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Fastest star in the galaxy could unlock black hole secrets

This video shows the fastest star in the galaxy, S301, as it orbits the supermassive black hole at the center of the Milky Way galaxy. When closest to the black hole (named Sagittarius A*), the star moves at more than 8% the speed of light. Astronomers are hoping to see the influence of the warped space-time around the black hole on the star’s orbit. This would reveal, for the 1st time, the spin of the black hole. Video via ESO.

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Fastest star in the galaxy could unlock black hole secrets

Astronomers have discovered the fastest star in the Milky Way galaxy. They call it S301, and it moves at more than 8% the speed of light, or 56 million miles per hour (25,000 km/s), as it orbits the central supermassive black hole in our galaxy.

But the real triumph in discovering this star, the European Southern Observatory said on August 19, 2026, is that it can unlock the mystery of our central black hole’s spin.

S301 is the closest star to the Milky Way’s black hole that astronomers have yet discovered. It lies just 12 Earth-sun distances (12 AU) from the mammoth gravity well. Co-author Reinhard Genzel of the Max Planck Institute for Extraterrestrial Physics in Germany said:

Decades carefully tracking stars orbiting our galaxy’s central black hole, Sagittarius A*, have led to this breakthrough discovery of a very promising star. Because it orbits so close to Sagittarius A*, S301 opens a new window to the fundamental properties of spacetime in this extreme black-hole environment.

The researchers published their peer-reviewed study on August 19, 2026, in the journal Nature.

Speeding through a warped space-time environment

S301 has an elliptical (oval-shaped) orbit, so it’s not always 12 AU from our supermassive black hole, Sagittarius A*. That is the closest it gets in its orbit. But the orbit is speedy, whipping around the black hole once every 8.7 years.

Astronomers have already found data from the Very Large Telescope Interferometer to reveal one orbit of the swift star around the black hole. They hope to get even better data for a second orbit once the Extremely Large Telescope comes online around 2030.

S301 gets so close to Sagittarius A* in its orbit that astronomers think it could be affected by the rotating black hole. This rotation is something astronomers have been itching to measure.

According to Einstein’s theory of general relativity, a massive object such as Sagittarius A* will warp the space-time around it. So, astronomers are hoping that when S301 is at its closest to the supermassive black hole, they’ll be able to detect the warp of space-time in the speedy star’s orbit. That would help them measure the spin of the black hole for the first time. Co-author Felix Mang of MPE said:

With this star we hope to measure, within the next 10 years, the spin of the black hole. That would be a dream come true.

Fastest star in the galaxy: 4 panels showing dots with one on an elliptical orbit around a bright dot near bottom. — These are images from the GRAVITY instrument at ESO’s Very Large Telescope Interferometer (VLTI). The bright dot near bottom left is the supermassive black hole at the center of our galaxy, Sagittarius A*. The other dots are stars circling the black hole. The solid line is the path S301 has already completed. And the dimmer, dashed line marks the path it will follow next. Image via ESO/ Gravity Collaboration.

How did the star get so close?

S301 is the closest star we know of to the Milky Way’s central black hole. Mang said:

What is special about this star is that it’s orbiting Sagittarius A* on a very tight orbit, taking just 8.7 years to complete it, and is approaching the black hole at a mere 12 times the distance of Earth to the sun. That is unprecedented.

So how did this star get so unprecedentedly close to the black hole? It couldn’t have formed there, because the gravitational tugs from the black hole wouldn’t have allowed any clouds of gas and dust to coalesce into stars. Therefore, astronomers think the star migrated there. They say it was likely after this star and its binary pair felt the tidal yank of the supermassive black hole. One got flung away from the black hole, while the other was pulled toward it.

That’s fortunate for us, because now – thanks to a speedy star with a short orbit – astronomers can continue to unlock the mysteries of Sagittarius A* and help bolster Einstein’s general theory of relativity. Co-author Juan Osorno of LIRA Observatoire de Paris–PSL, France, said:

For the first time, we would actually be able to measure very directly the spin of a massive black hole, which would be a key test of Einstein’s theory. Without this star, we would need to measure the motion of other stars for several more decades to get anywhere close to measuring the spin of the black hole.

Watch the black hole pull in the fastest star

This animation shows how the fastest known star – S301 – likely came to orbit the supermassive black hole so closely. Initially, the 2 stars orbit each other. But as they near the black hole, the tidal forces pull S301 in, while yeeting the other star into a new neighborhood. Video via ESO/ L. Calçada, M. Kornmesser.

Bottom line: Astronomers have discovered the fastest star in the galaxy. It’s orbiting the supermassive black hole at the center of our galaxy, and it could reveal the black hole’s spin.

Source: Discovery of a star sensitive to the spin of Sagittarius A*

Via ESO

The post Fastest star in the galaxy could unlock black hole secrets first appeared on EarthSky.

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You deserve a daily dose of good news. For the latest in science and the night sky, click here to subscribe to our free daily newsletter.

Fastest star in the galaxy could unlock black hole secrets

But the real triumph in discovering this star, the European Southern Observatory said on August 19, 2026, is that it can unlock the mystery of our central black hole’s spin.

Decades carefully tracking stars orbiting our galaxy’s central black hole, Sagittarius A*, have led to this breakthrough discovery of a very promising star. Because it orbits so close to Sagittarius A*, S301 opens a new window to the fundamental properties of spacetime in this extreme black-hole environment.

The researchers published their peer-reviewed study on August 19, 2026, in the journal Nature.

Speeding through a warped space-time environment

S301 gets so close to Sagittarius A* in its orbit that astronomers think it could be affected by the rotating black hole. This rotation is something astronomers have been itching to measure.

With this star we hope to measure, within the next 10 years, the spin of the black hole. That would be a dream come true.

How did the star get so close?

S301 is the closest star we know of to the Milky Way’s central black hole. Mang said:

What is special about this star is that it’s orbiting Sagittarius A* on a very tight orbit, taking just 8.7 years to complete it, and is approaching the black hole at a mere 12 times the distance of Earth to the sun. That is unprecedented.

