, appear to share a common origin (although they’ve now diverged slightly in their orbits around the sun).

They are all related to the comet known as 96P/Machholz, which I discovered on May 12, 1986, from Loma Prieta Mountain in California.

At discovery, the comet was magnitude 10 and 2 degrees south of the Andromeda galaxy. I was using my 6-inch homemade binoculars for this find. Read the story of the discovery.

As a matter of fact, scientists had suspected the existence of the 96P/Machholz Complex in 2003. Finally, they fully described it in 2005, after conducting more studies.

A changing orbit

Comet 96P/Machholz orbits the sun every 5.3 years and gets eight times closer to the sun than we are. That is, its perihelion distance is 0.12 astronomical units (AU). One AU is the distance between the Earth and the sun. So, this comet comes well inside the orbit of Mercury. Over the course of 4,000 years, the comet’s orbit changes in shape and tilt, so that it leaves particles throughout the inner solar system. It gets around!

A recent study suggests that the material causing the Delta Aquariid meteor shower left the comet’s nucleus about 20,000 years ago. So, basically it’s old dust streaking across our skies.

Starry background, largish bright dot with 2 long, bright, fuzzy tails.
The late, great Don Machholz discovered comet 96P Machholz, the parent of the Delta Aquariid meteor shower, on May 12, 1986. This 2007 image is from the HI-2 camera of the STEREO-A spacecraft. Image via NASA/ Wikimedia Commons.

Perseid? Or Delta Aquariid?

Perseid and Delta Aquariid meteors fly in our skies at the same time of year. How can you tell them apart? This is where the concept of a radiant point comes in handy. Indeed, if you trace all the Delta Aquariid meteors backward, they appear to radiate from a certain point in front of the constellation Aquarius, which, as viewed from the Northern Hemisphere, arcs across the southern sky.

Meanwhile, the Perseids radiate from the constellation Perseus, in the northeast to high in the north between midnight and dawn as seen in Northern Hemisphere skies.

So – assuming you’re in the Northern Hemisphere, and watching around midnight or after – if you’re watching the Perseids and you see meteors coming from the northeast or north … they are Perseids. If you see them coming from the south … they are Delta Aquariids. In a particularly rich year for meteors, if you have a dark sky, you might even see them cross paths!

Consequently, it can be an awesome display.

Delta Aquariid meteor shower photos from the EarthSky community

Submit your night sky photos to EarthSky here

Several thin bright lines in a dark starry sky abpve silhouetted hills.
View at EarthSky Community Photos. | Bass Seckin in Bursa, Turkey, captured these meteors on July 29, 2020, and wrote: “Bursa is a 3 million populated city located in northwestern Turkey. It’s almost impossible to see meteors there … I went 100 kilometers (60 miles) out eastward for excluding light pollution. Interestingly I had seen only 1 or 2 meteors with unaided eye, but when checked frames I have seen that there were 4 to 6 meteors on single frame. The reddish spot at the center of the image is Mars, and Delta Aquariids meteors’ traces are from upper right corner toward bottom.” Thank you, Bass!
Slash of white light alongside cloudy band of Milky Way in densely starry sky.
View at EarthSky Community Photos. | James Reynolds in Asheville, North Carolina, captured this photo of a meteor on August 11, 2021. He wrote: “I am unsure whether this is a Perseid or a Delta Aquariid, but it is the 2nd largest meteor I’ve captured an image of (1st being what became an EarthSky photo of the day from last year’s Leonid meteor shower). You can see some clouds in this image, and they are going to get thicker where I am over the next few days, so I am glad I spent an hour outside early this morning to observe and photograph the meteor shower, and particularly grateful for this little gift from the universe.” Thank you, James!

Bottom line: The peak of the Delta Aquariid meteor shower is late July. But the shower rambles along steadily in late July and August, intermingling with the Perseids. In 2025, watch in the moon-free evenings – after midnight – of late July to avoid moonlight.

**Predicted peak times and dates for meteor showers are from the American Meteor Society. Note that meteor shower peak times can vary.

Everything you need to know: Perseid meteor shower

Meteor showers: Tips for watching the show

EarthSky’s meteor shower guide

Learn how to shoot photos of meteors

The post Delta Aquariid meteor shower: All you need to know in 2025 first appeared on EarthSky.



from EarthSky https://ift.tt/JW0xvHS

Radiant point of meteor showers: All you need to know

Radiant point: Ten thin white streaks of different lengths radiating out from a white O in a dark sky.
Meteors in annual showers have a radiant point, a point in the sky from which all the meteors appear to radiate, marked by an O in this image from Wikimedia Commons (CC BY-SA 3.0).

Meteor showers have a radiant point

Many times each year, when Earth passes through the orbital path of a comet, we see streaks in a dark night sky: a meteor shower! The meteors are cometary debris – icy, dusty particles, called meteoroids – vaporizing in Earth’s upper atmosphere. Often, you’ll hear astronomers speak of a meteor shower’s radiant point. And many people ask how to find a shower’s radiant point in the night sky.

What is the radiant point? Do you really need to find it to enjoy a meteor shower?

Fording the meteor stream

Let’s start with what it is. Remember, meteor showers happen as Earth moves through space, when we pass through the orbit of a comet. Comets are icy, dusty objects. And they litter their orbits with debris. The stream of cometary particles in space is called a meteor stream.

So crossing a meteor stream is much like walking sideways to extremely high winds on Earth. The wind (or comet dust) is all around you. You’re surrounded by wind (or dust), but it’s striking you on only one side of your body, the side facing into the force of the blowing wind. Smack! The oncoming wind might feel like a big hand trying to push you over. If you switch direction, the force and impact of the wind changes, based upon the wind’s speed and direction and your speed and direction.

Hitting Earth on 1 side

Likewise, when Earth is fording a meteor stream in space, bits of comet dust are all around us. But they’re striking Earth only on one side, determined by a combination of the meteor stream’s speed and direction and Earth’s speed and direction. Most meteor showers occur after midnight, when Earth’s spin has turned into the oncoming meteor stream. Earth’s forward motion added to the meteors’ motion makes for some very swift meteors. But some showers, like the annual Draconids and Tau Herculids, approach the Earth from behind in our evening sky. Then the meteors have to catch up to us, resulting in slow meteors.

So – as you watch a meteor shower – you’re watching bits of dust strike Earth’s atmosphere on parallel paths, as illustrated below.

Diagram of Earth orbit with Earth passing through a wide arc of tiny green dots representing cometary debris.
Meteors in annual showers happen when Earth encounters debris left behind by a comet. Astronomers have investigated the various streams of debris in space left behind by comets in their passages near the sun. As Earth moves through a stream of cometary debris, the bits of comet dust enter our atmosphere on parallel paths. Image by AstroBob. Used with permission.

A 2nd analogy

Now imagine yourself on Earth looking up at the meteors. You can’t tell it just by looking at one meteor, but the meteors you see are indeed coming at you on parallel paths. And so we see the paths of the meteors converge at a single point in our sky: the radiant point. It’s like standing on railroad tracks and seeing the tracks converge in the distance. Do the tracks really converge? Nope. They stay parallel to one another and only appear to converge.

A meteor shower’s radiant point is much the same illusion as railroad tracks appearing to converge in the distance.

Of course, meteors have nothing whatever to do with railroad tracks. The meteors burn up some 60 miles (100 km) above Earth’s surface. The railroad tracks are right here on Earth. Caution: do not hang out at the railroad tracks thinking they will bring you more meteors. They won’t. Also, standing on railroad tracks is dangerous.

View of train tracks wide apart close to you and close together in the distance.
When you stand on a railroad track, you see the illusion of tracks converging in the distance. Likewise, the paths of meteors in a single meteor shower appear to converge at a point – the radiant point – on the sky’s dome. Image via Shane Hoving/ Unsplash.

Hey! Who moved my railroad tracks?

The radiant point of meteor showers is fixed. Prepare to be shocked. Ok, ready?

The radiant moves.

This is a little-known fact. It’s surprising because we often see charts showing the location of radiant points with respect to this or that constellation. But those charts are set for the night of the shower’s peak.

You might be asking: Why hasn’t anyone told me this before? We don’t know! Many long-time meteor observers are surprised to hear this. It happens as Earth moves around the sun. A meteor shower radiant typically moves about 1 degree per day eastward, and approximately parallel to the ecliptic. A map showing the radiant shift of the Delta Aquariids meteor shower is below.

Star chart with stars and constellations and a short yellow arrow with dates at beginning, middle, and end.
The drift of the Delta Aquariid radiant from July 20 through August 9. Map via Don Machholz.

Tip: Don’t stare solely at the radiant

People always want to know how they can find meteor shower radiant points in the night sky. But when you watch a meteor shower, you shouldn’t be staring the whole time at the radiant. Most meteors don’t become visible until they’re some distance from the radiant. So when you’re watching a shower, try looking to the side of the radiant – about 45 degrees off – in all directions on the sky’s dome.

Tip: Know your radiant point rising times

However, there is something important to know about meteor shower radiant points. You’ll start seeing more meteors after the radiant rises into your sky. Most (but not all) meteor showers are best after midnight. That’s because their radiant points don’t rise until midnight or after. The rare and infrequent meteors you might see before the radiant rises will be Earth grazers, which start below your horizon and then trace long paths across your sky.

