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Oldest Mars meteorite reveals Mars lost its water early

Mars meteorite: Smooth, flat gray surface, partly light and partly darker, with dark cracks in it.
View larger. | Closeup of the Teghaza 001 Mars meteorite. A new analysis of this ancient piece of the red planet reveals it was starting to lose its water over 4 billion years ago. Image via NASA.
  • Teghaza 001 is a meteorite that came from Mars. Prospectors found it in the Sahara Desert in 2022.
  • Analysis of this rock suggests Mars began to lose its water very early in its history.
  • Plus, it reveals Mars had a crust similar to granite, which is surprising given the planet lacks plate tectonics.

We’ve never needed good science more than we do right now. Support EarthSky in 2026 and help us keep it going strong.

Teghaza 001, the oldest known Mars meteorite

Many pieces of Martian material have been ejected from the red planet and reached Earth as meteorites. And one of the more recently discovered Martian meteorites might be the oldest yet.

That’s what a team of scientists, led by the California Institute of Technology (Caltech), said on July 16, 2026. Prospectors found the meteorite – named Teghaza 001 – in the Sahara Desert in September 2022. And researchers have identified the piece of Mars’ crust as being over 4.1 billion years old.

The meteorite hints that the planet was already losing its water at that early stage in its life. Plus, it points to a granite-like crust on ancient Mars. That’s surprising, as the formation of granite on Earth is associated with tectonic activity … and Mars lacks plate tectonics.

The not-yet peer-reviewed paper is available as a preprint on the ESS Open Archive (April 14, 2026). Additional papers are also expected.

This meteorite, called Teghaza 001, “will revolutionize the way that we think about early Mars.”Learn more: https://scim.ag/4yDBSYK

Science Magazine (@science.org) 2026-07-21T22:40:01.528162083Z

A view into Mars’ past

Paper co-author Lee Saper is a geochemist at NASA’s Jet Propulsion Laboratory (JPL). He gave a talk at the Goldschmidt geochemistry conference in Montreal, Canada, on July 14. He said that the meteorite:

… will revolutionize the way that we think about early Mars.

And he’s likely right.

Teghaza 001 is only the second known Martian meteorite from the Martian crust in the earliest period of the planet’s history. The other one is Allan Hills 84001. So now, scientists have two meteorites to work with instead of just one. Lydia Hallis, a planetary scientist at the University of Glasgow, said:

We’ve doubled our old meteorites. There will be a lot of people, including me, who want to get a piece of this.

So what does the meteorite show?

Tegzaza is rich in both zircons and silicon. Zircon minerals contain tiny amounts of uranium. The uranium decays into lead over time. Since it decays at a known rate, scientists can use it to determine the age of the meteorite.

If the zircon minerals melt or are exposed to fluids, though, then their “clocks” are reset to zero. This means that the meteorite might be even older than 4.1 billion years. Christopher Herd, a geologist at the University of Alberta, said:

There’s more of a story to this rock than most other Martian meteorites.

Single bright white, speckled rock sitting by itself in a field of much darker rocks.
View larger. | NASA’s Perseverance rover found this unusual speckled white rock called Atoko Point last year. It has a granite-like appearance and contains feldspar, one of the key components of granite on Earth. Image via NASA/ JPL-Caltech/ ASU/ MSSS/ LiveScience.

Mars meteorite hints at granite-like crust on ancient Mars

But there was another surprise in the meteorite: it contained a lot of silicon. This hinted at granite-like rocks on ancient Mars. As Eva Scheller, a planetary scientist at Stanford University, noted:

It’s very strange; we don’t expect that.

Scientists never expected Mars to have much granite since it lacks plate tectonics (the division of a planet’s upper crust into multiple different pieces, or plates). On Earth, granite forms from cooling magma. And most of that magma is generated by the movement of tectonic plates. Meanwhile, most of Mars’ crust is composed of solid basalt.

But it’s starting to look like Mars did once have at least some granite, or granite-like rock. Impacts from meteorites have exposed some deposits. And last year, the Perseverance rover discovered a rock outcrop, called Plankeholmane, that looks a lot like granite on Earth. It contained quartz, a key component of granite.

And last year, the rover found an odd speckled white rock called Atoko Point that also appeared quite granite-like. It contained pyroxene and feldspar. Feldspar is also a component of granite on Earth.

How was Mars able to produce such deposits without plate tectonics? Scientists don’t know yet. This evidence also points to complex magma systems on early Mars, as does this other recent study.

Serious-looking young woman with pulled-back black hair, wearing a scarf.
Yang liu at Caltech is the lead author of the new study about the Teghaza 001 meteorite from Mars. Image via Caltech.

When Mars dried up

The meteorite also provides valuable clues about past water on Mars. Both it and the Allan Hills meteorite show that Mars had more water early in its history. But they also indicate that Mars began to lose its water early on, as the planet’s magnetic field disappeared and the atmosphere thinned and became much colder. Considering that these meteorites are at least 4.1 billion years old, and Mars – like Earth – formed some 4.5 billion years ago, this loss of water seems to have come in the planet’s infancy.

The clues come from the ratios of hydrogen in the meteorites. When Mars began to lose its water, the higher ratio of hydrogen – the primary component of water – to deuterium dropped. Super said:

This is the product of rapid hydrogen loss from the juvenile Martian atmosphere.

The new analysis of Teghaza 001 has provided new clues about Mars’ ancient past. And it also raises new questions. It will be interesting to see what else it and similar Mars meteorites reveal!

Bottom line: A new analysis of the the oldest known Mars meteorite, Teghaza 001, reveals evidence for a granite-like crust and the start of the loss of water on early Mars.

Source: Teghaza 001: An ancient Martian gabbroic diorite derived from previously unsampled Martian crust and mantle

Via Science

Read more: A famous Mars meteorite, now with nitrogen

Read more: Methane in Mars meteorites = life?

The post Oldest Mars meteorite reveals Mars lost its water early first appeared on EarthSky.



from EarthSky https://ift.tt/PEl6v2M
Mars meteorite: Smooth, flat gray surface, partly light and partly darker, with dark cracks in it.
View larger. | Closeup of the Teghaza 001 Mars meteorite. A new analysis of this ancient piece of the red planet reveals it was starting to lose its water over 4 billion years ago. Image via NASA.
  • Teghaza 001 is a meteorite that came from Mars. Prospectors found it in the Sahara Desert in 2022.
  • Analysis of this rock suggests Mars began to lose its water very early in its history.
  • Plus, it reveals Mars had a crust similar to granite, which is surprising given the planet lacks plate tectonics.

We’ve never needed good science more than we do right now. Support EarthSky in 2026 and help us keep it going strong.

Teghaza 001, the oldest known Mars meteorite

Many pieces of Martian material have been ejected from the red planet and reached Earth as meteorites. And one of the more recently discovered Martian meteorites might be the oldest yet.

That’s what a team of scientists, led by the California Institute of Technology (Caltech), said on July 16, 2026. Prospectors found the meteorite – named Teghaza 001 – in the Sahara Desert in September 2022. And researchers have identified the piece of Mars’ crust as being over 4.1 billion years old.

The meteorite hints that the planet was already losing its water at that early stage in its life. Plus, it points to a granite-like crust on ancient Mars. That’s surprising, as the formation of granite on Earth is associated with tectonic activity … and Mars lacks plate tectonics.

The not-yet peer-reviewed paper is available as a preprint on the ESS Open Archive (April 14, 2026). Additional papers are also expected.

This meteorite, called Teghaza 001, “will revolutionize the way that we think about early Mars.”Learn more: https://scim.ag/4yDBSYK

Science Magazine (@science.org) 2026-07-21T22:40:01.528162083Z

A view into Mars’ past

Paper co-author Lee Saper is a geochemist at NASA’s Jet Propulsion Laboratory (JPL). He gave a talk at the Goldschmidt geochemistry conference in Montreal, Canada, on July 14. He said that the meteorite:

… will revolutionize the way that we think about early Mars.