For the first time, we would actually be able to measure very directly the spin of a massive black hole, which would be a key test of Einstein’s theory. Without this star, we would need to measure the motion of other stars for several more decades to get anywhere close to measuring the spin of the black hole.

Watch the black hole pull in the fastest star

Bottom line: Astronomers have discovered the fastest star in the galaxy. It’s orbiting the supermassive black hole at the center of our galaxy, and it could reveal the black hole’s spin.

Source: Discovery of a star sensitive to the spin of Sagittarius A*

Via ESO

The post Fastest star in the galaxy could unlock black hole secrets first appeared on EarthSky.

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The Winter Circle: Catch in the morning before dawn

Chart with white dots for stars and blue lines for the Winter Circle. — Although it’s summer in the Northern Hemisphere, a clear sign of winter now looms large in the morning sky. Look for the Winter Circle before dawn in the sunrise direction. Chart via EarthSky.

Summer will soon be ending for us in the Northern Hemisphere. Although it’s still hot outside across much of northern Earth, our days are rapidly shortening now and our nights are getting longer. Meanwhile, a classic sign of winter looms large now in the predawn sky, as it does every year at this time.

The Winter Circle – also called the Winter Hexagon – is not a constellation. Instead, it’s an asterism, or recognizable pattern of stars. It consists of six stars in six different constellations. They are all associated with the winter sky for those in the Northern Hemisphere (summer sky for the Southern Hemisphere).

Winter Circle’s 6 (or 7) bright stars

Beloved constellation Orion the Hunter is in the southwest portion of the Winter Circle (lower right on our chart above). If you’ve never seen the Winter Circle but are acquainted with Orion, this constellation presents a great jumping off place for identifying these stars. And it presents a great size comparison too. Orion is big, but the Winter Circle is much bigger!

So look at our chart above and notice the star Rigel in Orion. Then start moving around the Circle clockwise. You’ll encounter Sirius in the constellation Canis Major the Greater Dog, Procyon in the constellation Canis Minor the Smaller Dog, Pollux (and Castor) in the constellation Gemini the Twins, Capella in the constellation Auriga the charioteer and Aldebaran in the constellation Taurus the Bull. Nearly all of the Winter Circle stars are 1st-magnitude stars. And that means they’re bright and easy to see.

The exception is the star Castor in Gemini. It’s not a 1st-magnitude star and not as bright as the other stars in the Winter Circle. But it’s pretty bright! In fact, it’s the sky’s brightest 2nd-magnitude star. If you include Castor as a Winter Circle star, then there are seven stars in the Circle.

When to see the Winter Circle

We don’t see the Winter Circle in June and July because it’s lost in the glare of the sun. However, in late August, the Winter Circle returns to the morning sky. And months from now, when we’re into the Northern Hemisphere’s winter, we’ll see the Winter Circle in the evening sky.

Annotated image of stars with the Winter Hexagon outlined. — View at EarthSky Community Photos. | Amit Raka| submitted this image on January 25, 2025, and wrote: “We gazed upon a breathtaking celestial wonder: the Winter Circle, also known as the Winter Hexagon. This image showcases the brilliance of 6 of the brightest stars forming a giant hexagonal asterism in the winter night sky. The view was truly mesmerizing, leaving all in awe as they admired the countless stars and even spotted planets twinkling amidst the vast cosmic expanse.” Thank you, Amit!

Night sky scene with hexagon and figures of constellation superimposed over top stars. — View at EarthSky Community Photos. | Jose Zarcos Palma in Mina São Domingo, Mertola, Portugal, took this image of the winter hexagon on December 26, 2022. Jose wrote: “I planned this composition to catch the great Winter Circle in an early stage of its ascension. We can clearly see Sirius in Canis Major the Greater Dog near the chimney on the right side. It’s just below Orion the Hunter. On top of the image, the planet Mars is near Aldebaran in Taurus the Bull.” Thank you, Jose!

Bottom line: The Winter Circle – or Winter Hexagon – is back in the morning sky. Check it out before dawn. It’s made up of some of our brightest stars from several constellations.

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Winter Circle’s 6 (or 7) bright stars

When to see the Winter Circle

Bottom line: The Winter Circle – or Winter Hexagon – is back in the morning sky. Check it out before dawn. It’s made up of some of our brightest stars from several constellations.

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Delphinus the Dolphin has a graceful kite shape

A starfield, with the shape of the dolphin outlined. — Photo of the constellation Delphinus with annotations from IAU and Sky & Telescope. Here is the non-annotated version. Image via E. Slawik/ NOIRLab/ NSF/ AURA/ M. Zamani.

How to see Delphinus

Delphinus the Dolphin is the 69th-largest of the 88 constellations. It comes into view each year on northern summer evenings. And by northern fall, it’s well placed for viewing, arcing high across the sky each night. But its stars are faint. So to see it, you’ll want a dark sky.

Delphinus lies just outside of the line connecting the stars Deneb in Cygnus the Swan and Altair in Aquila the Eagle. These bright stars form two corners of the famous asterism called the Summer Triangle.

Scan along that line with your eye or binoculars. And if your sky is dark enough, Delphinus will pop into view.

Delphinus’ shape is suggestive of the animal it’s supposed to represent (this is not always the case with constellations, as you might have noticed). Indeed, its faint stars form a kite shape with a tail. The little dolphin appears to leap out of the dark waters of the night sky!

Star chart: Summer Triangle outlined with its apex stars labeled and 3 small constellations near it. — The famous Summer Triangle is now in the evening sky. Once you know it, you can use it to star-hop to several small constellations in or near the Triangle: Delphinus the Dolphin, Sagitta the Arrow and Vulpecula the Fox. Just be sure you’re looking in a dark sky! Chart via EarthSky.

Star chart of constellation Delphinus with 5 stars, 3 labeled. — A closeup on the constellation Delphinus the Dolphin and 3 of its named stars. Chart via EarthSky.

The stars of the Dolphin

The brightest star in the Dolphin is Beta Delphini, which shines at magnitude 3.6. The star also goes by the name Rotanev. Lying 101 light-years from Earth, it marks the point in the constellation where the Dolphin’s body connects with its tail.

The second brightest star is Alpha Delphini, at magnitude 3.7. This star’s nickname is Sualocin. Lying 254 light-years away, it marks the back of the Dolphin.