You’ll also see the most meteors when the radiant is highest in your sky. That’s why the Perseids, for example, are best just before dawn. The radiant for the Perseids rises in the middle of the night for everyone around the globe. And, for all of us, the Perseids’ radiant is highest before dawn. Then the meteors are raining down from the top of the sky. Awesome!

So, if you want to watch a meteor shower, find out what time the radiant point for that shower rises. And then determine when it reaches its highest point in the night sky. You’ll see lots more meteors that way!

Starry sky with dozens of thin radial streaks above silhouetted evergreen trees.
View at EarthSky Community Photos. | David Cox captured a Tau Herculid meteor display – all shooting away from the radiant point – in this image. He wrote: “Composite of 25 meteor streaks captured over 68 minutes during the May 31, 2022, Tau Herculid meteor shower. Although the potential meteor storm did not transpire, there were numerous short meteor streaks visible under the dark sky to provide good viewing entertainment.” Thank you, David!

Tip: Watch for loooong meteors, far from the radiant

Here is one more thing. The meteor paths are generally longer the farther you look from the radiant. This is obvious in the image below. The shorter paths are near the radiant. If you see a short flash during a meteor shower, it is just a meteor headed in your direction. But don’t worry, the comet fluff does not make it to the ground.

Plenty of pink and green straight lines (meteors) radiating from same place in a dark, starry sky.
The Perseid meteor shower and its radiant, which is near the center of this photo. The Andromeda galaxy is near the bottom of the image. Image via NASA.

The radiant point and meteor shower names

By the way, meteor shower radiant points are important for another reason. The shower typically takes its name from the constellation containing the radiant point during the time of the shower’s peak. When several meteor showers share the same constellation, then the closest star gets tagged for the name.

Draconids, Lyrids, Eta and Delta Aquariids, Perseids, Leonids, Geminids … You get the idea!

Bottom line: Meteors enter Earth’s atmosphere on parallel paths. So – just as when you stand on a railroad track, you see the tracks converge in the distance – you’ll see meteors appear to come from a single point in the sky: the radiant point!

Read about all the major meteor showers: EarthSky’s meteor shower guide

How high up are meteors when they begin to glow?

Read more: Meteor showers are here! 10 easy tips for watching

The post Radiant point of meteor showers: All you need to know first appeared on EarthSky.



from EarthSky https://ift.tt/ZQeU734
Radiant point: Ten thin white streaks of different lengths radiating out from a white O in a dark sky.
Meteors in annual showers have a radiant point, a point in the sky from which all the meteors appear to radiate, marked by an O in this image from Wikimedia Commons (CC BY-SA 3.0).

Meteor showers have a radiant point

Many times each year, when Earth passes through the orbital path of a comet, we see streaks in a dark night sky: a meteor shower! The meteors are cometary debris – icy, dusty particles, called meteoroids – vaporizing in Earth’s upper atmosphere. Often, you’ll hear astronomers speak of a meteor shower’s radiant point. And many people ask how to find a shower’s radiant point in the night sky.

What is the radiant point? Do you really need to find it to enjoy a meteor shower?

Fording the meteor stream

Let’s start with what it is. Remember, meteor showers happen as Earth moves through space, when we pass through the orbit of a comet. Comets are icy, dusty objects. And they litter their orbits with debris. The stream of cometary particles in space is called a meteor stream.

So crossing a meteor stream is much like walking sideways to extremely high winds on Earth. The wind (or comet dust) is all around you. You’re surrounded by wind (or dust), but it’s striking you on only one side of your body, the side facing into the force of the blowing wind. Smack! The oncoming wind might feel like a big hand trying to push you over. If you switch direction, the force and impact of the wind changes, based upon the wind’s speed and direction and your speed and direction.

Hitting Earth on 1 side

Likewise, when Earth is fording a meteor stream in space, bits of comet dust are all around us. But they’re striking Earth only on one side, determined by a combination of the meteor stream’s speed and direction and Earth’s speed and direction. Most meteor showers occur after midnight, when Earth’s spin has turned into the oncoming meteor stream. Earth’s forward motion added to the meteors’ motion makes for some very swift meteors. But some showers, like the annual Draconids and Tau Herculids, approach the Earth from behind in our evening sky. Then the meteors have to catch up to us, resulting in slow meteors.

So – as you watch a meteor shower – you’re watching bits of dust strike Earth’s atmosphere on parallel paths, as illustrated below.

Diagram of Earth orbit with Earth passing through a wide arc of tiny green dots representing cometary debris.
Meteors in annual showers happen when Earth encounters debris left behind by a comet. Astronomers have investigated the various streams of debris in space left behind by comets in their passages near the sun. As Earth moves through a stream of cometary debris, the bits of comet dust enter our atmosphere on parallel paths. Image by AstroBob. Used with permission.

A 2nd analogy

Now imagine yourself on Earth looking up at the meteors. You can’t tell it just by looking at one meteor, but the meteors you see are indeed coming at you on parallel paths. And so we see the paths of the meteors converge at a single point in our sky: the radiant point. It’s like standing on railroad tracks and seeing the tracks converge in the distance. Do the tracks really converge? Nope. They stay parallel to one another and only appear to converge.

A meteor shower’s radiant point is much the same illusion as railroad tracks appearing to converge in the distance.

Of course, meteors have nothing whatever to do with railroad tracks. The meteors burn up some 60 miles (100 km) above Earth’s surface. The railroad tracks are right here on Earth. Caution: do not hang out at the railroad tracks thinking they will bring you more meteors. They won’t. Also, standing on railroad tracks is dangerous.

View of train tracks wide apart close to you and close together in the distance.
When you stand on a railroad track, you see the illusion of tracks converging in the distance. Likewise, the paths of meteors in a single meteor shower appear to converge at a point – the radiant point – on the sky’s dome. Image via Shane Hoving/ Unsplash.

Hey! Who moved my railroad tracks?

The radiant point of meteor showers is fixed. Prepare to be shocked. Ok, ready?

The radiant moves.

This is a little-known fact. It’s surprising because we often see charts showing the location of radiant points with respect to this or that constellation. But those charts are set for the night of the shower’s peak.

You might be asking: Why hasn’t anyone told me this before? We don’t know! Many long-time meteor observers are surprised to hear this. It happens as Earth moves around the sun. A meteor shower radiant typically moves about 1 degree per day eastward, and approximately parallel to the ecliptic. A map showing the radiant shift of the Delta Aquariids meteor shower is below.

Star chart with stars and constellations and a short yellow arrow with dates at beginning, middle, and end.
The drift of the Delta Aquariid radiant from July 20 through August 9. Map via Don Machholz.

Tip: Don’t stare solely at the radiant

People always want to know how they can find meteor shower radiant points in the night sky. But when you watch a meteor shower, you shouldn’t be staring the whole time at the radiant. Most meteors don’t become visible until they’re some distance from the radiant. So when you’re watching a shower, try looking to the side of the radiant – about 45 degrees off – in all directions on the sky’s dome.

Tip: Know your radiant point rising times

However, there is something important to know about meteor shower radiant points. You’ll start seeing more meteors after the radiant rises into your sky. Most (but not all) meteor showers are best after midnight. That’s because their radiant points don’t rise until midnight or after. The rare and infrequent meteors you might see before the radiant rises will be Earth grazers, which start below your horizon and then trace long paths across your sky.

You’ll also see the most meteors when the radiant is highest in your sky. That’s why the Perseids, for example, are best just before dawn. The radiant for the Perseids rises in the middle of the night for everyone around the globe. And, for all of us, the Perseids’ radiant is highest before dawn. Then the meteors are raining down from the top of the sky. Awesome!

So, if you want to watch a meteor shower, find out what time the radiant point for that shower rises. And then determine when it reaches its highest point in the night sky. You’ll see lots more meteors that way!

Starry sky with dozens of thin radial streaks above silhouetted evergreen trees.
View at EarthSky Community Photos. | David Cox captured a Tau Herculid meteor display – all shooting away from the radiant point – in this image. He wrote: “Composite of 25 meteor streaks captured over 68 minutes during the May 31, 2022, Tau Herculid meteor shower. Although the potential meteor storm did not transpire, there were numerous short meteor streaks visible under the dark sky to provide good viewing entertainment.” Thank you, David!

Tip: Watch for loooong meteors, far from the radiant

Here is one more thing. The meteor paths are generally longer the farther you look from the radiant. This is obvious in the image below. The shorter paths are near the radiant. If you see a short flash during a meteor shower, it is just a meteor headed in your direction. But don’t worry, the comet fluff does not make it to the ground.

Plenty of pink and green straight lines (meteors) radiating from same place in a dark, starry sky.
The Perseid meteor shower and its radiant, which is near the center of this photo. The Andromeda galaxy is near the bottom of the image. Image via NASA.

The radiant point and meteor shower names

By the way, meteor shower radiant points are important for another reason. The shower typically takes its name from the constellation containing the radiant point during the time of the shower’s peak. When several meteor showers share the same constellation, then the closest star gets tagged for the name.

Draconids, Lyrids, Eta and Delta Aquariids, Perseids, Leonids, Geminids … You get the idea!

Bottom line: Meteors enter Earth’s atmosphere on parallel paths. So – just as when you stand on a railroad track, you see the tracks converge in the distance – you’ll see meteors appear to come from a single point in the sky: the radiant point!