And he’s likely right.

Teghaza 001 is only the second known Martian meteorite from the Martian crust in the earliest period of the planet’s history. The other one is Allan Hills 84001. So now, scientists have two meteorites to work with instead of just one. Lydia Hallis, a planetary scientist at the University of Glasgow, said:

We’ve doubled our old meteorites. There will be a lot of people, including me, who want to get a piece of this.

So what does the meteorite show?

Tegzaza is rich in both zircons and silicon. Zircon minerals contain tiny amounts of uranium. The uranium decays into lead over time. Since it decays at a known rate, scientists can use it to determine the age of the meteorite.

If the zircon minerals melt or are exposed to fluids, though, then their “clocks” are reset to zero. This means that the meteorite might be even older than 4.1 billion years. Christopher Herd, a geologist at the University of Alberta, said:

There’s more of a story to this rock than most other Martian meteorites.

Single bright white, speckled rock sitting by itself in a field of much darker rocks.
View larger. | NASA’s Perseverance rover found this unusual speckled white rock called Atoko Point last year. It has a granite-like appearance and contains feldspar, one of the key components of granite on Earth. Image via NASA/ JPL-Caltech/ ASU/ MSSS/ LiveScience.

Mars meteorite hints at granite-like crust on ancient Mars

But there was another surprise in the meteorite: it contained a lot of silicon. This hinted at granite-like rocks on ancient Mars. As Eva Scheller, a planetary scientist at Stanford University, noted:

It’s very strange; we don’t expect that.

Scientists never expected Mars to have much granite since it lacks plate tectonics (the division of a planet’s upper crust into multiple different pieces, or plates). On Earth, granite forms from cooling magma. And most of that magma is generated by the movement of tectonic plates. Meanwhile, most of Mars’ crust is composed of solid basalt.

But it’s starting to look like Mars did once have at least some granite, or granite-like rock. Impacts from meteorites have exposed some deposits. And last year, the Perseverance rover discovered a rock outcrop, called Plankeholmane, that looks a lot like granite on Earth. It contained quartz, a key component of granite.

And last year, the rover found an odd speckled white rock called Atoko Point that also appeared quite granite-like. It contained pyroxene and feldspar. Feldspar is also a component of granite on Earth.

How was Mars able to produce such deposits without plate tectonics? Scientists don’t know yet. This evidence also points to complex magma systems on early Mars, as does this other recent study.

Serious-looking young woman with pulled-back black hair, wearing a scarf.
Yang liu at Caltech is the lead author of the new study about the Teghaza 001 meteorite from Mars. Image via Caltech.

When Mars dried up

The meteorite also provides valuable clues about past water on Mars. Both it and the Allan Hills meteorite show that Mars had more water early in its history. But they also indicate that Mars began to lose its water early on, as the planet’s magnetic field disappeared and the atmosphere thinned and became much colder. Considering that these meteorites are at least 4.1 billion years old, and Mars – like Earth – formed some 4.5 billion years ago, this loss of water seems to have come in the planet’s infancy.

The clues come from the ratios of hydrogen in the meteorites. When Mars began to lose its water, the higher ratio of hydrogen – the primary component of water – to deuterium dropped. Super said:

This is the product of rapid hydrogen loss from the juvenile Martian atmosphere.

The new analysis of Teghaza 001 has provided new clues about Mars’ ancient past. And it also raises new questions. It will be interesting to see what else it and similar Mars meteorites reveal!

Bottom line: A new analysis of the the oldest known Mars meteorite, Teghaza 001, reveals evidence for a granite-like crust and the start of the loss of water on early Mars.

Source: Teghaza 001: An ancient Martian gabbroic diorite derived from previously unsampled Martian crust and mantle

Via Science

Read more: A famous Mars meteorite, now with nitrogen

Read more: Methane in Mars meteorites = life?

The post Oldest Mars meteorite reveals Mars lost its water early first appeared on EarthSky.



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Vulpecula the Fox lies inside the Summer Triangle

Star chart: Large triangle with bright stars at corners and 3 labeled small constellations in and near it.
In the east on June, July and August evenings, you’ll find the large pattern of the Summer Triangle, made of 3 bright stars. And from a dark sky, you can also spot Vulpecula the Fox inside the triangle. Chart via EarthSky.

Your support = more science, more stars, more wonder. Donate to EarthSky and be part of something bigger.

Vulpecula the Fox is not an ancient constellation. Instead, it’s one of many created by Johannes Hevelius in the 17th century. Hevelius carved a lot of new constellations out of dim regions of sky next to better-known constellations. Vulpecula is one of the small constellations that lies inside the famous asterism of the Summer Triangle. And it contains two favorite targets of amateur astronomers.

Locating Vulpecula the Fox

Although Vulpecula the Fox is a dim constellation, you can find it easily under dark skies because of its location within the Summer Triangle. Only Vulpecula and Sagitta the Arrow reside within the boundaries of this star pattern.

If you don’t know how to find the Summer Triangle, look for three bright stars rising in the east after dark. These stars are Altair in Aquila the Eagle, Deneb in Cygnus the Swan and Vega in Lyra the Harp. Vulpecula lies near the head of Cygnus the Swan, near the colorful double star Albireo.

Stars in Vulpecula

Vulpecula is small in size (ranking 55th out of 88 constellations) and contains no bright stars of note. But that doesn’t mean it has little to offer!

The star grouping that brings amateur astronomers to Vulpecula is the Coathanger. The Coathanger has a few other names, such as Brocchi’s Cluster and Collinder 399. Although it’s called a cluster, studies have shown that it’s not a cluster in the formal sense – a group of gravitationally connected stars – but instead just a chance alignment of stars. This becomes more clear when you learn that the distances to its 10 or so stars span a vast range, including 218 light-years, 400 light-years, 760 light-years, 901 light-years and 1,132 light-years.

The Coathanger consists of stars of magnitude 5 and 6. They are arranged in a horizontal row with a hook shape sticking out from its middle, meaning they very much resemble a coathanger. You can see this best through binoculars or a low-power telescope. Through binoculars in the Northern Hemisphere, the Coathanger will appear upside down, but through the inverted view of a telescope, it appears right side up. And it’s the opposite for those in the Southern Hemisphere.

You can find the Coathanger about halfway between Albireo and Zeta Aquilae, the wingtip of Aquila the Eagle.

Coathanger cluster: 6 stars in line with 4 stars making hook below them against dense, crisp star field.
The Coathanger Cluster looks like its namesake. Image via Wikimedia Commons.
White star chart with black dots for stars and green lines for constellations.
The stars of Vulpecula the Fox. Image via IAU.

The Dumbbell Nebula in Vulpecula

The Dumbbell Nebula is another favorite target of amateur astronomers in Vulpecula.

This nebula lies about 8 1/2 degrees east of Albireo. Also known as M27, it glows at magnitude 8.1.

The Dumbbell Nebula became the first known planetary nebula when Charles Messier discovered it in 1764.

You can see the Dumbbell in binoculars, and even a small telescope can bring out its slight hourglass shape. The nebula, which lies about 1,360 light-years away, was created when the central star blew off its envelope of gas at the end of its life.

A small, mostly blue spherical cocoon, apparently with several shells, among thousands of stars.
View at EarthSky Community Photos. | Mario Rana in Hampton, Virginia, captured the Dumbbell Nebula (Messier 27) in the constellation Vulpecula on October 16, 2025. Thank you, Mario!

Bottom line: Vulpecula the Fox is a small constellation that lies inside the Summer Triangle. Amateur astronomers go here to spot the Coathanger Cluster and the Dumbbell Nebula.

The post Vulpecula the Fox lies inside the Summer Triangle first appeared on EarthSky.



