‘Completely bonkers’ collision of 2 exoplanets observed

Artist’s concept of a collision of 2 exoplanets. Light from the collision in a star system called Gaia20ehk could be seen in the year 2021. Image via Anastasios Tzanidakis/ University of Washington.

• A grad student was looking through old data when he spied something unusual.
• The data revealed the collision of 2 exoplanets, 11,000 light-years away.
• Astronomers hope to detect about 100 similar collisions in the coming decade, using the new Rubin Observatory in Chile. It’s important because this collision might be similar to the one that formed Earth’s moon. And Earth’s moon is key to life.

You deserve a daily dose of good news. For the latest in science and the night sky, subscribe to EarthSky’s free daily newsletter.

Our much-loved EarthSky Community Photos is back, after a bot swarm brought it down a day ago. Please keep sharing your beautiful photos with us.

Collision of 2 exoplanets found in old data

An astronomy grad student at the University of Washington – Anastasios Tzanidakis – was looking through old telescope data when he noticed something odd. It was a seemingly ordinary star, called Gaia20ehk, flickering wildly in brightness. Intrigued, he and his colleagues investigated further. And they determined that the flickering was due to large amounts of hot dust and rocks passing in front of the star. They concluded the flickering of the star must indicate a catastrophic collision between two of its planets, 11,000 light-years away.

Tzanidakis said in a statement:

The star’s light output was nice and flat. But, starting in 2016, it had these three dips in brightness. And then, right around 2021, it went completely bonkers. I can’t emphasize enough that stars like our sun don’t do that. So, when we saw this one, we were like ‘Hello, what’s going on here?’

It’s incredible that various telescopes caught this impact just as the light of the collision reached Earth. There are only a few other planetary collisions of any kind on record, and none that bear so many similarities to the impact that created the Earth and moon.

If we can observe more moments like this elsewhere in the galaxy, it will teach us lots about the formation of our world.

Tzanidakis and his collaborator, James Davenport, published their findings in the peer-reviewed Astrophysical Journal Letters on March 11, 2026.

Chaos in early planetary systems

Stars form from rotating disks of gas and dust. Afterwards, there’s a leftover disk of material called a protoplanetary disk. And at first this disk contains just dust, gas, ice and rocks. But, over millions of years, the materials in the disk coalesce, under gravitational forces. So planets and other small bodies, such as asteroids and comets, form out of the disk.

Conditions with the disk of an early stellar system can be chaotic. Planets can collide and shatter. Or the force of an impact could hurl a planet out of its stellar system. But eventually, over a timescale of 100 million years or so, the new-born solar system settles into a stable state.

Collisions between newly formed extrasolar planets are likely quite common. But catching one in the act is hard. That’s because – in a scenario like the one detected by Anastasios Tzanidakis and colleagues – telescopes can detect the flickering starlight only if the orbiting collision debris is in the line of sight between us and the star.

Star system Gaia20ehk

The star system Gaia20ehk is about 11,000 light-years from Earth. It’s near the direction of the constellation Puppis the Stern. It’s in a stable phase of its evolution, known as the main sequence phase. That means the star is steadily burning hydrogen to helium in its core.

Gaia20ehk is at the center of this image. A small region of the field is shown in the inset box with the star marked by orange crosshairs. It’s about 11,000 light-years from Earth, near the direction of the constellation Pupis the Stern. Image via NASA/NSF NOIRLab/ University of Washington.

Looking in both visible and infrared

For a long time, as viewed through earthly telescopes, Gaia20ehk shone with a steady light. But starting in 2016, Tzanidakis said, there were three dips in its brightness. Then, in 2021, the star’s brightness became erratic.

Davenport suggested they examine this star at infrared wavelengths. And the results were a revelation. Tzanidakis commented:

The infrared light curve was the complete opposite of the visible light. As the visible light began to flicker and dim, the infrared light spiked. Which could mean that the material blocking the star is hot — so hot that it’s glowing in the infrared.

But what caused the dips in light before 2021? Tzanidakis said:

That could be caused by the two planets spiraling closer and closer to each other. At first, they had a series of grazing impacts, which wouldn’t produce a lot of infrared energy. Then, they had their big catastrophic collision, and the infrared really ramped up.

The plot at the top shows Gaia20ehk’s brightness in visible light. There were 3 small dips that were followed, in 2021, by a chaotic variation in brightness. Meanwhile, the bottom plot shows brightness in infrared wavelengths for the same time period. Note that the infrared brightness increased significantly when the visible light brightness was chaotic. Image via Tzanidakis et al./ The Astrophysical Journal Letters/ University of Washington.

Could a similar collision have created our moon?

Some scientists think that a similar collision might have created our moon. They say that about 4.5 billion years ago, an object the size of Mars collided into Earth, ripping out material from our young planet to form the moon.

Gaia20ehk is only slightly more massive than our sun. In addition, the orbiting material causing the star’s fluctuating brightness is about one astronomical unit from the star. So whatever happened in this system to create the debris is located in this star system at about the same distance between our sun and Earth-moon system.

The researchers think the hot debris could, at that distance, eventually cool down enough to create a system similar to our Earth and moon. But they won’t know for sure until the dust literally settles, which could take a few million years.

This is a simulation, from 2022, of how the moon may have formed. A body the size of Mars crashed into Earth, early in its formation, ripping out material that eventually became the moon. Simulation via NASA/ Durham University/ Jacob Kegerreis.

Finding more systems with collisions

In the meantime, the Vera C. Rubin Observatory is making periodic scans of the southern hemisphere sky. If something changes in the sky – a supernova, a new comet, a star changing in brightness – astronomers want to be alerted. They want to study what’s going on in real time.