Read about all the major meteor showers: EarthSky’s meteor shower guide

How high up are meteors when they begin to glow?

Read more: Meteor showers are here! 10 easy tips for watching

The post Radiant point of meteor showers: All you need to know first appeared on EarthSky.



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Meteor showers are here! 10 easy tips for watching

Hooray! It’s meteor time! That’s right, the Delta Aquariid meteor shower starts in late July. The Delta Aquariids ramble across the sky for weeks! Plus, they blend in with the popular Perseid meteor shower in August.

When is the next meteor shower? Click here for EarthSky’s meteor shower guide

So, how can you optimize your chances of seeing a great meteor display? Follow the tips below.

Bright streak in densely starry sky with band of Milky Way across it, and foreground rock formations.
View at EarthSky Community Photos. | Nils Ribi captured this image in Utah on April 17, 2023, and wrote: “I was setting up to photograph the Milky Way over the Windows Section of Arches National Park in the very early morning hours of April 17, 2023. I noticed a couple of Lyrid meteors in the northeast sky. I set the camera up in that direction and was able to capture a couple of photos. This is the best one. I then proceeded to get a nice pano photo of the Milky Way over the North Window. Life is good!” Thank you, Nils! Check out our tips below for watching meteor showers.

1. Know the peak time

Generally, meteor showers happen over many days as Earth encounters a wide stream of icy particles in space. These particles are debris left behind by a comet. So the peak is a point in time when Earth is expected to encounter the greatest number of comet particles. To find the peak dates of meteor showers, try EarthSky’s meteor guide.

And here’s the catch … the peak of the shower comes at the same time for all of us on Earth. Meanwhile, our clocks are saying different times. You’ll often need to adjust from UTC to your local time.

However, the predictions are not always right on the money. And remember … it’s possible to see nice meteor displays in the hours – even days – before or after the predicted peak.

Just remember, meteor showers are part of nature. So naturally, they often defy prediction.

2. Location, location, location

We can’t say this strongly enough. It’s important to have a dark place to observe in the country. Visit EarthSky’s Best Places to Stargaze.

And … you need a wide-open view of the sky. A farmer’s field? Maybe a stretch of country road? Or a campsite with a clear view in one or more directions? That’s because an open sky will increase your chances of seeing some meteors.

3. Oh no! The moon is out

During a meteor shower, a bright moon is not your friend. In fact, nothing dampens the display of a meteor shower more effectively than a bright moon.

If the moon is out, look at areas of the sky away from the moon. Anything in the moon’s vicinity – including meteors – will likely be washed out by its bright light. And, another tip for watching in moonlight: place some object between yourself and the moon. Observing from the shadow of a barn, or vehicle, even a tree, can help you see more meteors. Basically, place yourself somewhere in the moon’s shadow.

4. Know the expected rate

Here we touch on a topic that sometimes leads to some disappointment, especially among novice meteor-watchers: the rate.

Tables of meteor showers almost always list what is known as the zenithal hourly rate (ZHR) for each shower.

So the ZHR is the number of meteors you’ll see if you’re watching in a very dark sky, with the radiant overhead, when the shower is at its peak. In other words, the ZHR represents the number of meteors you might see per hour given the very best observing conditions during the shower’s maximum.

If the peak occurs when it’s still daylight at your location, if most of the meteors are predominantly faint, if a bright moon is out or if you’re located in a light-polluted area, the total number of meteors you see will be considerably reduced.

5. Don’t worry too much about radiant points

You don’t need to stare all night in a single direction – or even locate the radiant point – to have fun watching the shower. The meteors will appear all over the sky.

But … although you can see meteors shoot up from the horizon before a shower’s radiant rises, you’ll see more meteors after it rises. And you’ll see the most when the radiant is highest in the sky. So, find out the radiant point’s rising time. Then you can pinpoint the best time of night to watch the shower.

And … the radiant point is interesting. If you track meteors backward on the sky’s dome, you’ll find them streaming from their radiant point, a single point within a given constellation. Hence the meteor shower’s name.

6. Watch for an hour or more

Meteor showers will be better if you let your eyes adapt to the dark. That can take as long as 20 minutes. Plus, the meteors tend to come in spurts, followed by lulls. Be patient! You’ll see some.

7. Notice the meteors’ speeds and colors

The Delta Aquarid and Perseid meteors are medium speed meteors. The Leonids are the swiftest meteors and the Taurids are the slowest meteors. The nice thing about a slow and medium speed meteor shower – such as the Perseids – is if you see one and yell “meteor,” other people can catch it as well.

Plus, the August Perseids can be colorful, unlike another beloved shower, the December Geminids. The Geminids tend to be bright and white.

8. Watch for meteor trains

A meteor train is a persistent glow in the air left by some meteors after they have faded from view. Trains are from luminous ionized matter left in the wake of this incoming space debris. About 10% of the Delta Aquariid meteors leave a persistent train.

9. Bring a blanket, a buddy, a hot drink and a lawn chair

A reclining lawn chair helps you lie back in comfort for an hour or more of meteor-watching.

If several of you are watching, take different parts of the sky. If you see one, shout “Meteor!” Dress warmly; the nights can be cool or cold, even during the summer months. You’ll probably appreciate that blanket and warm drink in the wee hours of the morning. Also, leave your laptops and tablets home; even using the nighttime dark mode will ruin your night vision. And this will be tough on some people: leave your cell phone in your pocket or the car. It can also ruin your night vision.

10. Enjoy nature

Relax and enjoy the night sky. Not every meteor shower is a winner. Sometimes, you may come away from a shower seeing only one meteor. But if that one meteor is bright, and takes a slow path across a starry night sky … it’ll be worth it.

To be successful at observing any meteor shower, you need to get into a kind of zen state, waiting and expecting the meteors to come to you, if you place yourself in a good position (country location, wide open sky) to see them.

Or forget the zen state, and let yourself be guided by this old meteor watcher’s motto:

You might see a lot or you might not see many, but if you stay in the house, you won’t see any.

Photos of meteors from EarthSky’s community

Fuzzy, glowing band of the Milky Way over a hill, with a short bright streak near it.
View at EarthSky Community Photos. | Jeremy Evans of California captured a Lyrid meteor zipping along the Milky way on April 22, 2025. Jeremy wrote: “Lyrids Meteor Shower, April 22nd at peak activity. It was a quiet shower this year. I had my camera going all night and only caught one meteor. This single frame is from an all-night 1,200 frame time lapse on my front deck, I’m very fortunate to live under dark Bortle 2 skies. The glow on the horizon is from the last quarter moon just before rising. This meteor also left smoke trails.” Thank you, Jeremy.
Bright, long streak in a dark sky, thin at the ends and thicker in the brilliantly glowing middle.
View at EarthSky Community Photos. | Victor Rogus captured this image on January 3, 2025, in Sedona, Arizona, and wrote: “A very bright meteor, a bolide, struck just before dawn this morning. Our Oculus camera caught the strike. This may have been a Quadrantid meteor; that shower peaks tonight. I froze one night in the backwoods of Missouri to capture my one and only Quadrantid. So this one made my day!” Thank you, Victor!

More meteor photos

Many short streaks in a mostly dark sky. One has a bright explosion at its end.
View at EarthSky Community Photos. | Tameem Altameemi of United Arab Emirates submitted this photo on December 14, 2024, and wrote: “My brother and I decided to go to an area away from light pollution between the mountains in UAE, and despite the moonlight that filled the place, we were able to see and photograph many meteors and fireballs. A special and completely clear night.” Thank you, Tameem!
Dark sky with stars, the Big Dipper and long, thin green glowing streak.
View at EarthSky Community Photos. | Some of the stars of the Big Dipper are part of an open cluster called the Ursa Major Moving Group. Susan Jensen captured this image on September 6, 2024, and wrote: “Right place, right time! Standing on a gravel road in the middle of nowhere, looking across a stubble field. This slow-moving, vibrant meteor stopped me in my tracks! I was shooting the Big Dipper with the shutter locked to catch multiple frames for stacking when this monster did a slow flyby. How lucky that I was able to capture it!” Thank you, Susan!

Bottom line: Meteor showers are unpredictable but always a fun and relaxing time. Maximize your viewing with these tips.

Post your own photos at EarthSky Community Photos

When is the next meteor shower? Click here for EarthSky’s meteor shower guide

The post Meteor showers are here! 10 easy tips for watching first appeared on EarthSky.



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Hooray! It’s meteor time! That’s right, the Delta Aquariid meteor shower starts in late July. The Delta Aquariids ramble across the sky for weeks! Plus, they blend in with the popular Perseid meteor shower in August.

When is the next meteor shower? Click here for EarthSky’s meteor shower guide

So, how can you optimize your chances of seeing a great meteor display? Follow the tips below.

Bright streak in densely starry sky with band of Milky Way across it, and foreground rock formations.
View at EarthSky Community Photos. | Nils Ribi captured this image in Utah on April 17, 2023, and wrote: “I was setting up to photograph the Milky Way over the Windows Section of Arches National Park in the very early morning hours of April 17, 2023. I noticed a couple of Lyrid meteors in the northeast sky. I set the camera up in that direction and was able to capture a couple of photos. This is the best one. I then proceeded to get a nice pano photo of the Milky Way over the North Window. Life is good!” Thank you, Nils! Check out our tips below for watching meteor showers.