By the way, these two stars’ common names, Rotanev and Sualocin, are part of a puzzle. Italian astronomer Nicolaus Venator named these two stars. Can you solve the puzzle? Hint: try reading the stars’ names backward.

The nose of Delphinus is Gamma Delphini, a double star. The pair of stars shine at magnitude 4.2 and 5.1. They lie approximately 101 light-years away.

The belly of the dolphin is Delta Delphini, a magnitude 4.4 star lying 223 light-years away.

And although Delphinus is a small constellation, it contains an asterism: Job’s Coffin. The four stars that mark the body of the Dolphin are the same stars that form Job’s Coffin.

The tail of the dolphin contains one star, Epsilon Delphini or Aldulfin. The magnitude-4.0 star lies 330 light-years away.

In 2013, a bright nova exploded in Delphinus not far from Sualocin. The nova, V339 Delphini, was temporarily visible to the unaided eye.

Star field with labeled objects, and small bright dot circled in blue and labeled Nova. — This image of the night sky shows the region of Delphinus and the Summer Triangle where nova V339 briefly lit up in 2013. Image via NASA/ Wikimedia Commons.

Deep-sky objects

Most of the deep-sky objects in Delphinus are quite dim. The brightest of these is NGC 6934, a globular cluster found about 4 degrees out from the tail. NGC 6934 shines at magnitude 8.9. Another globular cluster, NGC 7006, lies off the nose of the Dolphin. And if you draw a line from Sualocin through the nose star Gamma and extend it for about twice that distance, you’ll reach NGC 7006. NGC 7006 shines at magnitude 10.6.

Two planetary nebulae lie within the northwestern boundary of the constellation. Both shine with a magnitude of 12. NGC 6905 – the Blue Flash Nebula – lies directly above the Dolphin’s back. The other planetary nebula – NGC 6891 – is above Delphinus’ tail. A number of galaxies are scattered about Delphinus; however, most of them are 12th magnitude and dimmer, making them very hard to spot without a large telescope.

Small, hazy light blue blob with barely perceptible features, in starfield. — The Blue Flash Nebula, NGC 6905, lies above the back of Delphinus the Dolphin. Image via Digital Sky Survey 2/ In-the-Sky.org/ Dominic Ford. Used with permission.

Delphinus and a neutrino

In 2021, scientists announced they’d pinpointed the origin of a neutrino, or high-energy particle. And it came from the direction of Delphinus the Dolphin.

They believe that, in a cataclysmic event, a supermassive black hole and a star drew too close together. The black hole shredded the star, which released the cosmic ray neutrino. Scientists detected the neutrino using the IceCube Neutrino Observatory at the Amundsen-Scott South Pole Station in Antarctica. So much info from such a tiny particle! Read more about the discovery.

Star chart with black stars on white of constellation Delphinus showing the outline and labels on the stars. — Star chart of the constellation Delphinus. Image by IAU/ Wikipedia.

Delphinus in history and mythology

The name Delphinus means dolphin in Latin. But it was a Greek astronomer – Ptolemy of Alexandria in the second century CE – who first cataloged these stars. In Greek mythology, Delphinus represents the dolphin sent by the sea god Poseidon to fetch Amphitrite, a goddess of the sea and one of the fabled Nereids. It’s said Poseidon chose Amphitrite from among her sisters as they performed a dance on the isle of Naxos. The dolphin carried Amphitrite to Poseidon, and she became his wife. He rewarded the dolphin by making it a constellation.

And in another story, Delphinus saves the Greek poet Arion when he is attacked by robbers on a ship. They were about to kill Arion, but he begged permission to sing a final song. His captors agreed, and the poet stood on the deck of the ship and sang a dirge accompanied by his lyre. He then threw himself overboard. A dolphin who’d heard his song and been charmed by the music saved him.

Antique colored etching of an ugly fish next to a flying eagle, all scattered with stars. — In this drawing from Urania’s Mirror, Delphinus the Dolphin is the green sea creature at left. Image via Wikipedia.

Bottom line: Delphinus the Dolphin is a tiny constellation that looks like the animal it’s supposed to represent. Look for the Dolphin leaping near the Summer Triangle.

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How to see Delphinus

Scan along that line with your eye or binoculars. And if your sky is dark enough, Delphinus will pop into view.

The stars of the Dolphin

The second brightest star is Alpha Delphini, at magnitude 3.7. This star’s nickname is Sualocin. Lying 254 light-years away, it marks the back of the Dolphin.

The nose of Delphinus is Gamma Delphini, a double star. The pair of stars shine at magnitude 4.2 and 5.1. They lie approximately 101 light-years away.

The belly of the dolphin is Delta Delphini, a magnitude 4.4 star lying 223 light-years away.

And although Delphinus is a small constellation, it contains an asterism: Job’s Coffin. The four stars that mark the body of the Dolphin are the same stars that form Job’s Coffin.

The tail of the dolphin contains one star, Epsilon Delphini or Aldulfin. The magnitude-4.0 star lies 330 light-years away.

In 2013, a bright nova exploded in Delphinus not far from Sualocin. The nova, V339 Delphini, was temporarily visible to the unaided eye.

Deep-sky objects

Delphinus and a neutrino

In 2021, scientists announced they’d pinpointed the origin of a neutrino, or high-energy particle. And it came from the direction of Delphinus the Dolphin.

Delphinus in history and mythology

Bottom line: Delphinus the Dolphin is a tiny constellation that looks like the animal it’s supposed to represent. Look for the Dolphin leaping near the Summer Triangle.

Don’t miss the next unmissable night sky event. Sign up to our free newsletter for daily night sky updates, as well as the latest science news.

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Could there be life in helium atmospheres on exoplanets?

Life in helium atmospheres: Greenish planet with whitish bands in its atmosphere and its sun in the distance. — View larger. | Artist’s concept of an exoplanet with a helium-dominated atmosphere. A new study suggests that there could be life in helium atmospheres on rocky exoplanets. Image via NASA/ JPL-Caltech.