Davenport thinks that Rubin could find as many as 100 collisions in the coming 10 years. If so, observing these events could help astronomers understand the processes that create Earth–moon-like systems, which in turn could inform the search for habitable exoplanets. Davenport commented:

How rare is the event that created the Earth and moon? That question is fundamental to astrobiology. It seems like the moon is one of the magical ingredients that makes the Earth a good place for life. It can help shield Earth from some asteroids. It produces ocean tides and weather that allow chemistry and biology to mix globally. And it might even play a role in driving tectonic plate activity.

Right now, we don’t know how common these dynamics are. But if we catch more of these collisions, we’ll start to figure it out.

Bottom line: Astronomers found that the erratically flickering light from a stable star was due to debris from the collision of two exoplanets.

Source: Gaia-GIC-1: An Evolving Catastrophic Planetesimal Collision Candidate

Via University of Washington

Rubin Observatory launches real-time alert system

Read more: The tally is in! 6,000 exoplanets now confirmed

The post ‘Completely bonkers’ collision of 2 exoplanets observed first appeared on EarthSky.

from EarthSky https://ift.tt/qlSfCQh

Artist’s concept of a collision of 2 exoplanets. Light from the collision in a star system called Gaia20ehk could be seen in the year 2021. Image via Anastasios Tzanidakis/ University of Washington.

• A grad student was looking through old data when he spied something unusual.
• The data revealed the collision of 2 exoplanets, 11,000 light-years away.
• Astronomers hope to detect about 100 similar collisions in the coming decade, using the new Rubin Observatory in Chile. It’s important because this collision might be similar to the one that formed Earth’s moon. And Earth’s moon is key to life.

You deserve a daily dose of good news. For the latest in science and the night sky, subscribe to EarthSky’s free daily newsletter.

Our much-loved EarthSky Community Photos is back, after a bot swarm brought it down a day ago. Please keep sharing your beautiful photos with us.

Collision of 2 exoplanets found in old data

An astronomy grad student at the University of Washington – Anastasios Tzanidakis – was looking through old telescope data when he noticed something odd. It was a seemingly ordinary star, called Gaia20ehk, flickering wildly in brightness. Intrigued, he and his colleagues investigated further. And they determined that the flickering was due to large amounts of hot dust and rocks passing in front of the star. They concluded the flickering of the star must indicate a catastrophic collision between two of its planets, 11,000 light-years away.

Tzanidakis said in a statement:

The star’s light output was nice and flat. But, starting in 2016, it had these three dips in brightness. And then, right around 2021, it went completely bonkers. I can’t emphasize enough that stars like our sun don’t do that. So, when we saw this one, we were like ‘Hello, what’s going on here?’

It’s incredible that various telescopes caught this impact just as the light of the collision reached Earth. There are only a few other planetary collisions of any kind on record, and none that bear so many similarities to the impact that created the Earth and moon.

If we can observe more moments like this elsewhere in the galaxy, it will teach us lots about the formation of our world.

Tzanidakis and his collaborator, James Davenport, published their findings in the peer-reviewed Astrophysical Journal Letters on March 11, 2026.

Chaos in early planetary systems

Stars form from rotating disks of gas and dust. Afterwards, there’s a leftover disk of material called a protoplanetary disk. And at first this disk contains just dust, gas, ice and rocks. But, over millions of years, the materials in the disk coalesce, under gravitational forces. So planets and other small bodies, such as asteroids and comets, form out of the disk.

Conditions with the disk of an early stellar system can be chaotic. Planets can collide and shatter. Or the force of an impact could hurl a planet out of its stellar system. But eventually, over a timescale of 100 million years or so, the new-born solar system settles into a stable state.

Collisions between newly formed extrasolar planets are likely quite common. But catching one in the act is hard. That’s because – in a scenario like the one detected by Anastasios Tzanidakis and colleagues – telescopes can detect the flickering starlight only if the orbiting collision debris is in the line of sight between us and the star.

Star system Gaia20ehk

The star system Gaia20ehk is about 11,000 light-years from Earth. It’s near the direction of the constellation Puppis the Stern. It’s in a stable phase of its evolution, known as the main sequence phase. That means the star is steadily burning hydrogen to helium in its core.

Gaia20ehk is at the center of this image. A small region of the field is shown in the inset box with the star marked by orange crosshairs. It’s about 11,000 light-years from Earth, near the direction of the constellation Pupis the Stern. Image via NASA/NSF NOIRLab/ University of Washington.

Looking in both visible and infrared

For a long time, as viewed through earthly telescopes, Gaia20ehk shone with a steady light. But starting in 2016, Tzanidakis said, there were three dips in its brightness. Then, in 2021, the star’s brightness became erratic.

Davenport suggested they examine this star at infrared wavelengths. And the results were a revelation. Tzanidakis commented:

The infrared light curve was the complete opposite of the visible light. As the visible light began to flicker and dim, the infrared light spiked. Which could mean that the material blocking the star is hot — so hot that it’s glowing in the infrared.

But what caused the dips in light before 2021? Tzanidakis said:

That could be caused by the two planets spiraling closer and closer to each other. At first, they had a series of grazing impacts, which wouldn’t produce a lot of infrared energy. Then, they had their big catastrophic collision, and the infrared really ramped up.

The plot at the top shows Gaia20ehk’s brightness in visible light. There were 3 small dips that were followed, in 2021, by a chaotic variation in brightness. Meanwhile, the bottom plot shows brightness in infrared wavelengths for the same time period. Note that the infrared brightness increased significantly when the visible light brightness was chaotic. Image via Tzanidakis et al./ The Astrophysical Journal Letters/ University of Washington.

Could a similar collision have created our moon?

Some scientists think that a similar collision might have created our moon. They say that about 4.5 billion years ago, an object the size of Mars collided into Earth, ripping out material from our young planet to form the moon.