1. Know the peak time

Generally, meteor showers happen over many days as Earth encounters a wide stream of icy particles in space. These particles are debris left behind by a comet. So the peak is a point in time when Earth is expected to encounter the greatest number of comet particles. To find the peak dates of meteor showers, try EarthSky’s meteor guide.

And here’s the catch … the peak of the shower comes at the same time for all of us on Earth. Meanwhile, our clocks are saying different times. You’ll often need to adjust from UTC to your local time.

However, the predictions are not always right on the money. And remember … it’s possible to see nice meteor displays in the hours – even days – before or after the predicted peak.

Just remember, meteor showers are part of nature. So naturally, they often defy prediction.

2. Location, location, location

We can’t say this strongly enough. It’s important to have a dark place to observe in the country. Visit EarthSky’s Best Places to Stargaze.

And … you need a wide-open view of the sky. A farmer’s field? Maybe a stretch of country road? Or a campsite with a clear view in one or more directions? That’s because an open sky will increase your chances of seeing some meteors.

3. Oh no! The moon is out

During a meteor shower, a bright moon is not your friend. In fact, nothing dampens the display of a meteor shower more effectively than a bright moon.

If the moon is out, look at areas of the sky away from the moon. Anything in the moon’s vicinity – including meteors – will likely be washed out by its bright light. And, another tip for watching in moonlight: place some object between yourself and the moon. Observing from the shadow of a barn, or vehicle, even a tree, can help you see more meteors. Basically, place yourself somewhere in the moon’s shadow.

4. Know the expected rate

Here we touch on a topic that sometimes leads to some disappointment, especially among novice meteor-watchers: the rate.

Tables of meteor showers almost always list what is known as the zenithal hourly rate (ZHR) for each shower.

So the ZHR is the number of meteors you’ll see if you’re watching in a very dark sky, with the radiant overhead, when the shower is at its peak. In other words, the ZHR represents the number of meteors you might see per hour given the very best observing conditions during the shower’s maximum.

If the peak occurs when it’s still daylight at your location, if most of the meteors are predominantly faint, if a bright moon is out or if you’re located in a light-polluted area, the total number of meteors you see will be considerably reduced.

5. Don’t worry too much about radiant points

You don’t need to stare all night in a single direction – or even locate the radiant point – to have fun watching the shower. The meteors will appear all over the sky.

But … although you can see meteors shoot up from the horizon before a shower’s radiant rises, you’ll see more meteors after it rises. And you’ll see the most when the radiant is highest in the sky. So, find out the radiant point’s rising time. Then you can pinpoint the best time of night to watch the shower.

And … the radiant point is interesting. If you track meteors backward on the sky’s dome, you’ll find them streaming from their radiant point, a single point within a given constellation. Hence the meteor shower’s name.

6. Watch for an hour or more

Meteor showers will be better if you let your eyes adapt to the dark. That can take as long as 20 minutes. Plus, the meteors tend to come in spurts, followed by lulls. Be patient! You’ll see some.

7. Notice the meteors’ speeds and colors

The Delta Aquarid and Perseid meteors are medium speed meteors. The Leonids are the swiftest meteors and the Taurids are the slowest meteors. The nice thing about a slow and medium speed meteor shower – such as the Perseids – is if you see one and yell “meteor,” other people can catch it as well.

Plus, the August Perseids can be colorful, unlike another beloved shower, the December Geminids. The Geminids tend to be bright and white.

8. Watch for meteor trains

A meteor train is a persistent glow in the air left by some meteors after they have faded from view. Trains are from luminous ionized matter left in the wake of this incoming space debris. About 10% of the Delta Aquariid meteors leave a persistent train.

9. Bring a blanket, a buddy, a hot drink and a lawn chair

A reclining lawn chair helps you lie back in comfort for an hour or more of meteor-watching.

If several of you are watching, take different parts of the sky. If you see one, shout “Meteor!” Dress warmly; the nights can be cool or cold, even during the summer months. You’ll probably appreciate that blanket and warm drink in the wee hours of the morning. Also, leave your laptops and tablets home; even using the nighttime dark mode will ruin your night vision. And this will be tough on some people: leave your cell phone in your pocket or the car. It can also ruin your night vision.

10. Enjoy nature

Relax and enjoy the night sky. Not every meteor shower is a winner. Sometimes, you may come away from a shower seeing only one meteor. But if that one meteor is bright, and takes a slow path across a starry night sky … it’ll be worth it.

To be successful at observing any meteor shower, you need to get into a kind of zen state, waiting and expecting the meteors to come to you, if you place yourself in a good position (country location, wide open sky) to see them.

Or forget the zen state, and let yourself be guided by this old meteor watcher’s motto:

You might see a lot or you might not see many, but if you stay in the house, you won’t see any.

Photos of meteors from EarthSky’s community

Fuzzy, glowing band of the Milky Way over a hill, with a short bright streak near it.
View at EarthSky Community Photos. | Jeremy Evans of California captured a Lyrid meteor zipping along the Milky way on April 22, 2025. Jeremy wrote: “Lyrids Meteor Shower, April 22nd at peak activity. It was a quiet shower this year. I had my camera going all night and only caught one meteor. This single frame is from an all-night 1,200 frame time lapse on my front deck, I’m very fortunate to live under dark Bortle 2 skies. The glow on the horizon is from the last quarter moon just before rising. This meteor also left smoke trails.” Thank you, Jeremy.
Bright, long streak in a dark sky, thin at the ends and thicker in the brilliantly glowing middle.
View at EarthSky Community Photos. | Victor Rogus captured this image on January 3, 2025, in Sedona, Arizona, and wrote: “A very bright meteor, a bolide, struck just before dawn this morning. Our Oculus camera caught the strike. This may have been a Quadrantid meteor; that shower peaks tonight. I froze one night in the backwoods of Missouri to capture my one and only Quadrantid. So this one made my day!” Thank you, Victor!

More meteor photos

Many short streaks in a mostly dark sky. One has a bright explosion at its end.
View at EarthSky Community Photos. | Tameem Altameemi of United Arab Emirates submitted this photo on December 14, 2024, and wrote: “My brother and I decided to go to an area away from light pollution between the mountains in UAE, and despite the moonlight that filled the place, we were able to see and photograph many meteors and fireballs. A special and completely clear night.” Thank you, Tameem!
Dark sky with stars, the Big Dipper and long, thin green glowing streak.
View at EarthSky Community Photos. | Some of the stars of the Big Dipper are part of an open cluster called the Ursa Major Moving Group. Susan Jensen captured this image on September 6, 2024, and wrote: “Right place, right time! Standing on a gravel road in the middle of nowhere, looking across a stubble field. This slow-moving, vibrant meteor stopped me in my tracks! I was shooting the Big Dipper with the shutter locked to catch multiple frames for stacking when this monster did a slow flyby. How lucky that I was able to capture it!” Thank you, Susan!

Bottom line: Meteor showers are unpredictable but always a fun and relaxing time. Maximize your viewing with these tips.

Post your own photos at EarthSky Community Photos

When is the next meteor shower? Click here for EarthSky’s meteor shower guide

The post Meteor showers are here! 10 easy tips for watching first appeared on EarthSky.



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‘Unicorn’ long-period radio transient baffles scientists

Artist's impression of the long-period radio transient: a fuzzy bright orange star fills the bottom left, in orbit around a bright white ball, which is surrounded by a flat disk of swirling yellow.
Artist’s impression of the long-period radio transient CHIME J1634+44, which has properties so strange it’s been described as a “unicorn” object. Image via NSF/ AUI/ NSF NRAO/ P.Vosteen.

The National Radio Astronomy Observatory published this original post on July 17, 2025. Edits by EarthSky.

Spinning ‘unicorn’ long-period radio transient defies astrophysics

Using some of the world’s most advanced radio telescopes, astronomers have discovered a bizarre, theory-defying object. Named CHIME J1634+44, it’s what scientists call a long-period radio transient: a source of radio emissions that repeat at long intervals, from minutes to hours. And, strangely, the signals from this long-period radio transient are speeding up. That’s a phenomenon never seen before in this class of astronomical objects.

Plus, the radio waves from CHIME J1634+44 are 100% circularly polarized, meaning they twist in a perfect spiral as they travel. That makes this object one of the most polarized long-period radio transients ever discovered. CHIME J1634+44’s unique properties challenge the current scientific understanding of how these objects work, and raise new questions about what they can teach us about the universe.

A cosmic ‘unicorn’

In light of this object’s strange properties, study lead Fengqiu Adam Dong said:

You could call CHIME J1634+44 a ‘unicorn’, even among other long-period radio transients.

Despite hundreds of detections across multiple observatories, the timing of the repeating radio bursts from CHIME J1634+44 is unclear. Dong said:

The bursts seem to repeat either every 14 minutes, or 841 seconds. But there is a distinct secondary period of 4206 seconds, or 70 minutes, which is exactly five times longer. We think both are real, and this is likely a system with something orbiting a neutron star.

Is this long-period radio transient 1 object or 2?

Normally, objects like neutron stars or white dwarfs slow down over time because they lose energy, so their spin period (time to complete a rotation) gets longer. But for CHIME J1634+44, the spin period is actually getting shorter, meaning its rotation is speeding up.