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Star chart: Large triangle with bright stars at corners and 3 labeled small constellations in and near it.
In the east on June, July and August evenings, you’ll find the large pattern of the Summer Triangle, made of 3 bright stars. And from a dark sky, you can also spot Vulpecula the Fox inside the triangle. Chart via EarthSky.

Your support = more science, more stars, more wonder. Donate to EarthSky and be part of something bigger.

Vulpecula the Fox is not an ancient constellation. Instead, it’s one of many created by Johannes Hevelius in the 17th century. Hevelius carved a lot of new constellations out of dim regions of sky next to better-known constellations. Vulpecula is one of the small constellations that lies inside the famous asterism of the Summer Triangle. And it contains two favorite targets of amateur astronomers.

Locating Vulpecula the Fox

Although Vulpecula the Fox is a dim constellation, you can find it easily under dark skies because of its location within the Summer Triangle. Only Vulpecula and Sagitta the Arrow reside within the boundaries of this star pattern.

If you don’t know how to find the Summer Triangle, look for three bright stars rising in the east after dark. These stars are Altair in Aquila the Eagle, Deneb in Cygnus the Swan and Vega in Lyra the Harp. Vulpecula lies near the head of Cygnus the Swan, near the colorful double star Albireo.

Stars in Vulpecula

Vulpecula is small in size (ranking 55th out of 88 constellations) and contains no bright stars of note. But that doesn’t mean it has little to offer!

The star grouping that brings amateur astronomers to Vulpecula is the Coathanger. The Coathanger has a few other names, such as Brocchi’s Cluster and Collinder 399. Although it’s called a cluster, studies have shown that it’s not a cluster in the formal sense – a group of gravitationally connected stars – but instead just a chance alignment of stars. This becomes more clear when you learn that the distances to its 10 or so stars span a vast range, including 218 light-years, 400 light-years, 760 light-years, 901 light-years and 1,132 light-years.

The Coathanger consists of stars of magnitude 5 and 6. They are arranged in a horizontal row with a hook shape sticking out from its middle, meaning they very much resemble a coathanger. You can see this best through binoculars or a low-power telescope. Through binoculars in the Northern Hemisphere, the Coathanger will appear upside down, but through the inverted view of a telescope, it appears right side up. And it’s the opposite for those in the Southern Hemisphere.

You can find the Coathanger about halfway between Albireo and Zeta Aquilae, the wingtip of Aquila the Eagle.

Coathanger cluster: 6 stars in line with 4 stars making hook below them against dense, crisp star field.
The Coathanger Cluster looks like its namesake. Image via Wikimedia Commons.
White star chart with black dots for stars and green lines for constellations.
The stars of Vulpecula the Fox. Image via IAU.

The Dumbbell Nebula in Vulpecula

The Dumbbell Nebula is another favorite target of amateur astronomers in Vulpecula.

This nebula lies about 8 1/2 degrees east of Albireo. Also known as M27, it glows at magnitude 8.1.

The Dumbbell Nebula became the first known planetary nebula when Charles Messier discovered it in 1764.

You can see the Dumbbell in binoculars, and even a small telescope can bring out its slight hourglass shape. The nebula, which lies about 1,360 light-years away, was created when the central star blew off its envelope of gas at the end of its life.

A small, mostly blue spherical cocoon, apparently with several shells, among thousands of stars.
View at EarthSky Community Photos. | Mario Rana in Hampton, Virginia, captured the Dumbbell Nebula (Messier 27) in the constellation Vulpecula on October 16, 2025. Thank you, Mario!

Bottom line: Vulpecula the Fox is a small constellation that lies inside the Summer Triangle. Amateur astronomers go here to spot the Coathanger Cluster and the Dumbbell Nebula.

The post Vulpecula the Fox lies inside the Summer Triangle first appeared on EarthSky.



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Delta Aquariid meteor shower: All you need to know in 2026

Meteor shower chart: Star chart with radial arrows from a spot below the Great Square of Pegasus and above the star Fomalhaut.
The radiant point for the Delta Aquariid meteor shower – the point in the sky that these meteors seem to fly from – 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.

Your support = more science, more stars, more wonder. Donate to EarthSky and be part of something bigger.?

Delta Aquariid meteor shower

Predicted peak: The peak is predicted** for 10 UTC on July 30, 2026. 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 below.
Nearest moon phase: In 2026, the full moon falls at 14:36 UTC on July 29. Take advantage of the moon-free mornings – after midnight – the week before this date to see the most Delta Aquariids (and 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. 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. But the shower can be excellent 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, or glowing gas trails that last a second or two after the meteor has passed.

Read more: Meteors in moonlight: 6 tips for watching

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

Delta Aquariid meteor shower photos from the EarthSky community

Submit your photos to EarthSky here

Several thin, bright lines in a dark, starry sky above 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 I checked the frames I saw there were 4 to 6 meteors on a 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, pink and green light alongside cloudy band of Milky Way in densely starry sky.
View at EarthSky Community Photos. | James Reynolds in Asheville, North Carolina, captured this image 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 2026, watch in the moon-free mornings – after midnight – the week before the peak 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 2026 first appeared on EarthSky.



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Meteor shower chart: Star chart with radial arrows from a spot below the Great Square of Pegasus and above the star Fomalhaut.
The radiant point for the Delta Aquariid meteor shower – the point in the sky that these meteors seem to fly from – 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.

Your support = more science, more stars, more wonder. Donate to EarthSky and be part of something bigger.?

Delta Aquariid meteor shower

Predicted peak: The peak is predicted** for 10 UTC on July 30, 2026. 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 below.
Nearest moon phase: In 2026, the full moon falls at 14:36 UTC on July 29. Take advantage of the moon-free mornings – after midnight – the week before this date to see the most Delta Aquariids (and 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. 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. But the shower can be excellent 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, or glowing gas trails that last a second or two after the meteor has passed.

Read more: Meteors in moonlight: 6 tips for watching

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

Delta Aquariid meteor shower photos from the EarthSky community

Submit your photos to EarthSky here

Several thin, bright lines in a dark, starry sky above 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 I checked the frames I saw there were 4 to 6 meteors on a 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, pink and green light alongside cloudy band of Milky Way in densely starry sky.
View at EarthSky Community Photos. | James Reynolds in Asheville, North Carolina, captured this image 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 2026, watch in the moon-free mornings – after midnight – the week before the peak 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 2026 first appeared on EarthSky.



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M6 and M7: Open star clusters in the Scorpion’s Tail

M6 and M7: Night sky with two close-together, brilliant stars and two patches of multiple stars nearby.
In a dark sky, you’ll see 2 famous star clusters – M6 and M7 – in the constellation Scorpius the Scorpion. In this photo, Messier 7 – aka Ptolemy’s Cluster – is above the tree on the left. Messier 6, the Butterfly Cluster, is a bit smaller, positioned near the center top of the image. And Shaula and Lesath, the stinger stars in Scorpius, are prominent in the lower right. Image via Tom and Jane Wildoner/ Dark Side Observatory/ Flickr. Used with permission.
  • The star clusters M6 (Butterfly Cluster) and M7 (Ptolemy’s Cluster) are near the tail of the Scorpion in the constellation Scorpius. Look for them on dark Northern Hemisphere summer nights!
  • Both M6 and M7 are open star clusters, which means they are groups of stars that formed together from the same cloud of gas and dust, making them like star siblings.
  • You can spot these clusters with your unaided eye on a dark, moonless night, but they look even more beautiful through binoculars.

M6 and M7: Open star clusters in the Scorpion’s Tail

Two spectacular star clusters glitter near Scorpius the Scorpion’s stinger stars, Shaula and Lesath. Messier 6 and Messier 7 – or M6 and M7 – are open star clusters. Each cluster is a group of stars formed from the same huge cloud of gas.

These two clusters are visible on summer evenings in the Northern Hemisphere, or winter evenings in the Southern Hemisphere. They’re best viewed in a dark sky, and are a stunning sight through binoculars.