Gaia20ehk is only slightly more massive than our sun. In addition, the orbiting material causing the star’s fluctuating brightness is about one astronomical unit from the star. So whatever happened in this system to create the debris is located in this star system at about the same distance between our sun and Earth-moon system.

The researchers think the hot debris could, at that distance, eventually cool down enough to create a system similar to our Earth and moon. But they won’t know for sure until the dust literally settles, which could take a few million years.

This is a simulation, from 2022, of how the moon may have formed. A body the size of Mars crashed into Earth, early in its formation, ripping out material that eventually became the moon. Simulation via NASA/ Durham University/ Jacob Kegerreis.

Finding more systems with collisions

In the meantime, the Vera C. Rubin Observatory is making periodic scans of the southern hemisphere sky. If something changes in the sky – a supernova, a new comet, a star changing in brightness – astronomers want to be alerted. They want to study what’s going on in real time.

Davenport thinks that Rubin could find as many as 100 collisions in the coming 10 years. If so, observing these events could help astronomers understand the processes that create Earth–moon-like systems, which in turn could inform the search for habitable exoplanets. Davenport commented:

How rare is the event that created the Earth and moon? That question is fundamental to astrobiology. It seems like the moon is one of the magical ingredients that makes the Earth a good place for life. It can help shield Earth from some asteroids. It produces ocean tides and weather that allow chemistry and biology to mix globally. And it might even play a role in driving tectonic plate activity.

Right now, we don’t know how common these dynamics are. But if we catch more of these collisions, we’ll start to figure it out.

Bottom line: Astronomers found that the erratically flickering light from a stable star was due to debris from the collision of two exoplanets.

Source: Gaia-GIC-1: An Evolving Catastrophic Planetesimal Collision Candidate

Via University of Washington

Rubin Observatory launches real-time alert system

Read more: The tally is in! 6,000 exoplanets now confirmed

The post ‘Completely bonkers’ collision of 2 exoplanets observed first appeared on EarthSky.

from EarthSky https://ift.tt/qlSfCQh

What makes a halo around the sun or moon?

We tell you all you need to know about halos in our YouTube video here. Don’t forget to subscribe!

What causes halos?

Have you ever looked up and spotted a large ring of light around the sun or moon? Scientists refer to these as 22-degree halos. They got that name because the radius of the circle is always approximately 22 degrees.

There’s an old weather saying: ring around the moon means rain soon. There’s truth to this saying, because high cirrus clouds often come before a storm. Notice in these photos that the sky looks fairly clear. After all, you can see the sun or moon. And yet halos are a sign of high, thin cirrus clouds drifting 20,000 feet (6 km) or more above our heads.

These clouds contain millions of tiny ice crystals. The halos you see are caused by both refraction, or splitting of light, and also by reflection, or glints of light from these ice crystals. The crystals must be oriented and positioned just so with respect to your eye, for the halo to appear.

That’s why, like rainbows, halos around the sun – or moon – are personal. Everyone sees their own unique halo, made by the ice crystals from their point of view. So they are different from the ice crystals making the halo of a person standing next to you.

View at EarthSky Community Photos. | Roberto Ortu captured this moon halo on February 2, 2026, in Italy and wrote: “A moon halo has an apparent radius of 22 degrees and forms around the moon due to refraction by hexagonal-shaped ice crystals that are present in Earth’s atmosphere.” Thank you, Roberto! Notice that – unlike solar halos, which can be colorful – lunar halos are mostly colorless.

A word of caution for photographers

Take care when photographing solar halos. Pointing a camera directly at the unobscured sun can damage it. Never look directly at the sun, even when it is less bright through clouds or fog.

Are halos more common at high latitudes?

We asked Les Cowley of the website Atmospheric Optics if halos around the sun and moon are more frequently seen at high latitudes and less commonly seen closer to the equator. He said:

That’s a good question that is not easy to answer accurately because no halo frequency statistics are collected except in one or two mid-latitude European countries.

We need to distinguish between (a) halos formed by low level diamond dust during very cold weather and (b) halos formed by ice crystals in high cirrus cloud.

Obviously (a) halos only occur in polar regions or countries with very cold winters (Canada for example is not high latitude).

(b) Halos can occur anywhere on the planet during winter or summer. Their frequency depends on the frequency of cirrus coverage and whether it has had a history such that it contains halo forming crystals. The latter is hard to predict. For example, there are major differences in halo frequencies and types of halos across even 200 miles [300 km] in the U.K.

Halos are made by both refraction and reflection ice crystals, such as these, in this photo by Walt Tate. Image via Walt Tate/ Atmospheric Optics. Used with permission.

If you see a halo, notice this!

Because moonlight isn’t very bright, lunar halos are mostly colorless. However, you might notice red on the inside and blue on the outside of the halo. These colors are more noticeable in halos around the sun. If you do see a halo around the moon or sun, notice that the inner edge is sharp, while the outer edge is more diffuse. Also, notice that the sky surrounding the halo is darker than the rest of the sky.

Halo photos from EarthSky’s Community

View at EarthSky Community Photos. | Samit Saha captured this image on January 30, 2026, and wrote: “A bright lunar halo surrounds the moon on a bone-chilling winter night in India. The circular ring formed as moonlight passed through countless hexagonal ice crystals suspended in high, thin cirrostratus clouds, creating the classic 22-degree halo. Snow-covered hills beneath the sky emphasize the clarity and depth of the winter atmosphere. The wide-field view reveals several familiar constellations – Orion, Taurus, Gemini, and the Pleiades – along with the bright planet Jupiter, all sharing the frame with the glowing halo. Such halos often signal approaching weather changes, yet for a brief moment, the sky offered a rare balance of atmospheric optics and celestial geometry, captured in a single exposure.” Thank you, Samit!