The only way to make the timing of the bursts fit together is to assume this speeding up is real. But, the researchers say, that’s unlikely if this is a lone star. Therefore, they believe that CHIME J1634+44 might actually be two stars orbiting each other very closely.

If the orbit of this binary system is shrinking – perhaps because they are losing energy by emitting gravitational waves or interacting with each other – it could make it look like the spin period is getting shorter. This kind of shrinking orbit has been seen in other close pairs of white dwarfs.

So is CHIME J1634+44 a pair of white dwarfs, or even a pair of neutron stars? If so, it’s acting unlike any of these objects we’ve studied before. The radio bursts from CHIME J1634+44 are 100% circularly polarized, meaning the radio waves twist in a perfect spiral as they travel. This is extremely rare, and no known white dwarf or neutron star has ever been seen to do this for every burst. The way these radio waves are being produced appears to be different from what we’ve seen in any other known object.

Dong said:

The discovery of CHIME J1634+44 expands the known population of long-period radio transients and challenges existing models of neutron stars and white dwarfs, suggesting there may be many more such objects awaiting discovery.

A collaborative success

The unparalleled collection of telescopes used in this research allowed scientists to detect and study the object’s unusual signals in detail.

The Canadian Hydrogen Intensity Mapping Experiment’s (CHIME) wide field of view and daily sky scans detected the transient’s periodic bursts and monitored its spin evolution.

The National Science Foundation’s Very Large Array (VLA), supported by realfast (a system for real-time fast transient searches), provided high-frequency follow-up observations to mitigate interstellar medium distortions and refine localization.

The National Science Foundation’s Green Bank Telescope (GBT) contributed sensitive, high-resolution timing data to analyze polarization and spin-up behavior, enhancing precision for gravitational wave studies.

NASA’s Neil Gehrels Swift Observatory searched for X-ray counterparts, and its multi-wavelength capabilities allowed the researchers to probe for high-energy signals that complemented radio observations.

Bottom line: Astronomers have discovered a long-period radio transient with bizarre, theory-defying properties. It’s incredibly polarized, and its spin appears to be speeding up.

Via NRAO

Read more: Unusual star pulsing in X-ray and radio baffles scientists

The post ‘Unicorn’ long-period radio transient baffles scientists first appeared on EarthSky.



from EarthSky https://ift.tt/EWVxt1p
Artist's impression of the long-period radio transient: a fuzzy bright orange star fills the bottom left, in orbit around a bright white ball, which is surrounded by a flat disk of swirling yellow.
Artist’s impression of the long-period radio transient CHIME J1634+44, which has properties so strange it’s been described as a “unicorn” object. Image via NSF/ AUI/ NSF NRAO/ P.Vosteen.

The National Radio Astronomy Observatory published this original post on July 17, 2025. Edits by EarthSky.

Spinning ‘unicorn’ long-period radio transient defies astrophysics

Using some of the world’s most advanced radio telescopes, astronomers have discovered a bizarre, theory-defying object. Named CHIME J1634+44, it’s what scientists call a long-period radio transient: a source of radio emissions that repeat at long intervals, from minutes to hours. And, strangely, the signals from this long-period radio transient are speeding up. That’s a phenomenon never seen before in this class of astronomical objects.

Plus, the radio waves from CHIME J1634+44 are 100% circularly polarized, meaning they twist in a perfect spiral as they travel. That makes this object one of the most polarized long-period radio transients ever discovered. CHIME J1634+44’s unique properties challenge the current scientific understanding of how these objects work, and raise new questions about what they can teach us about the universe.

A cosmic ‘unicorn’

In light of this object’s strange properties, study lead Fengqiu Adam Dong said:

You could call CHIME J1634+44 a ‘unicorn’, even among other long-period radio transients.

Despite hundreds of detections across multiple observatories, the timing of the repeating radio bursts from CHIME J1634+44 is unclear. Dong said:

The bursts seem to repeat either every 14 minutes, or 841 seconds. But there is a distinct secondary period of 4206 seconds, or 70 minutes, which is exactly five times longer. We think both are real, and this is likely a system with something orbiting a neutron star.

Is this long-period radio transient 1 object or 2?

Normally, objects like neutron stars or white dwarfs slow down over time because they lose energy, so their spin period (time to complete a rotation) gets longer. But for CHIME J1634+44, the spin period is actually getting shorter, meaning its rotation is speeding up.

The only way to make the timing of the bursts fit together is to assume this speeding up is real. But, the researchers say, that’s unlikely if this is a lone star. Therefore, they believe that CHIME J1634+44 might actually be two stars orbiting each other very closely.

If the orbit of this binary system is shrinking – perhaps because they are losing energy by emitting gravitational waves or interacting with each other – it could make it look like the spin period is getting shorter. This kind of shrinking orbit has been seen in other close pairs of white dwarfs.

So is CHIME J1634+44 a pair of white dwarfs, or even a pair of neutron stars? If so, it’s acting unlike any of these objects we’ve studied before. The radio bursts from CHIME J1634+44 are 100% circularly polarized, meaning the radio waves twist in a perfect spiral as they travel. This is extremely rare, and no known white dwarf or neutron star has ever been seen to do this for every burst. The way these radio waves are being produced appears to be different from what we’ve seen in any other known object.

Dong said:

The discovery of CHIME J1634+44 expands the known population of long-period radio transients and challenges existing models of neutron stars and white dwarfs, suggesting there may be many more such objects awaiting discovery.

A collaborative success

The unparalleled collection of telescopes used in this research allowed scientists to detect and study the object’s unusual signals in detail.

The Canadian Hydrogen Intensity Mapping Experiment’s (CHIME) wide field of view and daily sky scans detected the transient’s periodic bursts and monitored its spin evolution.

The National Science Foundation’s Very Large Array (VLA), supported by realfast (a system for real-time fast transient searches), provided high-frequency follow-up observations to mitigate interstellar medium distortions and refine localization.

The National Science Foundation’s Green Bank Telescope (GBT) contributed sensitive, high-resolution timing data to analyze polarization and spin-up behavior, enhancing precision for gravitational wave studies.

NASA’s Neil Gehrels Swift Observatory searched for X-ray counterparts, and its multi-wavelength capabilities allowed the researchers to probe for high-energy signals that complemented radio observations.

Bottom line: Astronomers have discovered a long-period radio transient with bizarre, theory-defying properties. It’s incredibly polarized, and its spin appears to be speeding up.

Via NRAO

Read more: Unusual star pulsing in X-ray and radio baffles scientists

The post ‘Unicorn’ long-period radio transient baffles scientists first appeared on EarthSky.



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Can sharks smile? It’s Shark Week! Enjoy these shark videos

It’s shark week! It started on July 20 and will end on July 26, 2025. We have some shark videos for you to celebrate it:


Wrangling A Predator: Science and Community Protecting Tiger Sharks


What Happened When 2 Shark Species Shared a Feast?

Can sharks smile?

Many animals show feelings. We’ve all seen examples of animals showing happiness, anger or fear. And dogs, monkeys and dolphins, for example, all show expressions akin to human smiles. But sharks? Sharks do sometimes look as if they’re smiling. They’re often portrayed in books and movies as smiling. But scientists say it’s not likely sharks can or do smile. Unlike dogs, monkeys and dolphins, sharks are fish. And, in sharks and other fish, the parts of the brain related to feelings aren’t developed enough to produce a smile, according to scientists.

Yet sharks do communicate, by twisting their bodies into certain positions. And they act differently from day to day, depending on how much food they’ve eaten or how cold the water is. Scientists call those things behaviors, not emotions.

And even though a shark’s body is made of flexible cartilage, its jaws are rigid and calcified. A strong jaw lets a shark pulverize its food. But the same rigidity makes a true shark smile impossible.

Did you see the Disney film Finding Nemo? Then you know Bruce, who is almost always smiling and whose refrain is: “I am a nice shark, not a mindless eating machine. If I am to change this image, I must first change myself. Fish are friends, not food.” Cute, but not science!

Smiles are a form of communication

Smiling seems to be instinctual in people as a basic form of communication. When someone smiles, we usually read the smile as happiness. Likewise, in humans, a frown signals sadness or possibly anger.

And scientists can’t possibly know everything. Maybe we just don’t understand how to read the emotions of a fish. Marine biologist Steven Webster, now retired from Monterey Bay Aquarium and currently head of Sea Studios Foundation, once told EarthSky:

We don’t know if fish or turtles have emotions. And we’ll never know. It could be that sharks are out there chuckling and writing poetry every day, and they just don’t share it with us.

But for now, as far as scientists understand it, sharks and other fish aren’t capable of smiling. That’s despite the fact that some really look as if they’re smiling.

Do sharks smile: Two dolphins with heads poking up above water and upturned open mouths.
Dolphins always look happy. Can they smile? Maybe they can, as they are mammals. But according to scientists, sharks, as they are fish, they probably don’t have that capability. Yet they can communicate in their own ways. Image via Pexels/ Hamid Elbaz.

What do scientists say?

So, according to scientists, it’s not likely that sharks can smile. And scientists warn against reading too much into animal faces and behaviors. That sort of anthropomorphizing – attributing human form or behavior to animals – can get in the way of scientific objectivity.

Still, future scientists are sure to discover more about sharks’ relationship with their world, giving us all a better glimpse into the lives of the creatures who co-inhabit planet Earth with us.