Star chart: dots and lines making up hook-shaped constellation Scorpius with stars and clusters labeled.
The constellation Scorpius with the positions of the star clusters M7 and M6 marked. Chart by EarthSky.

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How to find M6 and M7

These star clusters are easy to spot in a dark sky near the curved tail of the constellation Scorpius the Scorpion. Scorpius is shaped like the letter J. And the two stars, Shaula and Lesath – at the end of the curved part of the J – mark the end of the Scorpion’s Tail. They’re known as the Cat’s Eyes, or the stinger of Scorpius.

Plus, if you draw an imaginary line from Lesath through Shaula, you’ll find M7, which is the brighter and larger of the two star clusters. Then from M7, you find M6 only a short hop away.

And although M6 and M7 are visible to the unaided eye on a dark, moonless night, the brilliance and beauty of these deep sky objects is magnificent through binoculars.

If you’re in the northern U.S., Canada or a similar latitude, you’ll need an unobstructed horizon toward the south to find M6 and M7. They are highest in the sky when due south, and even then never climb very high in the sky. Meanwhile, from latitudes like those in the southern U.S., the clusters are easy to spot at their highest in the south, above the Scorpion’s Tail. Generally, Scorpius is much easier to view from the equator and most of the Southern Hemisphere.

Rich part of the Milky Way showing the star clusters M6, M7 plus the Stinger Stars of Scorpius.
View at EarthSky Community Photos. | Dr Ski captured this image from the Philippines and wrote: “The Scorpion’s stinger is comprised of Shaula and Lesath. These stars point the way to magnificent Ptolemy’s Open Cluster (M7). Just 3 degrees to the northwest is the Butterfly Cluster (M6). Binoculars will show you these clusters, along with all the dark nebulae snaking around this region!” Thank you, Dr Ski!

Best time to view

Consequently, in mid-June, these clusters are visible in the sky around midnight (1 a.m. daylight saving time in the U.S.). And keep in mind that all the stars (and star clusters) return to the same place in the sky some four minutes earlier with each passing day, or two hours earlier with each passing month. Therefore, M6 and M7 appear highest in the sky at about 10 p.m. (11 p.m. daylight saving time) in mid-July, and 8 p.m. (9 p.m. daylight saving time) in mid-August.

M6 and M7 science

Even though M6 (Butterfly Cluster) and M7 (Ptolemy’s Cluster) appear close together on the sky’s dome, they are far apart in space. Indeed, M6 is about 1,600 light-years away and shines at magnitude 4.2. M7 is about 980 light-years and shines at magnitude 3.3. So, the clusters are not related to each other, but only appear near each other along our line of sight.

But, within each cluster, the stars are related. Each cluster was born from a single interstellar cloud of gas and dust. The hundreds of stars in each cluster are indeed sibling stars, in that they are gravitationally bound to one another and travel in the same direction through space. Therefore, astronomers call such a collection of stars an open star cluster.

A group of mostly blue-white stars against dense field of fainter stars.
Messier 6 through a wide field telescope and camera. Image via Fred Espenak. Used with permission.
Group of mostly blue-white stars against an extremely dense star field with some dark lanes.
Messier 7 through a wide field telescope and camera. Image via Fred Espenak. Used with permission.

The clusters are in the thick of the Milky Way

M6 and M7 reside near the galactic equator, the region on the sky’s dome rich with star clusters, star clouds and nebulae. Once you find M6 and M7, try locating other deep-sky binocular doubles, such as M8 and M20. And also check out M16 and M17. These deep-sky wonders loom farther away. Also, M6 and M7 are open star clusters. But M8 and M20, and M16 and M17, are nebulae where stars are forming.

Bottom line: Messier 6 and Messier 7 are striking star clusters near the tail of Scorpius. M6 and M7 are best in dark sky conditions through binoculars.

The post M6 and M7: Open star clusters in the Scorpion’s Tail first appeared on EarthSky.



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M6 and M7: Night sky with two close-together, brilliant stars and two patches of multiple stars nearby.
In a dark sky, you’ll see 2 famous star clusters – M6 and M7 – in the constellation Scorpius the Scorpion. In this photo, Messier 7 – aka Ptolemy’s Cluster – is above the tree on the left. Messier 6, the Butterfly Cluster, is a bit smaller, positioned near the center top of the image. And Shaula and Lesath, the stinger stars in Scorpius, are prominent in the lower right. Image via Tom and Jane Wildoner/ Dark Side Observatory/ Flickr. Used with permission.
  • The star clusters M6 (Butterfly Cluster) and M7 (Ptolemy’s Cluster) are near the tail of the Scorpion in the constellation Scorpius. Look for them on dark Northern Hemisphere summer nights!
  • Both M6 and M7 are open star clusters, which means they are groups of stars that formed together from the same cloud of gas and dust, making them like star siblings.
  • You can spot these clusters with your unaided eye on a dark, moonless night, but they look even more beautiful through binoculars.

M6 and M7: Open star clusters in the Scorpion’s Tail

Two spectacular star clusters glitter near Scorpius the Scorpion’s stinger stars, Shaula and Lesath. Messier 6 and Messier 7 – or M6 and M7 – are open star clusters. Each cluster is a group of stars formed from the same huge cloud of gas.

These two clusters are visible on summer evenings in the Northern Hemisphere, or winter evenings in the Southern Hemisphere. They’re best viewed in a dark sky, and are a stunning sight through binoculars.

Star chart: dots and lines making up hook-shaped constellation Scorpius with stars and clusters labeled.
The constellation Scorpius with the positions of the star clusters M7 and M6 marked. Chart by EarthSky.

We live in uncertain times. But things are always so much more peaceful, looking up. Please help EarthSky keep going!

How to find M6 and M7

These star clusters are easy to spot in a dark sky near the curved tail of the constellation Scorpius the Scorpion. Scorpius is shaped like the letter J. And the two stars, Shaula and Lesath – at the end of the curved part of the J – mark the end of the Scorpion’s Tail. They’re known as the Cat’s Eyes, or the stinger of Scorpius.

Plus, if you draw an imaginary line from Lesath through Shaula, you’ll find M7, which is the brighter and larger of the two star clusters. Then from M7, you find M6 only a short hop away.

And although M6 and M7 are visible to the unaided eye on a dark, moonless night, the brilliance and beauty of these deep sky objects is magnificent through binoculars.

If you’re in the northern U.S., Canada or a similar latitude, you’ll need an unobstructed horizon toward the south to find M6 and M7. They are highest in the sky when due south, and even then never climb very high in the sky. Meanwhile, from latitudes like those in the southern U.S., the clusters are easy to spot at their highest in the south, above the Scorpion’s Tail. Generally, Scorpius is much easier to view from the equator and most of the Southern Hemisphere.

Rich part of the Milky Way showing the star clusters M6, M7 plus the Stinger Stars of Scorpius.
View at EarthSky Community Photos. | Dr Ski captured this image from the Philippines and wrote: “The Scorpion’s stinger is comprised of Shaula and Lesath. These stars point the way to magnificent Ptolemy’s Open Cluster (M7). Just 3 degrees to the northwest is the Butterfly Cluster (M6). Binoculars will show you these clusters, along with all the dark nebulae snaking around this region!” Thank you, Dr Ski!

Best time to view

Consequently, in mid-June, these clusters are visible in the sky around midnight (1 a.m. daylight saving time in the U.S.). And keep in mind that all the stars (and star clusters) return to the same place in the sky some four minutes earlier with each passing day, or two hours earlier with each passing month. Therefore, M6 and M7 appear highest in the sky at about 10 p.m. (11 p.m. daylight saving time) in mid-July, and 8 p.m. (9 p.m. daylight saving time) in mid-August.