View at EarthSky Community Photos. | Bonnie Swan captured this image in Wisconsin on January 21, 2026, and wrote: “While driving east early in the morning, the halo and sun dogs around the rising sun continued to be very bright, when I found a vantage point to get the whole image, I had to pull over to capture it!” Thank you, Bonnie!

View at EarthSky Community Photos. | Dario Giannobile captured this in Manhattan on December 12, 2025, and wrote: “In a handheld shot of the Statue of Liberty taken from the ferry connecting Ellis Island to Manhattan, with seagulls crossing the sky, a series of rare optical phenomena framed the Statue’s crown. These are complex interactions of light with small ice crystals suspended in the air. This rare atmospheric condition created an extraordinary scene: a perfect solar halo, accompanied by parhelia (so-called “false suns”), a parhelic arc and a superior tangent arc.” Thank you, Dario!

More halo photos from our friends

Everyone sees his or her own halo. That’s because – for every individual – a solar or lunar halo is made of light reflecting and refracting from different ice crystals in high, thin cirrus clouds. Image via Vincenzo Mirabella/ NASA. Used with permission.

View at EarthSky Community Photos. | Amrinderjit Singh captured this photo from India on December 12, 2025, and wrote: “At 2200 meters high in the mountains, the sky offered its beauty by displaying a halo around the sun and I was right there to capture this beautiful landscape.” Thank you, Amrinderjit!

View at EarthSky Community Photos. | Teresa Raines captured this image from Arizona on January 4, 2026, and wrote: “Lunar halo, with Orion in the bottom right corner, Jupiter next to moon peeking through top palm tree frond.” Thank you, Teresa!

Eliot Herman wrote on May 5, 2018: “This shows the change that occurred over 7 minutes as a lunar halo emerged. It then persisted for about 40 minutes and disappeared with increasing clouds. Although it appears the halo is forming from an odd shape, what is actually illuminated is the edge of the clouds just before the halo formed as the clouds drifted in front of the moon. But it does have a nice illusion of an odd-shaped halo then becoming round.” Used with permission.

Thank you to all who submit images to EarthSky Community Photos! View community photos here. We love you all. Submit your photos here.

Bottom line: High, thin cirrus clouds drifting high above your head create the halos you see around the sun or moon. The halos are from tiny ice crystals in Earth’s atmosphere. They do it by refracting and reflecting the light. Lunar halos are signs that storms are nearby.

The post What makes a halo around the sun or moon? first appeared on EarthSky.

from EarthSky https://ift.tt/yYs1t5D

We tell you all you need to know about halos in our YouTube video here. Don’t forget to subscribe!

What causes halos?

Have you ever looked up and spotted a large ring of light around the sun or moon? Scientists refer to these as 22-degree halos. They got that name because the radius of the circle is always approximately 22 degrees.

There’s an old weather saying: ring around the moon means rain soon. There’s truth to this saying, because high cirrus clouds often come before a storm. Notice in these photos that the sky looks fairly clear. After all, you can see the sun or moon. And yet halos are a sign of high, thin cirrus clouds drifting 20,000 feet (6 km) or more above our heads.

These clouds contain millions of tiny ice crystals. The halos you see are caused by both refraction, or splitting of light, and also by reflection, or glints of light from these ice crystals. The crystals must be oriented and positioned just so with respect to your eye, for the halo to appear.

That’s why, like rainbows, halos around the sun – or moon – are personal. Everyone sees their own unique halo, made by the ice crystals from their point of view. So they are different from the ice crystals making the halo of a person standing next to you.

View at EarthSky Community Photos. | Roberto Ortu captured this moon halo on February 2, 2026, in Italy and wrote: “A moon halo has an apparent radius of 22 degrees and forms around the moon due to refraction by hexagonal-shaped ice crystals that are present in Earth’s atmosphere.” Thank you, Roberto! Notice that – unlike solar halos, which can be colorful – lunar halos are mostly colorless.

A word of caution for photographers

Take care when photographing solar halos. Pointing a camera directly at the unobscured sun can damage it. Never look directly at the sun, even when it is less bright through clouds or fog.

Are halos more common at high latitudes?

We asked Les Cowley of the website Atmospheric Optics if halos around the sun and moon are more frequently seen at high latitudes and less commonly seen closer to the equator. He said:

That’s a good question that is not easy to answer accurately because no halo frequency statistics are collected except in one or two mid-latitude European countries.

We need to distinguish between (a) halos formed by low level diamond dust during very cold weather and (b) halos formed by ice crystals in high cirrus cloud.

Obviously (a) halos only occur in polar regions or countries with very cold winters (Canada for example is not high latitude).

(b) Halos can occur anywhere on the planet during winter or summer. Their frequency depends on the frequency of cirrus coverage and whether it has had a history such that it contains halo forming crystals. The latter is hard to predict. For example, there are major differences in halo frequencies and types of halos across even 200 miles [300 km] in the U.K.

Halos are made by both refraction and reflection ice crystals, such as these, in this photo by Walt Tate. Image via Walt Tate/ Atmospheric Optics. Used with permission.

If you see a halo, notice this!

Because moonlight isn’t very bright, lunar halos are mostly colorless. However, you might notice red on the inside and blue on the outside of the halo. These colors are more noticeable in halos around the sun. If you do see a halo around the moon or sun, notice that the inner edge is sharp, while the outer edge is more diffuse. Also, notice that the sky surrounding the halo is darker than the rest of the sky.