Of course many other animals – including our beloved pets – appear to smile.

Bottom line: Can sharks smile? Not likely. But dogs, monkeys and dolphins all show expressions akin to human smiles. Learn more about sharks during Shark Week.

Shark Week on the Discovery channel starts on July 20, 2025. Click in for info

Read more: Sharkcano, an undersea volcano where sharks live

The post Can sharks smile? It’s Shark Week! Enjoy these shark videos first appeared on EarthSky.



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It’s shark week! It started on July 20 and will end on July 26, 2025. We have some shark videos for you to celebrate it:


Wrangling A Predator: Science and Community Protecting Tiger Sharks


What Happened When 2 Shark Species Shared a Feast?

Can sharks smile?

Many animals show feelings. We’ve all seen examples of animals showing happiness, anger or fear. And dogs, monkeys and dolphins, for example, all show expressions akin to human smiles. But sharks? Sharks do sometimes look as if they’re smiling. They’re often portrayed in books and movies as smiling. But scientists say it’s not likely sharks can or do smile. Unlike dogs, monkeys and dolphins, sharks are fish. And, in sharks and other fish, the parts of the brain related to feelings aren’t developed enough to produce a smile, according to scientists.

Yet sharks do communicate, by twisting their bodies into certain positions. And they act differently from day to day, depending on how much food they’ve eaten or how cold the water is. Scientists call those things behaviors, not emotions.

And even though a shark’s body is made of flexible cartilage, its jaws are rigid and calcified. A strong jaw lets a shark pulverize its food. But the same rigidity makes a true shark smile impossible.

Did you see the Disney film Finding Nemo? Then you know Bruce, who is almost always smiling and whose refrain is: “I am a nice shark, not a mindless eating machine. If I am to change this image, I must first change myself. Fish are friends, not food.” Cute, but not science!

Smiles are a form of communication

Smiling seems to be instinctual in people as a basic form of communication. When someone smiles, we usually read the smile as happiness. Likewise, in humans, a frown signals sadness or possibly anger.

And scientists can’t possibly know everything. Maybe we just don’t understand how to read the emotions of a fish. Marine biologist Steven Webster, now retired from Monterey Bay Aquarium and currently head of Sea Studios Foundation, once told EarthSky:

We don’t know if fish or turtles have emotions. And we’ll never know. It could be that sharks are out there chuckling and writing poetry every day, and they just don’t share it with us.

But for now, as far as scientists understand it, sharks and other fish aren’t capable of smiling. That’s despite the fact that some really look as if they’re smiling.

Do sharks smile: Two dolphins with heads poking up above water and upturned open mouths.
Dolphins always look happy. Can they smile? Maybe they can, as they are mammals. But according to scientists, sharks, as they are fish, they probably don’t have that capability. Yet they can communicate in their own ways. Image via Pexels/ Hamid Elbaz.

What do scientists say?

So, according to scientists, it’s not likely that sharks can smile. And scientists warn against reading too much into animal faces and behaviors. That sort of anthropomorphizing – attributing human form or behavior to animals – can get in the way of scientific objectivity.

Still, future scientists are sure to discover more about sharks’ relationship with their world, giving us all a better glimpse into the lives of the creatures who co-inhabit planet Earth with us.

Of course many other animals – including our beloved pets – appear to smile.

Bottom line: Can sharks smile? Not likely. But dogs, monkeys and dolphins all show expressions akin to human smiles. Learn more about sharks during Shark Week.

Shark Week on the Discovery channel starts on July 20, 2025. Click in for info

Read more: Sharkcano, an undersea volcano where sharks live

The post Can sharks smile? It’s Shark Week! Enjoy these shark videos first appeared on EarthSky.



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Summer Triangle star: Altair is variable and spins fast!

Star chart showing a purple triangle with 3 stars, including Altair and its constellation Aquila.
Altair, in the constellation Aquila the Eagle, makes up the Summer Triangle along with Deneb and Vega. You’ll find this large triangle in the east in the evening in July. As the months pass, the Triangle will shift westward. It’ll grace our skies until around the year’s end. Chart via EarthSky.

The bright star Altair, aka Alpha Aquilae, shines as the brightest star in the constellation Aquila the Eagle. Mostly known for being one of the three Summer Triangle stars, this star is distinctive in its own right. It shines at magnitude +0.76. It’s only 16.8 light-years away from Earth, making it one of our nearest stellar neighbors. Plus, it has two more noteworthy features.

First, Altair rotates rapidly

This star requires only about 10 hours to spin once on its axis. That’s in contrast to 24 hours for our Earth to spin once, and about 27 days for our sun. In other words, this mighty star spins on its axis more rapidly than Earth! So this speedy spin tends to flatten the star a bit, much as a pizza crust flattens as it spins. Rough estimates are that Altair’s flattening is about 14%. Also, our sun is an oblate spheroid, although its flattening is difficult to measure due to the low rotation rate.

In 2007, University of Michigan astronomers combined light from four widely separated telescopes to produce the first picture (below) showing surface details on Altair. The researchers, led by John Monnier, used optical interferometry to get this image. Read more about the study at SpaceDaily.com.

Second, it’s variable … but not in a usual way

Variable stars brighten and dim, many on a (more or less) regular schedule. But Altair has as many as nine different rates of brightenings and dimmings. You won’t see these brightness variations with your eye. They’re too small to measure without sensitive instruments. But they’re there, and they’re likely related to Altair’s fast rotation.

By the way, if Altair took the place of our sun, at the distance the sun is now, life on Earth would be doomed. That’s because Altair is over 10 times more luminous that our sun. As you might have guessed, Altair is a more massive star than our sun, with about 1.8 times the sun’s mass. Its diameter is estimated to be between 1.6 to 2 times that of the sun. And its surface temperature is between 11,960 degrees F (6,626 C) to 14,840 F (8,226 C).

Altair is a white main sequence star – with a spectral type A7 – and is the 12th brightest star in the sky. It shares that spot with the star Acrux in the constellation Crux.

The star is classified as a Delta Scuti variable star since it shows slight changes in luminosity. It has three dim companion stars visible through telescopes. And not only it is a fast spinner, it moves quickly in front of its background stars. In fact, it’ll move about a full degree over the next 5,000 years.

How to see Altair

Altair has an apparent magnitude of +0.76. So you can see Altair easily with the eye.

But how will you recognize it? If you’re outside on a July or August evening, watch for the large Summer Triangle asterism in the east (as shown on the chart at the top). Look near the horizon for Altair, the last of the three Summer Triangle stars to ascend over your horizon.

You will recognize Altair by the two fainter stars on either side of it.

Also, the Great Rift of the summer Milky Way passes through the Summer Triangle. In fact, it goes right between the stars Vega and Altair. In dark skies in June, July and August, you can see rich star fields with your binoculars on both sides of the Great Rift.

‘Forbidden Planet’

In modern western culture, Altair is probably best known for being the home star system of the aliens in the 1956 science fiction film Forbidden Planet.

Altair in history and myth

The name Altair is Arabic in origin and has the same meaning as the name of the constellation Aquila in Latin; that is, they both mean simply “eagle.”

In classical mythology Aquila, and by extension Altair as well, was an eagle favored by Zeus. He played a part in numerous myths, including the abduction of Ganymede in which Aquila carries off a young boy (Ganymede) to Mount Olympus on Zeus’ command to become the cupbearer to the gods. In another myth Aquila is the eagle that torments Prometheus, until Hercules shoots it with poisoned arrows.

In India, Altair with its two flanking stars, Beta and Gamma (Tarazed and Alshain), in tradition represent the celestial footprints of the god Vishnu.

Altair is separated from the similar looking (but brighter) star Vega in the constellation Lyra the Harp by the great starlit band of the Milky Way. In Asia, this hazy band across our sky is known as the Celestial River. One story common in China, Japan and Korea is of a young herdsman (Altair) who falls in love with a celestial princess (Vega), who weaves the fabric of heaven.

The princess became so enamored of the herdsman that she neglects her weaving duties. This act enrages the princess’s father, the Celestial Emperor, who decrees that the herdsman must stay away from his daughter, on the opposite side of the River. The Emperor finally listened to the princess’s pleas, however, and allowed the herdsman to cross the Celestial River once per year, on the seventh day of the seventh month.

In Japan, Altair is Hikoboshi, and Vega is Orihime (or Tanabata). If it rains on the day of the festival of Tanabata, the rain represents Orihime’s tears shed because Hikoboshi could not navigate the treacherous waters of the Celestial River.

Altair’s position

The position of Altair is RA: 19h 50m 47.0s, dec: +08° 52′ 06″

Antique colored etching of flying eagle and other figures including an ugly fish, all scattered with stars.
Altair of Aquila the Eagle, with 2 smaller constellations nearby. Image via Wikipedia (public domain).

Bottom line: Altair is the brightest star in the constellation Aquila the Eagle, and one of the closest stars to our solar system. Although 1.8 times our sun’s mass, it spins on its axis in only about 10 hours.

Our Summer Triangle series includes:

Vega is bright and blue-white

Deneb is distant and very luminous

Altair spins fast!

The post Summer Triangle star: Altair is variable and spins fast! first appeared on EarthSky.