M6 and M7 science

Even though M6 (Butterfly Cluster) and M7 (Ptolemy’s Cluster) appear close together on the sky’s dome, they are far apart in space. Indeed, M6 is about 1,600 light-years away and shines at magnitude 4.2. M7 is about 980 light-years and shines at magnitude 3.3. So, the clusters are not related to each other, but only appear near each other along our line of sight.

But, within each cluster, the stars are related. Each cluster was born from a single interstellar cloud of gas and dust. The hundreds of stars in each cluster are indeed sibling stars, in that they are gravitationally bound to one another and travel in the same direction through space. Therefore, astronomers call such a collection of stars an open star cluster.

A group of mostly blue-white stars against dense field of fainter stars.
Messier 6 through a wide field telescope and camera. Image via Fred Espenak. Used with permission.
Group of mostly blue-white stars against an extremely dense star field with some dark lanes.
Messier 7 through a wide field telescope and camera. Image via Fred Espenak. Used with permission.

The clusters are in the thick of the Milky Way

M6 and M7 reside near the galactic equator, the region on the sky’s dome rich with star clusters, star clouds and nebulae. Once you find M6 and M7, try locating other deep-sky binocular doubles, such as M8 and M20. And also check out M16 and M17. These deep-sky wonders loom farther away. Also, M6 and M7 are open star clusters. But M8 and M20, and M16 and M17, are nebulae where stars are forming.

Bottom line: Messier 6 and Messier 7 are striking star clusters near the tail of Scorpius. M6 and M7 are best in dark sky conditions through binoculars.

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Have we found the first exomoon … around a brown dwarf?


Astronomers have discovered an object orbiting a brown dwarf or “failed star”. Is it the first exomoon, or moon outside our solar system? Astronomers are debating what to call it. Why? Because moons orbit planets … And this exomoon is orbiting a brown dwarf, which is an object that’s too massive to be a planet but not massive enough to shine like a star. Video via ESO.

Did we find an exomoon around a brown dwarf?

Exomoons are moons that exist outside our own solar system. We’ve yet to definitively find a single one! That’s because they are small and dim, circling exoplanets that are also small and dim, hidden in the glare of the stars they orbit. But on July 22, 2026, the European Southern Observatory said astronomers using the Very Large Telescope in Chile believe they have detected an exomoon.

Only, there’s one problem: it doesn’t orbit a planet. Instead, it orbits a brown dwarf. A brown dwarf is an object that’s too massive to be considered a planet, but not massive enough to ignite and shine like a star. And this particular brown dwarf orbits a star, named CD-35 2722. So astronomers are debating what to call the newly discovered object. Is it the first discovered exomoon, or something else?

The researchers published their peer-reviewed paper on July 22, 2026, in the journal Nature.

A ‘super weird’ system

Not all brown dwarfs orbit stars, but this one does. The star in this system is named CD-35 2722, and it’s about half the mass of our sun. But even though the brown dwarf orbits this star, it’s not a planet, because it’s too massive. Brown dwarfs are so massive compared to planets that they’re sometimes called “failed stars”. Though far heavier than the objects we call planets, they aren’t quite massive enough to begin nuclear fusion and shine like a star does.

And then we have the newly discovered object, which orbits the brown dwarf. Normally we think of a moon as something that orbits a planet, which orbits a star. So what orbits a brown dwarf? Is it an exomoon? That’s what astronomers are having to decide: the semantics of the system. In any case, the lead author of the new study, Kevin Hoy, an ESO student in Chile, calls it:

super weird.

Right now, the team is calling the object an exosatellite. The object is at least as massive as Jupiter. Meanwhile, the brown dwarf it orbits is about 30 times as massive as Jupiter. Hoy said:

This system is somewhat hard to define using solar-system-based words like ‘planet’ and ‘moon’. The exosatellite is clearly massive enough to be a planet, but it does not orbit a star, though it orbits an object that orbits a star. Being the third wheel in this system makes us want to call it a moon, even if it is nothing like the small, rocky moons we have in our system.

First exomoon: Star at left, world with bands in middle, larger world with glowing bands at right.
This is an artist’s concept of the star system CD-35 2722. The star, about half the mass of our sun, is on the left. The large object on the right is the brown dwarf that orbits the star. And at center is the newly discovered object orbiting the brown dwarf. Should it be called an exomoon, even though it doesn’t orbit a planet? It’s massive enough to be a planet, but planets orbit stars, not brown dwarfs. Image via ESO/M. Kornmesser.

The name game

Humans have a need to neatly categorize the things they encounter in the world. But nature is not so rigid. Pluto itself did not change when its classification changed from planet to dwarf planet. And asteroids, comets and meteors are all leftover material from the formation of our solar system under different names.

But naming things – or nomenclature – is part of the scientific process. It’s just not always easy to do. Co-author Alice Zurlo of Universidad Diego Portales said:

We have a clear delineation between the planets and the sun in the solar system, so defining things like moons is simple. In the CD-35 2722 system, where we are blurring the lines between stars, planets and moons, the whole thing becomes more complicated to describe.

Exomoons around exoplanets

Astronomers didn’t confirm the first exoplanet – or planet around a star other than the sun – until 1992. Because they are so small and dim compared to their parent star, they are particularly hard to find. But astronomers long thought they were there. And now we’ve confirmed some 6,000 exoplanets.

So far, it’s been a similar story with exomoons. Astronomers assume there are many exomoons in other stellar systems, just as there are many moons in our solar system. It’s simply a challenge to find them. Astronomers have found exomoon candidates around distant exoplanets, but no confirmation yet.

This candidate exomoon – if it ends up with that label – has strong evidence. It’s causing the brown dwarf that it orbits to wobble. And those wobbles show up in the brown dwarf’s spectra. Zurlo said:

As exotic as it is, this system is truly unique and represents a breakthrough: the first plausible detection of an exosatellite.

Bottom line: Have astronomers found the first exomoon? We think of moons as objects that orbit planets. So what do we call this object, which orbits a brown dwarf?

Source: Planetary-Mass Exosatellite Detected Around a Star’s Substellar Companion

Via ESO

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Astronomers have discovered an object orbiting a brown dwarf or “failed star”. Is it the first exomoon, or moon outside our solar system? Astronomers are debating what to call it. Why? Because moons orbit planets … And this exomoon is orbiting a brown dwarf, which is an object that’s too massive to be a planet but not massive enough to shine like a star. Video via ESO.

Did we find an exomoon around a brown dwarf?

Exomoons are moons that exist outside our own solar system. We’ve yet to definitively find a single one! That’s because they are small and dim, circling exoplanets that are also small and dim, hidden in the glare of the stars they orbit. But on July 22, 2026, the European Southern Observatory said astronomers using the Very Large Telescope in Chile believe they have detected an exomoon.

Only, there’s one problem: it doesn’t orbit a planet. Instead, it orbits a brown dwarf. A brown dwarf is an object that’s too massive to be considered a planet, but not massive enough to ignite and shine like a star. And this particular brown dwarf orbits a star, named CD-35 2722. So astronomers are debating what to call the newly discovered object. Is it the first discovered exomoon, or something else?

The researchers published their peer-reviewed paper on July 22, 2026, in the journal Nature.

A ‘super weird’ system

Not all brown dwarfs orbit stars, but this one does. The star in this system is named CD-35 2722, and it’s about half the mass of our sun. But even though the brown dwarf orbits this star, it’s not a planet, because it’s too massive. Brown dwarfs are so massive compared to planets that they’re sometimes called “failed stars”. Though far heavier than the objects we call planets, they aren’t quite massive enough to begin nuclear fusion and shine like a star does.

And then we have the newly discovered object, which orbits the brown dwarf. Normally we think of a moon as something that orbits a planet, which orbits a star. So what orbits a brown dwarf? Is it an exomoon? That’s what astronomers are having to decide: the semantics of the system. In any case, the lead author of the new study, Kevin Hoy, an ESO student in Chile, calls it:

super weird.