Halo photos from EarthSky’s Community

View at EarthSky Community Photos. | Samit Saha captured this image on January 30, 2026, and wrote: “A bright lunar halo surrounds the moon on a bone-chilling winter night in India. The circular ring formed as moonlight passed through countless hexagonal ice crystals suspended in high, thin cirrostratus clouds, creating the classic 22-degree halo. Snow-covered hills beneath the sky emphasize the clarity and depth of the winter atmosphere. The wide-field view reveals several familiar constellations – Orion, Taurus, Gemini, and the Pleiades – along with the bright planet Jupiter, all sharing the frame with the glowing halo. Such halos often signal approaching weather changes, yet for a brief moment, the sky offered a rare balance of atmospheric optics and celestial geometry, captured in a single exposure.” Thank you, Samit!

View at EarthSky Community Photos. | Bonnie Swan captured this image in Wisconsin on January 21, 2026, and wrote: “While driving east early in the morning, the halo and sun dogs around the rising sun continued to be very bright, when I found a vantage point to get the whole image, I had to pull over to capture it!” Thank you, Bonnie!

View at EarthSky Community Photos. | Dario Giannobile captured this in Manhattan on December 12, 2025, and wrote: “In a handheld shot of the Statue of Liberty taken from the ferry connecting Ellis Island to Manhattan, with seagulls crossing the sky, a series of rare optical phenomena framed the Statue’s crown. These are complex interactions of light with small ice crystals suspended in the air. This rare atmospheric condition created an extraordinary scene: a perfect solar halo, accompanied by parhelia (so-called “false suns”), a parhelic arc and a superior tangent arc.” Thank you, Dario!

More halo photos from our friends

Everyone sees his or her own halo. That’s because – for every individual – a solar or lunar halo is made of light reflecting and refracting from different ice crystals in high, thin cirrus clouds. Image via Vincenzo Mirabella/ NASA. Used with permission.

View at EarthSky Community Photos. | Amrinderjit Singh captured this photo from India on December 12, 2025, and wrote: “At 2200 meters high in the mountains, the sky offered its beauty by displaying a halo around the sun and I was right there to capture this beautiful landscape.” Thank you, Amrinderjit!

View at EarthSky Community Photos. | Teresa Raines captured this image from Arizona on January 4, 2026, and wrote: “Lunar halo, with Orion in the bottom right corner, Jupiter next to moon peeking through top palm tree frond.” Thank you, Teresa!

Eliot Herman wrote on May 5, 2018: “This shows the change that occurred over 7 minutes as a lunar halo emerged. It then persisted for about 40 minutes and disappeared with increasing clouds. Although it appears the halo is forming from an odd shape, what is actually illuminated is the edge of the clouds just before the halo formed as the clouds drifted in front of the moon. But it does have a nice illusion of an odd-shaped halo then becoming round.” Used with permission.

Thank you to all who submit images to EarthSky Community Photos! View community photos here. We love you all. Submit your photos here.

Bottom line: High, thin cirrus clouds drifting high above your head create the halos you see around the sun or moon. The halos are from tiny ice crystals in Earth’s atmosphere. They do it by refracting and reflecting the light. Lunar halos are signs that storms are nearby.

The post What makes a halo around the sun or moon? first appeared on EarthSky.

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See the year’s fastest sunsets and sunrises around equinoxes

View at EarthSky Community Photos. | Hamza Khan in Pakistan captured the sun’s position at sunset on 2 equinoxes and 2 solstices in this composite photo. Thank you, Hamza!

Year’s fastest sunsets and sunrises

The March equinox is coming up fast. It’ll come at 14:46 UTC (9:46 a.m. CDT) on March 20, 2026. And here’s a little-known equinox phenomenon: the sun sets faster around the time of an equinox. The fastest sunrises happen at or near the equinoxes, too. On the other hand, the slowest sunsets (and sunrises) happen around the solstices. It’s true whether you live in Earth’s Northern or Southern Hemisphere.

By the way, when we say sunset here, we’re talking about the actual number of minutes it takes for the body of the sun to sink below the western horizon.

So why does it happen? Why does the body of the sun fall below the horizon so quickly at equinox-time? It’s because, at every equinox, the sun rises due east and sets due west. That means – on the day of an equinox – the setting sun hits the horizon at its steepest possible angle.

The equinox is an event that takes place in Earth’s orbit around the sun. Image via National Weather Service/ weather.gov.

Year’s slowest sunsets and sunrises

Meanwhile, at a solstice, the sun is setting farthest north or farthest south of due west. And, the farther the sun sets from due west along the horizon, the shallower the angle of the setting sun. So that means a longer duration for sunset at the solstices.

Also, the sunset duration varies by latitude. Farther north or south on the Earth’s globe, the duration of sunset lasts longer. So, closer to the equator, the duration is shorter. But let’s just consider one latitude, 40 degrees north, the latitude of Denver or Philadelphia in the United States; parts of Spain; and Beijing, China.

At that latitude, on the day of equinox, the sun sets in about 2 3/4 minutes.

On the other hand, the solstice sun sets in roughly 3 1/4 minutes at 40 degrees latitude.

Sunset images from the EarthSky community

View at EarthSky Community Photos. | Teresa Molinaro captured this image on August 28, 2024, in Italy. Teresa wrote: “A very intense dawn occurred on the morning of late September; and in the seaside village everything was silent.” Thank you, Teresa!

View at EarthSky Community Photos. | Peter Lowenstein captured these images and wrote: “Equinox sunsets before and after equinox sunrise on 23 September. The instant of the Southern Hemisphere spring equinox in 2023 was at 6.50 UTC on 23 September. This means it was possible to record two equinox sunsets one on the 22nd a few hours before and another a few hours after the equinox sunrise on the 23rd. These are shown in the accompanying composite of three 9 video frame montages.” Thank you, Peter!

Bottom line: The fastest sunsets and sunrises of the year are happening now, around the time of the September equinox.

2025 September equinox: All you need to know

Are day and night equal on the equinox?

Help support EarthSky! Visit the EarthSky store for to see the great selection of educational tools and team gear we have to offer.