Could life exist on exoplanets with helium atmospheres? A new study suggests it’s possible.
Experiments showed that helium-dominated atmospheres would be non-toxic to many types of earthly lifeforms.
Helium atmospheres could also preserve other gases associated with life, making them easier to detect by astronomers.

Science news, night sky events and beautiful photos, all in one place. Click here to subscribe to our free daily newsletter.

Life in helium atmospheres on exoplanets?

When searching for possible signs of alien life on exoplanets, scientists tend to focus on atmospheres that might be earthlike. That is, atmospheres dominated by nitrogen, oxygen or even carbon dioxide. But there’s another possibility that has been largely overlooked. What about helium atmospheres?

Helium is the second-most abundant element in the universe. And we know there are exoplanets with helium in their atmospheres.

A new paper just released from researchers at Massachusetts Institute of Technology (MIT) in the U.S. and Wroclaw University of Science and Technology and JJ Scientific in Poland, examines the possibility of life existing in helium atmospheres. Intriguingly, the researchers found that there are no intrinsic barriers that would prevent life as we know it from being able to survive in a helium-dominated atmosphere.

The new study looks at a largely overlooked body of laboratory research on life in helium-dominated atmospheres. And the results are surprising.

The researchers published their preprint version of the paper (not yet peer-reviewed) on August 16, 2026, on arXiv.

An overlooked possibility

Scientists had largely ignored the idea that planets with helium atmospheres could support life. This was based on two key assumptions.

The first was that helium is expected to typically escape from the atmospheres of rocky planets, along with hydrogen. The second is that Earth itself doesn’t have much helium in its atmosphere. So those were the models scientists had to work with.

But the research team decided to take a closer look at the possibility of life on helium worlds. So they synthesized helium-dominated atmospheres in the laboratory. And a wide variety of organisms were subjected to that environment. These included bacteria, fungi, protozoa, microalgae, plants and animals. The results were surprising.

When the organisms had the essential metabolic requirements – the chemical processes in your body that change food into energy and build or repair cells – then they were able to tolerate and survive in the helium atmosphere.

No barriers to life

Overall, the helium did not present any barriers to life. In fact, there was no demonstrated toxicity and no fundamental barrier to metabolism, cell division, photosynthesis, nitrogen fixation or coordinated multicellular activity, including in humans. This suggests that life could survive and even thrive on planets with helium atmospheres.

And it’s seemingly because helium is chemically inert. Whether or not it would actually help life flourish is another question. But it won’t hamper or destroy it.

This is also good news for scientists trying to detect signs of life in helium atmospheres. The helium won’t destroy any biosignature gases present in the atmosphere. And it won’t obscure their spectral signatures. In fact, helium-dominated atmospheres also have low mean molecular weights and large scale heights. This actually strengthens spectral features in transmission and improves remote detectability.

Helium could help scientists find alien life

Not only does this show alien life could exist in a helium atmosphere, it could help scientists actually find it. As the paper concludes:

The possibility of helium-dominated, temperate exoplanet atmospheres asks us to widen a familiar assumption: that life-bearing atmospheres must resemble Earth’s in their bulk composition. Helium contributes little chemistry of its own, yet that very inertness allows the gases required by life to coexist within a stable atmospheric envelope, while its low molecular weight may make their spectral signatures unusually accessible.

The fact that such diverse forms of life can survive, metabolize and reproduce under helium-dominated conditions supports the inclusion of helium-dominated exoplanets among the targets in the search for life beyond Earth.

The convergence of atmospheric-evolution models, the first observations of helium around a habitable-zone rocky planet and decades of laboratory evidence establishes that helium is not an exotic obstacle to life and might in fact enable the first biosignature gas detection on a rocky world in our galaxy.

Planet with a reddish haze around it. Its sun and another planet in the distance. — Last month, researchers reported detecting helium escaping from exoplanet LHS 1140 b. That means it must have an atmosphere, but scientists don’t yet know what other gases are in it. This is an artist’s concept of the planet in question. Image via Melissa Weiss/ CfA.

Leaking helium reveals atmosphere on rocky exoplanet

Last month, scientists found the first strong evidence for an atmosphere on a rocky planet in the habitable zone of its star. The planet, LHS 1140 b, is a super-Earth exoplanet 48 light-years away. It orbits a red dwarf star.

Scientists detected helium leaking from this world. The leaking helium means the planet must have an atmosphere. But scientists don’t know yet what the other gases are in that atmosphere.

In 2018, astronomers reported finding an exoplanet – HAT-P-11b – whose helium atmosphere is extended or puffed out, kind of like a child’s balloon.

Bottom line: Is life in helium atmospheres on exoplanets possible? A new study says that there are no barriers to life on worlds with helium-dominated atmospheres.

Source: The Viability of Life in Helium-Dominated Exoplanet Atmospheres

Via Astrobiology

The post Could there be life in helium atmospheres on exoplanets? first appeared on EarthSky.

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Could life exist on exoplanets with helium atmospheres? A new study suggests it’s possible.
Experiments showed that helium-dominated atmospheres would be non-toxic to many types of earthly lifeforms.
Helium atmospheres could also preserve other gases associated with life, making them easier to detect by astronomers.

Science news, night sky events and beautiful photos, all in one place. Click here to subscribe to our free daily newsletter.

Life in helium atmospheres on exoplanets?

Helium is the second-most abundant element in the universe. And we know there are exoplanets with helium in their atmospheres.

The new study looks at a largely overlooked body of laboratory research on life in helium-dominated atmospheres. And the results are surprising.

The researchers published their preprint version of the paper (not yet peer-reviewed) on August 16, 2026, on arXiv.

An overlooked possibility

Scientists had largely ignored the idea that planets with helium atmospheres could support life. This was based on two key assumptions.

No barriers to life

And it’s seemingly because helium is chemically inert. Whether or not it would actually help life flourish is another question. But it won’t hamper or destroy it.

Helium could help scientists find alien life

Not only does this show alien life could exist in a helium atmosphere, it could help scientists actually find it. As the paper concludes:

The possibility of helium-dominated, temperate exoplanet atmospheres asks us to widen a familiar assumption: that life-bearing atmospheres must resemble Earth’s in their bulk composition. Helium contributes little chemistry of its own, yet that very inertness allows the gases required by life to coexist within a stable atmospheric envelope, while its low molecular weight may make their spectral signatures unusually accessible.