Right now, the team is calling the object an exosatellite. The object is at least as massive as Jupiter. Meanwhile, the brown dwarf it orbits is about 30 times as massive as Jupiter. Hoy said:

This system is somewhat hard to define using solar-system-based words like ‘planet’ and ‘moon’. The exosatellite is clearly massive enough to be a planet, but it does not orbit a star, though it orbits an object that orbits a star. Being the third wheel in this system makes us want to call it a moon, even if it is nothing like the small, rocky moons we have in our system.

First exomoon: Star at left, world with bands in middle, larger world with glowing bands at right.
This is an artist’s concept of the star system CD-35 2722. The star, about half the mass of our sun, is on the left. The large object on the right is the brown dwarf that orbits the star. And at center is the newly discovered object orbiting the brown dwarf. Should it be called an exomoon, even though it doesn’t orbit a planet? It’s massive enough to be a planet, but planets orbit stars, not brown dwarfs. Image via ESO/M. Kornmesser.

The name game

Humans have a need to neatly categorize the things they encounter in the world. But nature is not so rigid. Pluto itself did not change when its classification changed from planet to dwarf planet. And asteroids, comets and meteors are all leftover material from the formation of our solar system under different names.

But naming things – or nomenclature – is part of the scientific process. It’s just not always easy to do. Co-author Alice Zurlo of Universidad Diego Portales said:

We have a clear delineation between the planets and the sun in the solar system, so defining things like moons is simple. In the CD-35 2722 system, where we are blurring the lines between stars, planets and moons, the whole thing becomes more complicated to describe.

Exomoons around exoplanets

Astronomers didn’t confirm the first exoplanet – or planet around a star other than the sun – until 1992. Because they are so small and dim compared to their parent star, they are particularly hard to find. But astronomers long thought they were there. And now we’ve confirmed some 6,000 exoplanets.

So far, it’s been a similar story with exomoons. Astronomers assume there are many exomoons in other stellar systems, just as there are many moons in our solar system. It’s simply a challenge to find them. Astronomers have found exomoon candidates around distant exoplanets, but no confirmation yet.

This candidate exomoon – if it ends up with that label – has strong evidence. It’s causing the brown dwarf that it orbits to wobble. And those wobbles show up in the brown dwarf’s spectra. Zurlo said:

As exotic as it is, this system is truly unique and represents a breakthrough: the first plausible detection of an exosatellite.

Bottom line: Have astronomers found the first exomoon? We think of moons as objects that orbit planets. So what do we call this object, which orbits a brown dwarf?

Source: Planetary-Mass Exosatellite Detected Around a Star’s Substellar Companion

Via ESO

The post Have we found the first exomoon … around a brown dwarf? first appeared on EarthSky.



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Our galaxy flipped after a collision, say astronomers


Watch this simulation of a galaxy flipped from edge-on to face-on after a collision with a massive dwarf galaxy. Astronomers said on July 21, 2026, that this scenario likely happened to our own Milky Way galaxy some 10 billion years ago. Video via Auriga Project and Thomas Tomlinson.

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Our galaxy flipped after a collision, say astronomers

Astronomers think that some 10 billion years ago, our Milky Way galaxy collided with another galaxy, which they’ve dubbed the Gaia Sausage. And on July 21, 2026, a team of astronomers at the Royal Astronomical Society’s National Astronomy Meeting said that this collision flipped the disk of our galaxy.

The team of astronomers, from Durham University in the U.K., used supercomputer simulations to study how 25 galaxies like our own would have evolved over billions of years. The simulations helped explain how the collision and aftermath resulted in our galaxy’s disk flipping by more than 90 degrees. And, they said, this scenario helps explain why stars in the halo around our galaxy behave the way they do.

The Milky Way galaxy and its clones

Our Milky Way is a spiral galaxy with a central bar. Most of the galaxy’s stars are in the bulge and disk, but there are other stars orbiting in a diffuse halo – a vast, much sparser sphere of stars – around the galaxy’s core and spiral arms.

These stars in the halo come from mergers, over time, with other smaller galaxies. The Gaia mission, which tracked the motions and distances of billions of stars, showed that the Milky Way’s halo is very slowly rotating. But scientists didn’t know why.

This is where the simulations came in. The researchers found that other galaxies with slowly rotating halos had a couple of things in common. First, these simulated galaxies experienced a major head-on merger with another galaxy during their evolution. And second, they experienced a disk flip. These two ingredients appeared to be the keys to creating the slowly rotating halo.

Lead researcher Kirill Batrakov at Durham University said:

We already know that the Milky Way had a massive head-on collision in the past with a galaxy known as Gaia-Sausage-Enceladus (often simply called the Gaia Sausage). So, we think that the Milky Way disk likely flipped in the past.

The Gaia Sausage hit us

This galaxy that hit us was a dwarf galaxy. It was particularly massive for a dwarf galaxy, but it was still smaller than the Milky Way.

Why do scientists call it the Gaia Sausage? Well, after the collision some 10 to 11 billion years ago, our galaxy absorbed the stars of the Gaia Sausage. The leftover stars from this galaxy now take long, elliptical paths – sausage-shaped, if you will – about the Milky Way’s center.

Oblique view of a spiral galaxy with very many little yellow arrows blasting through its center and on out.
Artist’s concept of the merger between the Milky Way and Gaia Sausage. The yellow arrows show the positions and motions of the stars from the Gaia Sausage in this early phase of the merger, as predicted by a computer simulation. Image via ESA (artist’s impression and composition)/ Koppelman, Villalobos and Helmi (simulation)/ NASA/ESA/Hubble (galaxy image)/ RAS.
Face-on spiral galaxy with very many short yellow arrows around the edge, most going out, some going in.
Artist’s concept showing remnants of the Gaia Sausage. Yellow arrows again show the positions and motions of the Gaia Sausage stars in the halo of our Milky Way. Image via ESA (artist’s impression and composition)/ Koppelman, Villalobos and Helmi (simulation)/ RAS.

Simulated galaxies with and without a flip

In the images below, we see two simulated galaxies. The first set of simulations are of a galaxy researchers call Halo 18. This galaxy underwent a disk flip. The one below it – simulated galaxy Halo 6 – did not have a collision or disk flip.

Galaxy flipped: 48 panels showing a spiral galaxy from different angles.
Views of a simulated galaxy the team calls Halo 18. After a head-on collision, the galaxy experiences a disk flip. You can see this by comparing the disk’s orientation at z=1.4 and z=0. The z and number at the bottom correspond to a redshift, which measures time. So z=0 is now, with larger numbers denoting events farther back in time. Each period of time illustrated in the simulation has a face-on and edge-on view. Image via Auriga Project/ RAS.
A grid showing 48 views of a spiral galaxy face on and from the side plus interactions.
Views of simulated galaxy Halo 6. It undergoes neither a head-on collision or disk flip. Image via Auriga Project/ RAS.

Insight into galactic evolution and dark matter

A collision and disk flip gives astronomers more insight into the history of our own galaxy. And it also provides insight into other galaxies similar to ours. Batrakov said:

Because we live inside the Milky Way, we can study it in more detail than any other galaxy, which makes it a key testbed for understanding galaxies more broadly.

Not every galaxy experiences a disk flip. But now it seems the Milky Way experienced at least one in the past. Batrakov said:

Finding that its disk flipped adds a new chapter to that story, one we must account for when placing the Milky Way in a broader context of other galaxies. What excites me the most is that this complex history can be reconstructed just from present-day observations.

And the insight could extend to the elusive substance astronomers call dark matter. Astronomers have already known from earlier measurements of the movements of our galaxy that an invisible dark matter halo surrounds the Milky Way. In fact, dark matter makes up 90% of the mass of our galaxy.