The post See the year’s fastest sunsets and sunrises around equinoxes first appeared on EarthSky.

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View at EarthSky Community Photos. | Hamza Khan in Pakistan captured the sun’s position at sunset on 2 equinoxes and 2 solstices in this composite photo. Thank you, Hamza!

Year’s fastest sunsets and sunrises

The March equinox is coming up fast. It’ll come at 14:46 UTC (9:46 a.m. CDT) on March 20, 2026. And here’s a little-known equinox phenomenon: the sun sets faster around the time of an equinox. The fastest sunrises happen at or near the equinoxes, too. On the other hand, the slowest sunsets (and sunrises) happen around the solstices. It’s true whether you live in Earth’s Northern or Southern Hemisphere.

By the way, when we say sunset here, we’re talking about the actual number of minutes it takes for the body of the sun to sink below the western horizon.

So why does it happen? Why does the body of the sun fall below the horizon so quickly at equinox-time? It’s because, at every equinox, the sun rises due east and sets due west. That means – on the day of an equinox – the setting sun hits the horizon at its steepest possible angle.

The equinox is an event that takes place in Earth’s orbit around the sun. Image via National Weather Service/ weather.gov.

Year’s slowest sunsets and sunrises

Meanwhile, at a solstice, the sun is setting farthest north or farthest south of due west. And, the farther the sun sets from due west along the horizon, the shallower the angle of the setting sun. So that means a longer duration for sunset at the solstices.

Also, the sunset duration varies by latitude. Farther north or south on the Earth’s globe, the duration of sunset lasts longer. So, closer to the equator, the duration is shorter. But let’s just consider one latitude, 40 degrees north, the latitude of Denver or Philadelphia in the United States; parts of Spain; and Beijing, China.

At that latitude, on the day of equinox, the sun sets in about 2 3/4 minutes.

On the other hand, the solstice sun sets in roughly 3 1/4 minutes at 40 degrees latitude.

Sunset images from the EarthSky community

View at EarthSky Community Photos. | Teresa Molinaro captured this image on August 28, 2024, in Italy. Teresa wrote: “A very intense dawn occurred on the morning of late September; and in the seaside village everything was silent.” Thank you, Teresa!

View at EarthSky Community Photos. | Peter Lowenstein captured these images and wrote: “Equinox sunsets before and after equinox sunrise on 23 September. The instant of the Southern Hemisphere spring equinox in 2023 was at 6.50 UTC on 23 September. This means it was possible to record two equinox sunsets one on the 22nd a few hours before and another a few hours after the equinox sunrise on the 23rd. These are shown in the accompanying composite of three 9 video frame montages.” Thank you, Peter!

Bottom line: The fastest sunsets and sunrises of the year are happening now, around the time of the September equinox.

2025 September equinox: All you need to know

Are day and night equal on the equinox?

Help support EarthSky! Visit the EarthSky store for to see the great selection of educational tools and team gear we have to offer.

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March equinox 2026: Here’s all you need to know

Satellite views of Earth on the solstices and equinoxes. We are at the March equinox now. Read more about this image. Images via NASA Earth Observatory.

The March equinox has arrived! Here’s all you need to know about it.

What is it? The March equinox – aka the vernal equinox – marks the sun’s crossing above Earth’s equator, moving from south to north. Earth’s tilt on its axis is what causes this northward shift of the sun’s path across our sky at this time of year. Earth’s tilt is now bringing spring and summer to the Northern Hemisphere. At the same time, the March equinox marks the beginning of autumn – and a shift toward winter – in the Southern Hemisphere.
When is it? The sun crosses the celestial equator – a line directly above Earth’s equator – at 14:46 UTC on March 20, 2026 (9:46 a.m. CDT).

No matter where you are on Earth, the equinox brings us a number of seasonal effects, noticeable to nature lovers around the globe.

Equal day and night on the equinox?

At the equinox, Earth’s two hemispheres are receiving the sun’s rays equally. Night and day are often said to be equal in length. In fact, the word equinox comes from the Latin aequus (equal) and nox (night). For our ancestors, whose timekeeping was less precise than ours, day and night likely did seem equal. But today we know it’s not exactly so.

Read more: Are day and night equal at the equinox?

Fastest sunsets at the equinoxes

The fastest sunsets and sunrises of the year happen at the equinoxes. We’re talking here about the length of time it takes for the whole sun to sink below the horizon.

Read more: Fastest sunsets happen near equinoxes

View at EarthSky Community Photos. | Iaroslav Kourzenkov of Halifax, Nova Scotia, Canada, captured this image of the sunset on the equinox on March 20, 2023. Thank you, Iaroslav!

Sun rises due east and sets due west?

Here’s another equinox phenomenon. You might hear that the sun rises due east and sets due west at the equinox. Is that true? Yes it is. In fact, it’s the case no matter where you live on Earth, with the exception of the North and South Poles. At the equinoxes, the sun appears overhead at noon as seen from Earth’s equator, as the illustration below shows. This illustration shows the sun’s location on the celestial equator, every hour, on the day of the equinox.

No matter where you are on Earth – except at the Earth’s North and South Poles – you have a due east and due west point on your horizon. That point marks the intersection of your horizon with the celestial equator: the imaginary line above the true equator of the Earth.

The sun is on the celestial equator, and the celestial equator intersects all of our horizons at points due east and due west. Voila! The sun rises due east and sets due west.

Read more: Sun rises due east and sets due west

The day arc of the sun, every hour, at the equinox, as seen on the (imaginary) celestial sphere surrounding Earth. At the equinox, the sun is directly above Earth’s equator. Image via Tau’olunga/ Wikimedia Commons (CC BY-SA 2.5).