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Star chart showing a purple triangle with 3 stars, including Altair and its constellation Aquila.
Altair, in the constellation Aquila the Eagle, makes up the Summer Triangle along with Deneb and Vega. You’ll find this large triangle in the east in the evening in July. As the months pass, the Triangle will shift westward. It’ll grace our skies until around the year’s end. Chart via EarthSky.

The bright star Altair, aka Alpha Aquilae, shines as the brightest star in the constellation Aquila the Eagle. Mostly known for being one of the three Summer Triangle stars, this star is distinctive in its own right. It shines at magnitude +0.76. It’s only 16.8 light-years away from Earth, making it one of our nearest stellar neighbors. Plus, it has two more noteworthy features.

First, Altair rotates rapidly

This star requires only about 10 hours to spin once on its axis. That’s in contrast to 24 hours for our Earth to spin once, and about 27 days for our sun. In other words, this mighty star spins on its axis more rapidly than Earth! So this speedy spin tends to flatten the star a bit, much as a pizza crust flattens as it spins. Rough estimates are that Altair’s flattening is about 14%. Also, our sun is an oblate spheroid, although its flattening is difficult to measure due to the low rotation rate.

In 2007, University of Michigan astronomers combined light from four widely separated telescopes to produce the first picture (below) showing surface details on Altair. The researchers, led by John Monnier, used optical interferometry to get this image. Read more about the study at SpaceDaily.com.

Second, it’s variable … but not in a usual way

Variable stars brighten and dim, many on a (more or less) regular schedule. But Altair has as many as nine different rates of brightenings and dimmings. You won’t see these brightness variations with your eye. They’re too small to measure without sensitive instruments. But they’re there, and they’re likely related to Altair’s fast rotation.

By the way, if Altair took the place of our sun, at the distance the sun is now, life on Earth would be doomed. That’s because Altair is over 10 times more luminous that our sun. As you might have guessed, Altair is a more massive star than our sun, with about 1.8 times the sun’s mass. Its diameter is estimated to be between 1.6 to 2 times that of the sun. And its surface temperature is between 11,960 degrees F (6,626 C) to 14,840 F (8,226 C).

Altair is a white main sequence star – with a spectral type A7 – and is the 12th brightest star in the sky. It shares that spot with the star Acrux in the constellation Crux.

The star is classified as a Delta Scuti variable star since it shows slight changes in luminosity. It has three dim companion stars visible through telescopes. And not only it is a fast spinner, it moves quickly in front of its background stars. In fact, it’ll move about a full degree over the next 5,000 years.

How to see Altair

Altair has an apparent magnitude of +0.76. So you can see Altair easily with the eye.

But how will you recognize it? If you’re outside on a July or August evening, watch for the large Summer Triangle asterism in the east (as shown on the chart at the top). Look near the horizon for Altair, the last of the three Summer Triangle stars to ascend over your horizon.

You will recognize Altair by the two fainter stars on either side of it.

Also, the Great Rift of the summer Milky Way passes through the Summer Triangle. In fact, it goes right between the stars Vega and Altair. In dark skies in June, July and August, you can see rich star fields with your binoculars on both sides of the Great Rift.

‘Forbidden Planet’

In modern western culture, Altair is probably best known for being the home star system of the aliens in the 1956 science fiction film Forbidden Planet.

Altair in history and myth

The name Altair is Arabic in origin and has the same meaning as the name of the constellation Aquila in Latin; that is, they both mean simply “eagle.”

In classical mythology Aquila, and by extension Altair as well, was an eagle favored by Zeus. He played a part in numerous myths, including the abduction of Ganymede in which Aquila carries off a young boy (Ganymede) to Mount Olympus on Zeus’ command to become the cupbearer to the gods. In another myth Aquila is the eagle that torments Prometheus, until Hercules shoots it with poisoned arrows.

In India, Altair with its two flanking stars, Beta and Gamma (Tarazed and Alshain), in tradition represent the celestial footprints of the god Vishnu.

Altair is separated from the similar looking (but brighter) star Vega in the constellation Lyra the Harp by the great starlit band of the Milky Way. In Asia, this hazy band across our sky is known as the Celestial River. One story common in China, Japan and Korea is of a young herdsman (Altair) who falls in love with a celestial princess (Vega), who weaves the fabric of heaven.

The princess became so enamored of the herdsman that she neglects her weaving duties. This act enrages the princess’s father, the Celestial Emperor, who decrees that the herdsman must stay away from his daughter, on the opposite side of the River. The Emperor finally listened to the princess’s pleas, however, and allowed the herdsman to cross the Celestial River once per year, on the seventh day of the seventh month.

In Japan, Altair is Hikoboshi, and Vega is Orihime (or Tanabata). If it rains on the day of the festival of Tanabata, the rain represents Orihime’s tears shed because Hikoboshi could not navigate the treacherous waters of the Celestial River.

Altair’s position

The position of Altair is RA: 19h 50m 47.0s, dec: +08° 52′ 06″

Antique colored etching of flying eagle and other figures including an ugly fish, all scattered with stars.
Altair of Aquila the Eagle, with 2 smaller constellations nearby. Image via Wikipedia (public domain).

Bottom line: Altair is the brightest star in the constellation Aquila the Eagle, and one of the closest stars to our solar system. Although 1.8 times our sun’s mass, it spins on its axis in only about 10 hours.

Our Summer Triangle series includes:

Vega is bright and blue-white

Deneb is distant and very luminous

Altair spins fast!

The post Summer Triangle star: Altair is variable and spins fast! first appeared on EarthSky.



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Companion for Betelgeuse confirmed! Beloved red star has a blue-white buddy

Companion for Betelgeuse: Bright reddish circle with white spot in the center, and smaller blue spot next to it on black background.
View larger. | The ‘Alopeke instrument on the Gemini North telescope in Hawaii obtained this image of the companion for Betelgeuse. Here, Betelgeuse is the red object, and the companion is blue. This newly discovered companion appears to lie within the extended outer extended atmosphere of Betelgeuse itself. Image via International Gemini Observatory/ NOIRLab/ NSF/ AURA; Image Processing: M. Zamani (NSF NOIRLab).
  • Betelgeuse is a famous red supergiant star, located some 650-700 light-years from Earth. Its fame stems in part from the fact it’ll someday explode and become visibly brighter in our sky! Astronomers have long thought Betelgeuse might have a smaller, fainter companion star.
  • Betelgeuse does indeed have a buddy, astronomers have now confirmed using the Gemini North telescope in Hawaii. The companion star is blue-white and orbits within Betelgeuse’s outer atmosphere.
  • Both stars likely formed at the same time, only about 10 million years ago. The fate of the companion isn’t entirely known, but it may eventually be consumed by Betelgeuse.

A companion for Betelgeuse

It’s confirmed! The beloved red supergiant star Betelgeuse has a companion! Astronomers using the ‘Alopeke instrument on the Gemini North telescope in Hawaii found the companion star. The researchers said on July 21, 2025 that the companion has an estimated mass of around 1.5 times that of our sun. It appears to be an A- or B-type pre-main-sequence star — a hot, young, blue-white star that has not yet initiated hydrogen burning in its core.

The companion is 6 magnitudes fainter than Betelgeuse and orbits close to Betelgeuse itself, within the supergiant star’s extended outer atmosphere.

So … wow! What an incredible example of stellar evolution in action. Both Betelgeuse and its companion are relatively young stars, only about 10 million years old. Both are massive stars, of the sort that burn their fuel quickly. In accordance with what astronomers have learned about how stars evolve, Betelgeuse started out more massive than its companion. It probably started with about 15 to 20 times the sun’s mass. Betelgeuse has already spent the hydrogen fuel in its core and evolved to the red giant stage. It’ll famously explode as a supernova someday soon, anytime between now and 10,000 years from now.

The companion – at only 1.5 times the sun’s mass – appears to be still forming. It’s not massive enough to become a supernova itself someday, but, in any case, its life will be cut short by Betelgeuse. It may eventually spiral into Betelgeuse.

Several astronomers in recent decades have suggested a companion for Betelgeuse. A previous study from last year strongly suggested it. But now, the new observations have confirmed it.

The researchers published their peer-reviewed findings in The Astrophysical Journal Letters on July 21, 2025.

Bright stars of the constellation Orion, with millions of other stars in the background. A square in the upper left corner contains a bright reddish circle with white spot in the center, and smaller blue spot next to it on black background.
View larger. | Betelgeuse and its companion in the constellation Orion. Image via International Gemini Observatory/ NOIRLab/ NSF/ AURA; Image Processing: M. Zamani (NSF NOIRLab).

Higher-resolution images reveal Betelgeuse’s buddy

Astrophysicist Steve Howell at NASA Ames Research Center in California led the team that made the discovery. The researchers used a speckle imager on Gemini North called ‘Alopeke (‘fox’ in Hawaiian). Speckle imaging uses very short exposure times to freeze out the distortions in astronomical images caused by Earth’s atmosphere. The astronomers combined it with the power of Gemini North’s 8.1-meter mirror to produce higher-resolution images.

The researchers analyzed the light of the fainter companion star to determine its characteristics. It is an A- or B-type pre-main-sequence star: young, hot and blue-white in color, in contrast to Betelegeuse’s fiery red. In addition, it is also much smaller and less massive than Betelgeuse, only 1.5 times as massive as our sun. Betelgeuse itself is enormous, about 1,400 times larger in size than the sun.

Optically, the companion star is 6 magnitudes fainter than Betelgeuse.