The new study found that the starry halo rotating around the Milky Way is closely linked to the rotation of its dark matter halo. So this suggests that the Gaia Sausage remnants, along with other smaller galaxies that collided with us, may have evolved in step with the dark matter halo.

Bottom line: Our galaxy flipped after a collision with a dwarf galaxy 10 billion years ago, changing the Milky Way’s evolution, new simulations suggest.

Via Royal Astronomical Society

Read more: Did galaxy-killing wind shape the early universe?

Read more: The black hole or galaxy: Which came 1st?

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Watch this simulation of a galaxy flipped from edge-on to face-on after a collision with a massive dwarf galaxy. Astronomers said on July 21, 2026, that this scenario likely happened to our own Milky Way galaxy some 10 billion years ago. Video via Auriga Project and Thomas Tomlinson.

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Our galaxy flipped after a collision, say astronomers

Astronomers think that some 10 billion years ago, our Milky Way galaxy collided with another galaxy, which they’ve dubbed the Gaia Sausage. And on July 21, 2026, a team of astronomers at the Royal Astronomical Society’s National Astronomy Meeting said that this collision flipped the disk of our galaxy.

The team of astronomers, from Durham University in the U.K., used supercomputer simulations to study how 25 galaxies like our own would have evolved over billions of years. The simulations helped explain how the collision and aftermath resulted in our galaxy’s disk flipping by more than 90 degrees. And, they said, this scenario helps explain why stars in the halo around our galaxy behave the way they do.

The Milky Way galaxy and its clones

Our Milky Way is a spiral galaxy with a central bar. Most of the galaxy’s stars are in the bulge and disk, but there are other stars orbiting in a diffuse halo – a vast, much sparser sphere of stars – around the galaxy’s core and spiral arms.

These stars in the halo come from mergers, over time, with other smaller galaxies. The Gaia mission, which tracked the motions and distances of billions of stars, showed that the Milky Way’s halo is very slowly rotating. But scientists didn’t know why.

This is where the simulations came in. The researchers found that other galaxies with slowly rotating halos had a couple of things in common. First, these simulated galaxies experienced a major head-on merger with another galaxy during their evolution. And second, they experienced a disk flip. These two ingredients appeared to be the keys to creating the slowly rotating halo.

Lead researcher Kirill Batrakov at Durham University said:

We already know that the Milky Way had a massive head-on collision in the past with a galaxy known as Gaia-Sausage-Enceladus (often simply called the Gaia Sausage). So, we think that the Milky Way disk likely flipped in the past.

The Gaia Sausage hit us

This galaxy that hit us was a dwarf galaxy. It was particularly massive for a dwarf galaxy, but it was still smaller than the Milky Way.

Why do scientists call it the Gaia Sausage? Well, after the collision some 10 to 11 billion years ago, our galaxy absorbed the stars of the Gaia Sausage. The leftover stars from this galaxy now take long, elliptical paths – sausage-shaped, if you will – about the Milky Way’s center.

Oblique view of a spiral galaxy with very many little yellow arrows blasting through its center and on out.
Artist’s concept of the merger between the Milky Way and Gaia Sausage. The yellow arrows show the positions and motions of the stars from the Gaia Sausage in this early phase of the merger, as predicted by a computer simulation. Image via ESA (artist’s impression and composition)/ Koppelman, Villalobos and Helmi (simulation)/ NASA/ESA/Hubble (galaxy image)/ RAS.
Face-on spiral galaxy with very many short yellow arrows around the edge, most going out, some going in.
Artist’s concept showing remnants of the Gaia Sausage. Yellow arrows again show the positions and motions of the Gaia Sausage stars in the halo of our Milky Way. Image via ESA (artist’s impression and composition)/ Koppelman, Villalobos and Helmi (simulation)/ RAS.

Simulated galaxies with and without a flip

In the images below, we see two simulated galaxies. The first set of simulations are of a galaxy researchers call Halo 18. This galaxy underwent a disk flip. The one below it – simulated galaxy Halo 6 – did not have a collision or disk flip.

Galaxy flipped: 48 panels showing a spiral galaxy from different angles.
Views of a simulated galaxy the team calls Halo 18. After a head-on collision, the galaxy experiences a disk flip. You can see this by comparing the disk’s orientation at z=1.4 and z=0. The z and number at the bottom correspond to a redshift, which measures time. So z=0 is now, with larger numbers denoting events farther back in time. Each period of time illustrated in the simulation has a face-on and edge-on view. Image via Auriga Project/ RAS.
A grid showing 48 views of a spiral galaxy face on and from the side plus interactions.
Views of simulated galaxy Halo 6. It undergoes neither a head-on collision or disk flip. Image via Auriga Project/ RAS.

Insight into galactic evolution and dark matter

A collision and disk flip gives astronomers more insight into the history of our own galaxy. And it also provides insight into other galaxies similar to ours. Batrakov said:

Because we live inside the Milky Way, we can study it in more detail than any other galaxy, which makes it a key testbed for understanding galaxies more broadly.

Not every galaxy experiences a disk flip. But now it seems the Milky Way experienced at least one in the past. Batrakov said:

Finding that its disk flipped adds a new chapter to that story, one we must account for when placing the Milky Way in a broader context of other galaxies. What excites me the most is that this complex history can be reconstructed just from present-day observations.

And the insight could extend to the elusive substance astronomers call dark matter. Astronomers have already known from earlier measurements of the movements of our galaxy that an invisible dark matter halo surrounds the Milky Way. In fact, dark matter makes up 90% of the mass of our galaxy.

The new study found that the starry halo rotating around the Milky Way is closely linked to the rotation of its dark matter halo. So this suggests that the Gaia Sausage remnants, along with other smaller galaxies that collided with us, may have evolved in step with the dark matter halo.

Bottom line: Our galaxy flipped after a collision with a dwarf galaxy 10 billion years ago, changing the Milky Way’s evolution, new simulations suggest.

Via Royal Astronomical Society

Read more: Did galaxy-killing wind shape the early universe?

Read more: The black hole or galaxy: Which came 1st?

The post Our galaxy flipped after a collision, say astronomers first appeared on EarthSky.



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Find M4: An easy to spot globular cluster near Antares

Star chart: Scorpius, a J-shaped constellation, with some stars labeled, on a blue background.
This chart shows the constellation Scorpius the Scorpion, holding the red star Antares at the its heart. Antares will lead you to a great globular cluster called Messier 4 (M4). It’s visible in the evenings for the next few months. Chart via EarthSky.

Bright red star Antares is easy to find in the prominent zodiacal constellation Scorpius the Scorpion. And if you look just slightly west of it through binoculars, you’ll see a small faint diffuse ball of light. Through a moderate-sized telescope, that fuzzy ball resolves into a tight collection of faint stars suspended in the darkness. That’s Messier 4, called M4 for short.

M4 is a globular star cluster. These balls of stars are some of the most ancient parts of our Milky Way galaxy.

M4 shines at magnitude +5.9, so it might just be visible to the unaided eye as a faint smudge on the sky under very dark skies.

Antares shines bright among a backdrop of stars, with M4 nearby, seen as a small compact grouping of many faint stars.
Astronomer and photographer Fred Espenak captured this image of Messier 4, with Antares to its left, using a small telescope. Image via Fred Espenak. Used with permission.

Find M4 in binoculars first

If you’ve never found a deep-sky object on your own before, M4 is a great place to start. Northern Hemisphere summer evenings – or Southern Hemisphere winter evenings – are your best bet for catching M4. It’s easy to find, because it’s right next to the first-magnitude star Antares, the brightest star in the constellation Scorpius the Scorpion.

In early June, Antares is highest in the sky around midnight your local time (1 a.m. daylight saving time). That means it’s high in the south for Northern Hemisphere viewers, and overhead for Southern Hemisphere viewers. The stars return to the same place in the sky some two hours earlier every month. So, Antares is highest up around 10 p.m. (11 p.m. daylight saving time) in early July, and 8 p.m. (9 p.m. daylight saving time) in early August.