More March equinox effects

And there are also plenty more effects in play around the time of the March equinox that all of us can notice. In the Northern Hemisphere, the March equinox brings earlier sunrises, later sunsets and sprouting plants.

Meanwhile, you’ll find the opposite season – later sunrises, earlier sunsets, chillier winds, dry and falling leaves – south of the equator.

The equinoxes and solstices are caused by Earth’s tilt on its axis and ceaseless motion in orbit. You can think of an equinox as happening on the imaginary dome of our sky, or as an event that happens in Earth’s orbit around the sun.

The Earth-centered view

If you think of it from an Earth-centered perspective, you can think of the celestial equator as a great circle dividing Earth’s sky into its Northern and Southern Hemispheres. The celestial equator is an imaginary line wrapping the sky directly above Earth’s equator. At the equinox, the sun crosses the celestial equator to enter the sky’s Northern Hemisphere.

The day arc of the equinox sun as seen from Earth’s equator. Also showing are twilight suns (in red) down to -18 degrees altitude. Note that the sun is at its highest point at noon. And see that the tree’s shadow at noon is cast straight down. That is – as seen from the equator on the day of an equinox – a tree stands in the center of its own shadow. Image via Tau’olunga/ Wikimedia Commons (CC BY-SA 2.5).

The Earth-in-space view

If you think of it from an Earth-in-space perspective, you have to think of Earth in orbit around the sun. And we all know Earth doesn’t orbit upright but is instead tilted on its axis by 23 1/2 degrees. So Earth’s Northern and Southern Hemispheres trade places in receiving the sun’s light and warmth most directly. We have an equinox twice a year – spring and fall – when the tilt of the Earth’s axis and Earth’s orbit around the sun combine in such a way that the axis is inclined neither away from nor toward the sun.

Here are satellite views of Earth on the solstices and equinoxes, via NASA Earth Observatory.

Things change fast around the equinoxes

Since Earth never stops moving around the sun, the position of the sunrise and sunset – and the days of approximately equal sunlight and night – will change quickly.

The video below was the Astronomy Picture of the Day for March 19, 2014. APOD explained:

At an equinox, the Earth’s terminator – the dividing line between day and night – becomes vertical and connects the North and South Poles. The time-lapse video [above] demonstrates this by displaying an entire year on planet Earth in 12 seconds. From geosynchronous orbit, the Meteosat satellite recorded these infrared images of the Earth every day at the same local time. The video started at the September 2010 equinox with the terminator line being vertical.

As the Earth revolved around the sun, the terminator was seen to tilt in a way that provides less daily sunlight to the Northern Hemisphere, causing winter in the north. As the year progressed, the March 2011 equinox arrived halfway through the video, followed by the terminator tilting the other way, causing winter in the Southern Hemisphere and summer in the north. The captured year ends again with the September equinox, concluding another of billions of trips the Earth has taken – and will take – around the sun.

The equinox is an event that takes place in Earth’s orbit around the sun. Image via National Weather Service/ weather.gov.

Where are signs of the March equinox in nature?

Everywhere! Forget about the weather for a moment, and think only about daylight. In terms of daylight, the knowledge that spring is here – and summer is coming – permeates all of nature on the northern half of Earth’s globe.

Notice the arc of the sun across the sky each day. You’ll find that it’s shifting toward the north. Responding to the change in daylight, birds and butterflies are migrating back northward, too, along with the path of the sun.

The longer days do bring with them warmer weather. People are leaving their winter coats at home. Trees are budding, and plants are beginning a new cycle of growth. In many places, spring flowers are beginning to bloom.

Meanwhile, in the Southern Hemisphere, the days are getting shorter and nights longer. A chill is in the air. Fall is here, and winter is coming!

Bottom line: Happy equinox! The 2026 March equinox falls March 20 at 14:46 UTC. All you need to know about the March equinox here.

The post March equinox 2026: Here’s all you need to know first appeared on EarthSky.

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Satellite views of Earth on the solstices and equinoxes. We are at the March equinox now. Read more about this image. Images via NASA Earth Observatory.

The March equinox has arrived! Here’s all you need to know about it.

What is it? The March equinox – aka the vernal equinox – marks the sun’s crossing above Earth’s equator, moving from south to north. Earth’s tilt on its axis is what causes this northward shift of the sun’s path across our sky at this time of year. Earth’s tilt is now bringing spring and summer to the Northern Hemisphere. At the same time, the March equinox marks the beginning of autumn – and a shift toward winter – in the Southern Hemisphere.
When is it? The sun crosses the celestial equator – a line directly above Earth’s equator – at 14:46 UTC on March 20, 2026 (9:46 a.m. CDT).

No matter where you are on Earth, the equinox brings us a number of seasonal effects, noticeable to nature lovers around the globe.

Equal day and night on the equinox?

At the equinox, Earth’s two hemispheres are receiving the sun’s rays equally. Night and day are often said to be equal in length. In fact, the word equinox comes from the Latin aequus (equal) and nox (night). For our ancestors, whose timekeeping was less precise than ours, day and night likely did seem equal. But today we know it’s not exactly so.

Read more: Are day and night equal at the equinox?

Fastest sunsets at the equinoxes

The fastest sunsets and sunrises of the year happen at the equinoxes. We’re talking here about the length of time it takes for the whole sun to sink below the horizon.

Read more: Fastest sunsets happen near equinoxes

View at EarthSky Community Photos. | Iaroslav Kourzenkov of Halifax, Nova Scotia, Canada, captured this image of the sunset on the equinox on March 20, 2023. Thank you, Iaroslav!

Sun rises due east and sets due west?

Here’s another equinox phenomenon. You might hear that the sun rises due east and sets due west at the equinox. Is that true? Yes it is. In fact, it’s the case no matter where you live on Earth, with the exception of the North and South Poles. At the equinoxes, the sun appears overhead at noon as seen from Earth’s equator, as the illustration below shows. This illustration shows the sun’s location on the celestial equator, every hour, on the day of the equinox.