The fact that such diverse forms of life can survive, metabolize and reproduce under helium-dominated conditions supports the inclusion of helium-dominated exoplanets among the targets in the search for life beyond Earth.

The convergence of atmospheric-evolution models, the first observations of helium around a habitable-zone rocky planet and decades of laboratory evidence establishes that helium is not an exotic obstacle to life and might in fact enable the first biosignature gas detection on a rocky world in our galaxy.

Leaking helium reveals atmosphere on rocky exoplanet

Scientists detected helium leaking from this world. The leaking helium means the planet must have an atmosphere. But scientists don’t know yet what the other gases are in that atmosphere.

In 2018, astronomers reported finding an exoplanet – HAT-P-11b – whose helium atmosphere is extended or puffed out, kind of like a child’s balloon.

Bottom line: Is life in helium atmospheres on exoplanets possible? A new study says that there are no barriers to life on worlds with helium-dominated atmospheres.

Source: The Viability of Life in Helium-Dominated Exoplanet Atmospheres

Via Astrobiology

The post Could there be life in helium atmospheres on exoplanets? first appeared on EarthSky.

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National parks from space: How many can you name?

National parks from space: Water surrounding land on three sides with a chain of keys and lines for a city at right. — (1) The Landsat 8 satellite captured this view of a national park from space. The southern part of the state you see here is dominated by a *River of Grass*, the only place in the world where alligators and crocodiles coexist. Can you name this national park? Then read on to see how many more national parks from space you can name. All images this page via NASA Earth Observatory.

How many national parks from space can you name?

It’s National Park Week! In 2026, we celebrate the US national parks from August 22 to 30. And in honor of what has been called America’s best idea, we at EarthSky are challenging you to see how many parks you can identify from space.

America’s national parks look spectacular from the ground. But from hundreds of miles above Earth, they take on an entirely different appearance. Rivers become thin threads, mountains reveal their enormous scale and some of the landscapes we recognize instantly from photographs become surprisingly difficult to identify.

The national park image above is one that might be easy to recognize. You can see the curve of southern Florida, with Miami and its suburbs to the east and the start of the keys to the south. The green wetlands that dominate the southern portion of the state, where crocodiles mix with alligators, has been nicknamed the River of Grass. Try your hand at nine more parks below, which we’ve divided up into categories of easy, medium and hard. Good luck!

Easy: New visitor category

Green land with many islands and blue water off to the right and below. — (2) Nearly half of this national park on the East Coast consists of Mount Desert Island, which has a dual-lobed shape as seen from above. And on this island you’ll find Cadillac Mountain, which is the first place to see sunrise in the continental U.S. during the winter months. Can you name this park?

A landmass on the right with a handful of islands offshore surrounded by dark water. — (3) This national park might sit just offshore from one of the most populous areas in the U.S., yet its isolation gives it the nickname of *Galapagos of North America*. Half the park is underwater, including giant kelp forests. Meanwhile, on land you’ll find more than 145 plant and animal species found nowhere else on Earth, including the inquisitive island fox. Can you name this park?

Brown and green land with 3 plumes of smoke and a deep blue ocean at the bottom. — (4) Proximity to water can certainly make it easier to identify a location from space. But in this case, the plumes of smoke and dark black substance running toward the sea should help you solve the mystery. The activity here is creating some of the newest earth on … well, Earth! Can you name this park?

Medium: Backpacker category

A large blue lake with a volcanic-looking mountain inside and some white scattered around the edges of the water-filled crater. — (5) This national park is centered around a volcano – Mount Mazama – that blew its top some 7,000 years ago. Now, rainwater has filled the space, creating the deepest lake in the U.S. at 1,943 feet. You can still see the cinder cone (partially hidden by clouds here), named Wizard Island, poking through the blue waters. Can you name this park?

A mountain peak covered in snow with many streams coming down the flanks. — (6) This majestic, snow-covered mountain is the source of 5 major rivers. That’s thanks to the 28 named glaciers on its flanks. Though it’s not expected to erupt any time soon, this is an active volcano. Can you name this park?

A deep canyon with many branches colored in reds and tans. — (7) The first clue to solving this puzzle is knowing that often, when viewing satellite photos, depressions can look like bulges and vice versa. Scientists call this the crater-dome illusion. Look closely, and you’ll see that’s not a ridge, but a muddy river that snakes through miles of weathered terrain. Can you name this park?

Hard: Park ranger category

Shades of tan, showing a pointed dark mountain range at center and a snaky river curving along the bottom. — (8) That dark cluster of mountains you see below is the only mountain range in the U.S. completely inside a single national park. This park also contains 450 species of birds, more than any other U.S. national park. Need a hint in identifying it? Trace the river below that outlines part of its border. Can you name this park?

Tan landscape with mountains at lower left and a big area of white in the middle. — (9) The light-colored splotch in the middle of this image shows the largest dunefield of its kind in the world. There are fossilized Ice Age human and animal footprints preserved here. And the life that resides here today can be pale in color to match its surroundings, like the bleached earless lizard. Can you name this park?

View of green landscape with reddish rocks and many steep slopes and some bright blue lakes. — (10) This park contains rocks that are hundreds of millions of years old. The park is also home to Triple Divide Peak, where rain that falls on it can flow either to the Atlantic, Pacific or Arctic Oceans, which has earned the park the nickname *Crown of the Continents*. Its blue and turquoise lakes are due to ground-up rocks that scatter light. Can you name this park?

Answers for the national parks from space quiz

(1) Everglades, via Landsat 8
(2) Acadia, via Landsat 8
(3) Channel Islands, via NOAA-20 satellite
(4) Hawaii Volcanoes, via Earth Observing-1 satellite
(5) Crater Lake, via ISS
(6) Mount Rainier, via ISS
(7) Grand Canyon, via ISS
(8) Big Bend, via Landsat 7
(9) White Sands, via ISS
(10) Glacier, via Ikonos satellite

How did you score?

0-3: Hello, new visitor! Welcome to the national parks.
4-7: Congrats on attaining the level of expert backpacker!
8+: Okay, are you secretly a park ranger?