The researchers say that both stars likely formed at the same time. The companion, however, will probably have a sorter lifetime. It will eventually be consumed by Betelgeuse after it spirals into the red supergiant.

An impressive accomplishment

The detection of the companion star is an impressive achievement, to be sure. Howell said:

Gemini North’s ability to obtain high angular resolutions and sharp contrasts allowed the companion of Betelgeuse to be directly detected. Papers that predicted Betelgeuse’s companion believed that no one would likely ever be able to image it.

This detection was at the very extremes of what can be accomplished with Gemini in terms of high-angular resolution imaging, and it worked. This now opens the door for other observational pursuits of a similar nature.

Martin Still, the National Science Foundation program director for the International Gemini Observatory, added:

The speckle capabilities provided by the International Gemini Observatory continue to be a spectacular tool, open to all astronomers for a wide range of astronomy applications. Delivering the solution to the Betelgeuse problem that has stood for hundreds of years will stand as an evocative highlight achievement.

Bright red-orange blob with white spot and a bump on it, on black background.
The red supergiant star Betelgeuse is a beloved star, bright and easy to see in the famous constellation Orion the Hunter. See the “bump” on the left side in this submillimeter-wavelength image of the star? It’s hot gas from the red giant star’s extended atmosphere. Image via the ALMA telescope in Chile in 2020/ ESO/ NAOJ/ NRAO)/ E. O’Gorman/ P. Kervella.
Smiling man with white beard, moustache and pony tail, wearing a red jacket.
Steve Howell at NASA’s Ames Research Center led the team that discovered the companion star to Betelgeuse. Image via NASA.

The Great Dimming of Betelgeuse

Betelgeuse is a variable star, but also experiences periods of even more significant dimming in brightness. It most recently did so in 2019-2020 and again in 2024. In fact, these dimming episodes have sparked speculation that Betelgeuse might explode soon (and astronomers say that indeed it will do so one day).

In 2021, scientists said that massive amounts of hot gas and dust was being expelled from Betelgeuse’s atmosphere. This, consequently, caused the dimming, as the dust temporarily blocked some of the star’s light.

Interestingly, the previous study from 2024 also suggested that if Betelgeuse did have a companion, then it probably won’t go boom anytime soon. So we might be waiting a long time yet!

Bottom line: Astronomers using the Gemini North telescope in Hawaii have confirmed a companion for Betelgeuse!

Source: Probable Direct Imaging Discovery of the Stellar Companion to Betelgeuse

Via NOIRLab.

Read more: Betelgeuse will explode someday, but WHEN?

Read more: How far is Betelgeuse, the famous red supergiant star?

The post Companion for Betelgeuse confirmed! Beloved red star has a blue-white buddy first appeared on EarthSky.



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Companion for Betelgeuse: Bright reddish circle with white spot in the center, and smaller blue spot next to it on black background.
View larger. | The ‘Alopeke instrument on the Gemini North telescope in Hawaii obtained this image of the companion for Betelgeuse. Here, Betelgeuse is the red object, and the companion is blue. This newly discovered companion appears to lie within the extended outer extended atmosphere of Betelgeuse itself. Image via International Gemini Observatory/ NOIRLab/ NSF/ AURA; Image Processing: M. Zamani (NSF NOIRLab).
  • Betelgeuse is a famous red supergiant star, located some 650-700 light-years from Earth. Its fame stems in part from the fact it’ll someday explode and become visibly brighter in our sky! Astronomers have long thought Betelgeuse might have a smaller, fainter companion star.
  • Betelgeuse does indeed have a buddy, astronomers have now confirmed using the Gemini North telescope in Hawaii. The companion star is blue-white and orbits within Betelgeuse’s outer atmosphere.
  • Both stars likely formed at the same time, only about 10 million years ago. The fate of the companion isn’t entirely known, but it may eventually be consumed by Betelgeuse.

A companion for Betelgeuse

It’s confirmed! The beloved red supergiant star Betelgeuse has a companion! Astronomers using the ‘Alopeke instrument on the Gemini North telescope in Hawaii found the companion star. The researchers said on July 21, 2025 that the companion has an estimated mass of around 1.5 times that of our sun. It appears to be an A- or B-type pre-main-sequence star — a hot, young, blue-white star that has not yet initiated hydrogen burning in its core.

The companion is 6 magnitudes fainter than Betelgeuse and orbits close to Betelgeuse itself, within the supergiant star’s extended outer atmosphere.

So … wow! What an incredible example of stellar evolution in action. Both Betelgeuse and its companion are relatively young stars, only about 10 million years old. Both are massive stars, of the sort that burn their fuel quickly. In accordance with what astronomers have learned about how stars evolve, Betelgeuse started out more massive than its companion. It probably started with about 15 to 20 times the sun’s mass. Betelgeuse has already spent the hydrogen fuel in its core and evolved to the red giant stage. It’ll famously explode as a supernova someday soon, anytime between now and 10,000 years from now.

The companion – at only 1.5 times the sun’s mass – appears to be still forming. It’s not massive enough to become a supernova itself someday, but, in any case, its life will be cut short by Betelgeuse. It may eventually spiral into Betelgeuse.

Several astronomers in recent decades have suggested a companion for Betelgeuse. A previous study from last year strongly suggested it. But now, the new observations have confirmed it.

The researchers published their peer-reviewed findings in The Astrophysical Journal Letters on July 21, 2025.

Bright stars of the constellation Orion, with millions of other stars in the background. A square in the upper left corner contains a bright reddish circle with white spot in the center, and smaller blue spot next to it on black background.
View larger. | Betelgeuse and its companion in the constellation Orion. Image via International Gemini Observatory/ NOIRLab/ NSF/ AURA; Image Processing: M. Zamani (NSF NOIRLab).

Higher-resolution images reveal Betelgeuse’s buddy

Astrophysicist Steve Howell at NASA Ames Research Center in California led the team that made the discovery. The researchers used a speckle imager on Gemini North called ‘Alopeke (‘fox’ in Hawaiian). Speckle imaging uses very short exposure times to freeze out the distortions in astronomical images caused by Earth’s atmosphere. The astronomers combined it with the power of Gemini North’s 8.1-meter mirror to produce higher-resolution images.

The researchers analyzed the light of the fainter companion star to determine its characteristics. It is an A- or B-type pre-main-sequence star: young, hot and blue-white in color, in contrast to Betelegeuse’s fiery red. In addition, it is also much smaller and less massive than Betelgeuse, only 1.5 times as massive as our sun. Betelgeuse itself is enormous, about 1,400 times larger in size than the sun.

Optically, the companion star is 6 magnitudes fainter than Betelgeuse.

The researchers say that both stars likely formed at the same time. The companion, however, will probably have a sorter lifetime. It will eventually be consumed by Betelgeuse after it spirals into the red supergiant.

An impressive accomplishment

The detection of the companion star is an impressive achievement, to be sure. Howell said:

Gemini North’s ability to obtain high angular resolutions and sharp contrasts allowed the companion of Betelgeuse to be directly detected. Papers that predicted Betelgeuse’s companion believed that no one would likely ever be able to image it.

This detection was at the very extremes of what can be accomplished with Gemini in terms of high-angular resolution imaging, and it worked. This now opens the door for other observational pursuits of a similar nature.

Martin Still, the National Science Foundation program director for the International Gemini Observatory, added:

The speckle capabilities provided by the International Gemini Observatory continue to be a spectacular tool, open to all astronomers for a wide range of astronomy applications. Delivering the solution to the Betelgeuse problem that has stood for hundreds of years will stand as an evocative highlight achievement.

Bright red-orange blob with white spot and a bump on it, on black background.
The red supergiant star Betelgeuse is a beloved star, bright and easy to see in the famous constellation Orion the Hunter. See the “bump” on the left side in this submillimeter-wavelength image of the star? It’s hot gas from the red giant star’s extended atmosphere. Image via the ALMA telescope in Chile in 2020/ ESO/ NAOJ/ NRAO)/ E. O’Gorman/ P. Kervella.
Smiling man with white beard, moustache and pony tail, wearing a red jacket.
Steve Howell at NASA’s Ames Research Center led the team that discovered the companion star to Betelgeuse. Image via NASA.

The Great Dimming of Betelgeuse

Betelgeuse is a variable star, but also experiences periods of even more significant dimming in brightness. It most recently did so in 2019-2020 and again in 2024. In fact, these dimming episodes have sparked speculation that Betelgeuse might explode soon (and astronomers say that indeed it will do so one day).

In 2021, scientists said that massive amounts of hot gas and dust was being expelled from Betelgeuse’s atmosphere. This, consequently, caused the dimming, as the dust temporarily blocked some of the star’s light.

Interestingly, the previous study from 2024 also suggested that if Betelgeuse did have a companion, then it probably won’t go boom anytime soon. So we might be waiting a long time yet!

Bottom line: Astronomers using the Gemini North telescope in Hawaii have confirmed a companion for Betelgeuse!

Source: Probable Direct Imaging Discovery of the Stellar Companion to Betelgeuse

Via NOIRLab.

Read more: Betelgeuse will explode someday, but WHEN?

Read more: How far is Betelgeuse, the famous red supergiant star?

The post Companion for Betelgeuse confirmed! Beloved red star has a blue-white buddy first appeared on EarthSky.



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