Antares and M4 fit inside the same binocular field of view, with M4 appearing a bit more than 1 degree to the west of Antares. For reference, a typical binocular field has a diameter of 5 to 6 degrees. M4 looks like a rather dim, hazy star in binoculars.

Once you spot it, you might begin longing for a telescope to be able to resolve this fuzzy cluster into a clump of starry pinpoints.

A star map with stars in black on white showing the constellation Scorpius.
A star chart for Scorpius. Via IAU and Sky & Telescope/ Wikimedia Commons.

History of Messier 4

Swiss astronomer Jean-Philippe Loys de Chéseaux discovered M4 in 1746. However, it’s named after comet hunter Charles Messier (1730-1817). He listed M4 as object #4 in his famous Messier catalog. The catalog listed over 100 deep-sky objects that look like comets but really aren’t. Charles Messier wanted to steer comet hunters away from these faint fuzzies that masquerade as comets.

18th century man in white wig and lacy shirt.
Charles Messier (1730-1817), a French astronomer, compiled the Messier catalog of deep sky objects. Image via Wikipedia (public domain).

The science of M4

Today, we know that M4 is a globular star cluster. It’s a globe-shape stellar city packed with perhaps a hundred thousand stars. At about 5,500 light-years from Earth, M4 is the closest globular cluster to us. In comparison, most globulars in our galaxy reside tens of thousands of light-years away. The farthest globular cluster, M54, is about 87,000 light-years in distance.

Unlike open star clusters – such as the Pleiades and the Hyades – the Milky Way galaxy’s 150 or so known globular star clusters are not part of the galactic disk. Instead, globular clusters populate the galactic halo, the sphere-shaped region of the Milky Way circling above and below the galactic disk. There are likely more globular clusters hidden from view by the Milky Way’s central bulge and by clouds of dust and gas.

Difference between globular and open clusters

Globular clusters are tightly packed with tens to hundreds of thousands of stars, whereas open clusters are loosely-bound stellar groups with only a few hundred to a thousand stars. Globular clusters contain primitive stars that are billions of years old, and often almost as old as the universe itself. On the other hand, open clusters consist of young, hot stars that tend to disperse after hundreds of millions of years.

If you had a telescope like Hubble, it would allow you to see these ancient stars as shown in this animation.

M4’s position is at Right Ascension: 16h 23m 35s; Declination: -26° 31′ 33″

A circular scattering of very many brilliant, colorful stars in black space, less dense toward the edges.
A Hubble Space Telescope image of the globular star cluster Messier 4. The cluster is a dense collection of several hundred thousand stars. Astronomers suspect that an intermediate-mass black hole, weighing as much as 800 times the mass of our sun, lurks unseen at its core. Image via ESA/ Hubble/ NASA.

Bottom line: Find M4, one of the easiest globular star clusters for beginners to spot. It’s located just next to reddish Antares, the brightest star in Scorpius the Scorpion.

The post Find M4: An easy to spot globular cluster near Antares first appeared on EarthSky.



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Star chart: Scorpius, a J-shaped constellation, with some stars labeled, on a blue background.
This chart shows the constellation Scorpius the Scorpion, holding the red star Antares at the its heart. Antares will lead you to a great globular cluster called Messier 4 (M4). It’s visible in the evenings for the next few months. Chart via EarthSky.

Bright red star Antares is easy to find in the prominent zodiacal constellation Scorpius the Scorpion. And if you look just slightly west of it through binoculars, you’ll see a small faint diffuse ball of light. Through a moderate-sized telescope, that fuzzy ball resolves into a tight collection of faint stars suspended in the darkness. That’s Messier 4, called M4 for short.

M4 is a globular star cluster. These balls of stars are some of the most ancient parts of our Milky Way galaxy.

M4 shines at magnitude +5.9, so it might just be visible to the unaided eye as a faint smudge on the sky under very dark skies.

Antares shines bright among a backdrop of stars, with M4 nearby, seen as a small compact grouping of many faint stars.
Astronomer and photographer Fred Espenak captured this image of Messier 4, with Antares to its left, using a small telescope. Image via Fred Espenak. Used with permission.

Find M4 in binoculars first

If you’ve never found a deep-sky object on your own before, M4 is a great place to start. Northern Hemisphere summer evenings – or Southern Hemisphere winter evenings – are your best bet for catching M4. It’s easy to find, because it’s right next to the first-magnitude star Antares, the brightest star in the constellation Scorpius the Scorpion.

In early June, Antares is highest in the sky around midnight your local time (1 a.m. daylight saving time). That means it’s high in the south for Northern Hemisphere viewers, and overhead for Southern Hemisphere viewers. The stars return to the same place in the sky some two hours earlier every month. So, Antares is highest up around 10 p.m. (11 p.m. daylight saving time) in early July, and 8 p.m. (9 p.m. daylight saving time) in early August.

Antares and M4 fit inside the same binocular field of view, with M4 appearing a bit more than 1 degree to the west of Antares. For reference, a typical binocular field has a diameter of 5 to 6 degrees. M4 looks like a rather dim, hazy star in binoculars.

Once you spot it, you might begin longing for a telescope to be able to resolve this fuzzy cluster into a clump of starry pinpoints.

A star map with stars in black on white showing the constellation Scorpius.
A star chart for Scorpius. Via IAU and Sky & Telescope/ Wikimedia Commons.

History of Messier 4

Swiss astronomer Jean-Philippe Loys de Chéseaux discovered M4 in 1746. However, it’s named after comet hunter Charles Messier (1730-1817). He listed M4 as object #4 in his famous Messier catalog. The catalog listed over 100 deep-sky objects that look like comets but really aren’t. Charles Messier wanted to steer comet hunters away from these faint fuzzies that masquerade as comets.

18th century man in white wig and lacy shirt.
Charles Messier (1730-1817), a French astronomer, compiled the Messier catalog of deep sky objects. Image via Wikipedia (public domain).

The science of M4

Today, we know that M4 is a globular star cluster. It’s a globe-shape stellar city packed with perhaps a hundred thousand stars. At about 5,500 light-years from Earth, M4 is the closest globular cluster to us. In comparison, most globulars in our galaxy reside tens of thousands of light-years away. The farthest globular cluster, M54, is about 87,000 light-years in distance.

Unlike open star clusters – such as the Pleiades and the Hyades – the Milky Way galaxy’s 150 or so known globular star clusters are not part of the galactic disk. Instead, globular clusters populate the galactic halo, the sphere-shaped region of the Milky Way circling above and below the galactic disk. There are likely more globular clusters hidden from view by the Milky Way’s central bulge and by clouds of dust and gas.

Difference between globular and open clusters

Globular clusters are tightly packed with tens to hundreds of thousands of stars, whereas open clusters are loosely-bound stellar groups with only a few hundred to a thousand stars. Globular clusters contain primitive stars that are billions of years old, and often almost as old as the universe itself. On the other hand, open clusters consist of young, hot stars that tend to disperse after hundreds of millions of years.

If you had a telescope like Hubble, it would allow you to see these ancient stars as shown in this animation.

M4’s position is at Right Ascension: 16h 23m 35s; Declination: -26° 31′ 33″

A circular scattering of very many brilliant, colorful stars in black space, less dense toward the edges.
A Hubble Space Telescope image of the globular star cluster Messier 4. The cluster is a dense collection of several hundred thousand stars. Astronomers suspect that an intermediate-mass black hole, weighing as much as 800 times the mass of our sun, lurks unseen at its core. Image via ESA/ Hubble/ NASA.

Bottom line: Find M4, one of the easiest globular star clusters for beginners to spot. It’s located just next to reddish Antares, the brightest star in Scorpius the Scorpion.

The post Find M4: An easy to spot globular cluster near Antares first appeared on EarthSky.



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