Bottom line: Take the quiz to see how many national parks from space you can name. And don’t forget to celebrate National Park Week, from August 22 to 30!

The post National parks from space: How many can you name? first appeared on EarthSky.

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How many national parks from space can you name?

Easy: New visitor category

Medium: Backpacker category

Hard: Park ranger category

Answers for the national parks from space quiz

How did you score?

0-3: Hello, new visitor! Welcome to the national parks.
4-7: Congrats on attaining the level of expert backpacker!
8+: Okay, are you secretly a park ranger?

Bottom line: Take the quiz to see how many national parks from space you can name. And don’t forget to celebrate National Park Week, from August 22 to 30!

The post National parks from space: How many can you name? first appeared on EarthSky.

from EarthSky https://ift.tt/oJOYzkN

The return of Sirius in the morning signals seasonal change

Return of Sirius: Morning sky in August with Sirius and constellation Orion above it and stars labeled. — Here’s an early morning sight you won’t want to miss. The return of Sirius and the winter constellations to the morning sky heralds a change of season. Chart via EarthSky.

In late August and early September, look for two hints of the changing season in the predawn sky: Orion the Hunter and Sirius the Dog Star.

Orion is easily recognizable by the short straight line of three bright stars that make up his Belt. The constellation rises before dawn at this time of year. And the sky’s brightest star, Sirius – also known as the Dog Star, in the constellation Canis Major the Greater Dog – follows Orion into the sky as the predawn darkness gives way to dawn.

Have you noticed a very bright, madly twinkling star in this part of the early morning sky? Many do at this time of year. That star is Sirius. It’s so bright that, when it’s low in the sky, it shines with glints of red and flashes of blue. That’s the effect of our thick atmosphere causing its light to twinkle.

You won’t see Orion and Sirius in the evening sky until northern winter (or southern summer). But presently, the Hunter and the Dog Star lord over the sky at dawn.

Stars and constellations pass behind the sun

Orion was low in the west after sunset around March and April. By June of each year, the Hunter lies behind the sun as seen from Earth. Orion only returned to visibility in Earth’s sky about a month ago. Once a constellation becomes visible again, after being behind the sun, it always appears in the east before sunrise.

That’s because – as Earth moves around the sun – all stars rise two hours earlier with each passing month. So Orion is now higher at dawn than it was a month ago.

As seen from the Northern Hemisphere, Orion precedes Sirius into the sky. After Orion first appears at dawn, you can count on Sirius to appear in the morning sky a few weeks later.

Distant mountains under a starry sky, including high Orion and a very bright dot to the left and a bit lower than Orion. — View at EarthSky Community Photos. | Jeremy Evans caught this image on January 22, 2026, in California and wrote: “Orion and Sirius over the Sierra Nevada around midnight. Cold foggy night, temperature was 8 degrees F. Taken from backyard using snowshoes to get to the photo spot.” Note the brightest star at the left is Sirius. Thank you, Jeremy!

The heliacal rising of Sirius

Now will be a good time to look for the heliacal rising of Sirius. In other words, what is the first date that you can see Sirius, with the unaided eye, in your morning sky? It depends on your latitude.

Below are a couple of graphs showing when you can expect to first see Sirius in your eastern predawn sky. They are designed for average eyesight, average weather and from near sea level.

Graph with arcing line of dots, latitude on Y axis and dates across the bottom. — The heliacal rising of Sirius from latitudes 20 degrees south to 70 degrees north. Philadelphia, for example, is at 40 degrees north latitude, so it will see Sirius reappear in the morning sky around August 17. Based on calculations by Culture Diff’. Graph via Don Machholz.

Graph with line of dots arcing up to the right. Date on the x axis and latitude on the y axis. — The heliacal rising of Sirius from north latitudes 10 degrees to 60 degrees. Based on calculations by Culture Diff’. Graph via Don Machholz.

The return of Sirius and the colors of the stars

With Sirius and the stars of Orion low in your sky, you might notice that their light shimmers in various colors. But it’s not the stars that are changing; this is the prismatic effect of Earth’s atmosphere. As seen through a greater-than-usual thickness of atmosphere in the direction of the horizon, the mostly white light of Sirius can be broken up into striking colors on a summer morning.

But stars can be intrinsically colorful, too. Be sure to notice the reddish color of Betelgeuse when you watch Orion rise in these late summer months.

Long, thin green line of a meteor above a beach, with constellation Orion and bright star below it. — View at EarthSky Community Photos. | Daniel Friedman captured this beautiful shot from Montauk, New York, in December 2020. Note how bright Sirius is on the left, and how its color contrasts with the star Betelgeuse in the top left corner. Daniel wrote: “Out on the beach late with no one around for miles. Never captured a bolt like this and have been chasing meteor showers for years and years.” Thank you, Daniel!

Bottom line: A sign of the changing season is the return of Sirius before sunup. Be the first from your latitude to see Sirius in the morning sky.

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In late August and early September, look for two hints of the changing season in the predawn sky: Orion the Hunter and Sirius the Dog Star.

You won’t see Orion and Sirius in the evening sky until northern winter (or southern summer). But presently, the Hunter and the Dog Star lord over the sky at dawn.

Stars and constellations pass behind the sun

That’s because – as Earth moves around the sun – all stars rise two hours earlier with each passing month. So Orion is now higher at dawn than it was a month ago.

As seen from the Northern Hemisphere, Orion precedes Sirius into the sky. After Orion first appears at dawn, you can count on Sirius to appear in the morning sky a few weeks later.

The heliacal rising of Sirius

Below are a couple of graphs showing when you can expect to first see Sirius in your eastern predawn sky. They are designed for average eyesight, average weather and from near sea level.

The return of Sirius and the colors of the stars

But stars can be intrinsically colorful, too. Be sure to notice the reddish color of Betelgeuse when you watch Orion rise in these late summer months.

Bottom line: A sign of the changing season is the return of Sirius before sunup. Be the first from your latitude to see Sirius in the morning sky.

Enjoying EarthSky so far? Sign up for our free daily newsletter today!

Help support EarthSky! Check out the EarthSky store for fun astronomy gifts and tools for all ages!

The post The return of Sirius in the morning signals seasonal change first appeared on EarthSky.

from EarthSky https://ift.tt/bK4C3PA

Nancy Grace Roman Space Telescope launches Sunday!

Distant large white tube at harbor with American flag and a sign for the Nancy Grace Roman telescope. — On June 21, 2026, the Nancy Grace Roman Space Telescope arrived at Florida’s Kennedy Space Center on NASA’s enormous Pegasus barge (left) in preparation for its August 30 launch. Image via Amber Jean Notvest/ NASA.

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The Nancy Grace Roman Space Telescope launches on Sunday

The Nancy Grace Roman Space Telescope is set to launch no earlier than 6:26 a.m. CDT on Sunday, August 30, 2026. The launch will be on a SpaceX Falcon Heavy rocket from Launch Complex 39A at Kennedy Space Center. Amazingly, the space telescope is eight months ahead of schedule!

On June 21, 2026, the Nancy Grace Roman Space Telescope arrived at Kennedy Space Center in Florida ahead of its launch. It completed testing at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, before being loaded on NASA’s Pegasus barge for its shipment to Florida. After additional testing at Kennedy Space Center, the telescope is ready for its journey to L2, or the second sun-Earth Lagrange point.

You may already be familiar with this location because the James Webb Space Telescope is also there, sending back infrared images of the universe. The Roman telescope also has infrared eyes. NASA said:

Roman’s wide field of view and rapid survey capabilities will reveal billions of galaxies, hundreds of thousands of new exoplanets, hundreds of black holes, and will provide vast volumes of daily data for astronomers to study.

The Nancy Grace Roman Space Telescope is complete

NASA said back on December 4, 2025, that the construction of the Nancy Grace Roman Space Telescope was complete. Julie McEnery, Roman’s senior project scientist at NASA Goddard, said:

With Roman’s construction complete, we are poised at the brink of unfathomable scientific discovery. In the mission’s first five years, it’s expected to unveil more than 100,000 distant worlds, hundreds of millions of stars, and billions of galaxies. We stand to learn a tremendous amount of new information about the universe very rapidly after Roman launches.

Two people in white clean suits inside a large building looking up at three enormous solar panels. — The fully assembled Nancy Grace Roman Space Telescope. Image via Jolearra Tshiteya/ NASA.

A graphic showing what the telescope will be looking at and the number of objects it might find. — The Nancy Grace Roman Space Telescope by the numbers. Graphic via NASA/ Goddard Space Flight Center.

Meet the Nancy Grace Roman Space Telescope

Remember what astronomical images were like before we had the Hubble Space Telescope? Hubble was the first large optical telescope to be launched into space, above Earth’s obscuring atmosphere. And it fundamentally changed our view of the cosmos. Astronomers say the Nancy Grace Roman Space Telescope will do that, too, giving us a view of the universe we’ve never had before. The telescope will have a primary mirror of 7.9 feet in diameter (2.4 meters). That’s the same size as Hubble. But a single image from the Nancy Grace Roman Space Telescope will equal the sky coverage of 100 Hubble images.

Scientists expect the telescope to answer fundamental questions about distant planets orbiting stars in our Milky Way galaxy, about the dark energy we haven’t yet detected directly but believe makes up a substantial portion of our cosmos … and about what astronomers call the cosmic dawn.

The telescope’s Wide Field Instrument (WFI), its primary instrument, will have a field of view 100 times greater than Hubble’s infrared instrument. Roman’s large field of view means it can capture more sky in less time. The Wide Field Instrument will scan the Milky Way for exoplanets, or planets orbiting distant stars. Over the past 30 years, since the early 1990s until now, we’ve discovered more than 5,000 exoplanets. The Nancy Grace Roman Space Telescope is expected to increase that number to some 100,000 exoplanets in the next five years.

Roman’s other instrument is the Coronagraph Instrument. The Coronagraph Instrument will perform high-contrast imaging and spectroscopy to gather more knowledge of individual exoplanets. More on the coronagraph below.

Interview with Néstor Espinoza

Watch this 52-second clip of astronomer Néstor Espinoza of the Space Telescope Science Institute talking with EarthSky’s Deborah Byrd. Néstor told us this telescope should increase the number of known exoplanets – or planets orbiting distant suns – from 5,000 now to 100,000 in just 5 years!

The Roman telescope’s 100,000 new exoplanets

The Roman space telescope will survey our galaxy, taking observations every 15 minutes for more than a year. What a mass of data it’ll collect in just that first year! The data will enable astronomers to track the brightness changes in stars, which could lead to discoveries of exoplanets, rogue planets, isolated black holes and more.

So how will the Roman space telescope find its 100,000 exoplanets? With the aid of the Roman Coronagraph, the first high-contrast active wavefront-control coronagraph to fly in space. NASA said:

The Roman Coronagraph will advance scientists’ ability to directly image planets and disks around other stars. Coronagraphs work by blocking light from a bright object, like a star, so that the observer can more easily see a faint object, like a planet [next to the bright object].

The Roman Coronagraph is designed to detect planets 100 million times fainter than their stars, or 100 to 1,000 times better than existing space-based coronagraphs.

The Roman Coronagraph will be capable of directly imaging reflected starlight from a planet akin to Jupiter in size, temperature and distance from its parent star.

Roman space telescope: A bulky, cylindrical, metallic object with solar panels in space. — Artist’s concept of the Nancy Grace Roman Space Telescope. Image via NASA.

The Roman telescope and the cosmic dawn

After the Big Bang that set our universe into motion, the cosmos was dark for some 380,000 to 200 million years. Yes, dark. Even though stars had already begun to shine, neutral atoms would absorb their light, leaving the cosmos in a kind of obscuring fog. Then neutral atoms began to break apart, and the fog began to lift. The light of stars broke through and began traveling throughout space. Astronomers call this transition from dark to light the cosmic dawn. Takahiro Morishita of Caltech said:

Roman will excel at finding the building blocks of cosmic structures like galaxy clusters that later form. It will quickly identify the densest regions, where more ‘fog’ is being cleared, making Roman a key mission to probe early galaxy evolution and the cosmic dawn.

Roman’s wide field of view will help determine how common quasars are and whether certain types of galaxies played a larger role in clearing the fog. It will also look for “cosmic daybreakers” that illuminated our universe.

Many wispy, swirly, purplish bubbles filled with clusters of stars in black space. — Artist’s concept of the cosmic dawn. This is how the universe may have looked at less than a billion years old. Image via NASA/ ESA/ A. Schaller (for STScI).

The Roman space telescope and dark energy

Dark energy is a mysterious force that makes up about 68% of the total energy content of our universe. Dark energy is responsible for the acceleration of our expanding universe. Roman will help astronomers understand just what dark energy is by taking a closer look at how the universe has evolved. Roman’s wide field will allow us a bigger picture of the universe. Mapping the distribution of matter and measuring distant supernovae will help show how dark energy might have changed over time.

Graphic showing a plot with a swoosh-shaped curve and an inset with galaxies connected by a blue abstract net. — In the universe’s past, expansion occurred at a slower rate than we see in our universe today. Dark energy is behind the accelerated expansion. Image via NASA Scientific Visualization Studio.

Who was Nancy Grace Roman?

Nancy Grace Roman has the honorary title of Mother of the Hubble Space Telescope. Born in 1925, Roman became one of the few female astronomers in a male-dominated science. Among other accomplishments, she became the first female executive at NASA and NASA’s first Chief of Astronomy. She earned her nickname by helping get the Hubble Space Telescope approved by Congress. Roman was most excited for Hubble’s discoveries on dark energy. The telescope that will now bear Roman’s name will increase our understanding of dark energy, the universe and our place in it.

The Nancy Grace Roman Space Telescope launches on Sunday

Roman’s wide field of view and rapid survey capabilities will reveal billions of galaxies, hundreds of thousands of new exoplanets, hundreds of black holes, and will provide vast volumes of daily data for astronomers to study.

The Nancy Grace Roman Space Telescope is complete

NASA said back on December 4, 2025, that the construction of the Nancy Grace Roman Space Telescope was complete. Julie McEnery, Roman’s senior project scientist at NASA Goddard, said:

With Roman’s construction complete, we are poised at the brink of unfathomable scientific discovery. In the mission’s first five years, it’s expected to unveil more than 100,000 distant worlds, hundreds of millions of stars, and billions of galaxies. We stand to learn a tremendous amount of new information about the universe very rapidly after Roman launches.

Meet the Nancy Grace Roman Space Telescope

Interview with Néstor Espinoza

The Roman telescope’s 100,000 new exoplanets

So how will the Roman space telescope find its 100,000 exoplanets? With the aid of the Roman Coronagraph, the first high-contrast active wavefront-control coronagraph to fly in space. NASA said:

The Roman Coronagraph will advance scientists’ ability to directly image planets and disks around other stars. Coronagraphs work by blocking light from a bright object, like a star, so that the observer can more easily see a faint object, like a planet [next to the bright object].

The Roman Coronagraph is designed to detect planets 100 million times fainter than their stars, or 100 to 1,000 times better than existing space-based coronagraphs.

The Roman Coronagraph will be capable of directly imaging reflected starlight from a planet akin to Jupiter in size, temperature and distance from its parent star.

The Roman telescope and the cosmic dawn

Roman will excel at finding the building blocks of cosmic structures like galaxy clusters that later form. It will quickly identify the densest regions, where more ‘fog’ is being cleared, making Roman a key mission to probe early galaxy evolution and the cosmic dawn.

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Fastest star in the galaxy could unlock black hole secrets

Fastest star in the galaxy could unlock black hole secrets

Speeding through a warped space-time environment

How did the star get so close?

Watch the black hole pull in the fastest star

Fastest star in the galaxy could unlock black hole secrets

Speeding through a warped space-time environment

How did the star get so close?

Watch the black hole pull in the fastest star

The Winter Circle: Catch in the morning before dawn

Winter Circle’s 6 (or 7) bright stars

When to see the Winter Circle

Winter Circle’s 6 (or 7) bright stars

When to see the Winter Circle

Delphinus the Dolphin has a graceful kite shape

How to see Delphinus

The stars of the Dolphin

Deep-sky objects

Delphinus and a neutrino

Delphinus in history and mythology

How to see Delphinus

The stars of the Dolphin

Deep-sky objects

Delphinus and a neutrino

Delphinus in history and mythology

Could there be life in helium atmospheres on exoplanets?

Life in helium atmospheres on exoplanets?

An overlooked possibility

No barriers to life

Helium could help scientists find alien life

Leaking helium reveals atmosphere on rocky exoplanet

Life in helium atmospheres on exoplanets?

An overlooked possibility

No barriers to life

Helium could help scientists find alien life

Leaking helium reveals atmosphere on rocky exoplanet

National parks from space: How many can you name?

How many national parks from space can you name?

Easy: New visitor category

Medium: Backpacker category

Hard: Park ranger category

Answers for the national parks from space quiz

How many national parks from space can you name?

Easy: New visitor category

Medium: Backpacker category

Hard: Park ranger category

Answers for the national parks from space quiz

The return of Sirius in the morning signals seasonal change

Stars and constellations pass behind the sun

The heliacal rising of Sirius

The return of Sirius and the colors of the stars

Stars and constellations pass behind the sun

The heliacal rising of Sirius

The return of Sirius and the colors of the stars

Nancy Grace Roman Space Telescope launches Sunday!

The Nancy Grace Roman Space Telescope launches on Sunday

The Nancy Grace Roman Space Telescope is complete

Meet the Nancy Grace Roman Space Telescope

Interview with Néstor Espinoza

The Roman telescope’s 100,000 new exoplanets

The Roman telescope and the cosmic dawn

The Roman space telescope and dark energy

Who was Nancy Grace Roman?

The Nancy Grace Roman Space Telescope launches on Sunday

The Nancy Grace Roman Space Telescope is complete

Meet the Nancy Grace Roman Space Telescope

Interview with Néstor Espinoza

The Roman telescope’s 100,000 new exoplanets

The Roman telescope and the cosmic dawn

The Roman space telescope and dark energy

Who was Nancy Grace Roman?

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