No matter where you are on Earth – except at the Earth’s North and South Poles – you have a due east and due west point on your horizon. That point marks the intersection of your horizon with the celestial equator: the imaginary line above the true equator of the Earth.

The sun is on the celestial equator, and the celestial equator intersects all of our horizons at points due east and due west. Voila! The sun rises due east and sets due west.

Read more: Sun rises due east and sets due west

The day arc of the sun, every hour, at the equinox, as seen on the (imaginary) celestial sphere surrounding Earth. At the equinox, the sun is directly above Earth’s equator. Image via Tau’olunga/ Wikimedia Commons (CC BY-SA 2.5).

More March equinox effects

And there are also plenty more effects in play around the time of the March equinox that all of us can notice. In the Northern Hemisphere, the March equinox brings earlier sunrises, later sunsets and sprouting plants.

Meanwhile, you’ll find the opposite season – later sunrises, earlier sunsets, chillier winds, dry and falling leaves – south of the equator.

The equinoxes and solstices are caused by Earth’s tilt on its axis and ceaseless motion in orbit. You can think of an equinox as happening on the imaginary dome of our sky, or as an event that happens in Earth’s orbit around the sun.

The Earth-centered view

If you think of it from an Earth-centered perspective, you can think of the celestial equator as a great circle dividing Earth’s sky into its Northern and Southern Hemispheres. The celestial equator is an imaginary line wrapping the sky directly above Earth’s equator. At the equinox, the sun crosses the celestial equator to enter the sky’s Northern Hemisphere.

The day arc of the equinox sun as seen from Earth’s equator. Also showing are twilight suns (in red) down to -18 degrees altitude. Note that the sun is at its highest point at noon. And see that the tree’s shadow at noon is cast straight down. That is – as seen from the equator on the day of an equinox – a tree stands in the center of its own shadow. Image via Tau’olunga/ Wikimedia Commons (CC BY-SA 2.5).

The Earth-in-space view

If you think of it from an Earth-in-space perspective, you have to think of Earth in orbit around the sun. And we all know Earth doesn’t orbit upright but is instead tilted on its axis by 23 1/2 degrees. So Earth’s Northern and Southern Hemispheres trade places in receiving the sun’s light and warmth most directly. We have an equinox twice a year – spring and fall – when the tilt of the Earth’s axis and Earth’s orbit around the sun combine in such a way that the axis is inclined neither away from nor toward the sun.

Here are satellite views of Earth on the solstices and equinoxes, via NASA Earth Observatory.

Things change fast around the equinoxes

Since Earth never stops moving around the sun, the position of the sunrise and sunset – and the days of approximately equal sunlight and night – will change quickly.

The video below was the Astronomy Picture of the Day for March 19, 2014. APOD explained:

At an equinox, the Earth’s terminator – the dividing line between day and night – becomes vertical and connects the North and South Poles. The time-lapse video [above] demonstrates this by displaying an entire year on planet Earth in 12 seconds. From geosynchronous orbit, the Meteosat satellite recorded these infrared images of the Earth every day at the same local time. The video started at the September 2010 equinox with the terminator line being vertical.

As the Earth revolved around the sun, the terminator was seen to tilt in a way that provides less daily sunlight to the Northern Hemisphere, causing winter in the north. As the year progressed, the March 2011 equinox arrived halfway through the video, followed by the terminator tilting the other way, causing winter in the Southern Hemisphere and summer in the north. The captured year ends again with the September equinox, concluding another of billions of trips the Earth has taken – and will take – around the sun.

The equinox is an event that takes place in Earth’s orbit around the sun. Image via National Weather Service/ weather.gov.

Where are signs of the March equinox in nature?

Everywhere! Forget about the weather for a moment, and think only about daylight. In terms of daylight, the knowledge that spring is here – and summer is coming – permeates all of nature on the northern half of Earth’s globe.

Notice the arc of the sun across the sky each day. You’ll find that it’s shifting toward the north. Responding to the change in daylight, birds and butterflies are migrating back northward, too, along with the path of the sun.

The longer days do bring with them warmer weather. People are leaving their winter coats at home. Trees are budding, and plants are beginning a new cycle of growth. In many places, spring flowers are beginning to bloom.

Meanwhile, in the Southern Hemisphere, the days are getting shorter and nights longer. A chill is in the air. Fall is here, and winter is coming!

Bottom line: Happy equinox! The 2026 March equinox falls March 20 at 14:46 UTC. All you need to know about the March equinox here.

The post March equinox 2026: Here’s all you need to know first appeared on EarthSky.

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Happy Pi Day! Ways to celebrate here

We know what pie is, but what is pi? It’s the number that results from dividing the circumference of any circle by its diameter. Although pi is an infinite number, it’s usually rounded off to 3.14. Hence, Pi Day on March 14! Image via Delft University of Technology/ Wikimedia Commons.

Have you heard of Pi Day? It happens every year on March 14. The numbers 3-1-4 are the first three digits of the famous mathematical constant pi, which, in case you’re wondering, is the ratio of the circumference of a circle to its diameter.

No matter how large or small the circle, that ratio always works out to 3.14. That’s the magic of mathematics.

Plus, pi is a never-ending number. You often see it written as 3.14, but in fact it’s approximately equal to 3.14159 … and so on, into infinity. That sense of infinity is in part what makes pi – and Pi Day – so much fun.

So here’s a quick guide to Pi Day, which is celebrated by science aficionados all over the world. It is a unique combination of fun and education, and anyone can participate.

What is pi? It’s the number that results from dividing the circumference of any circle by its diameter. Although pi is an infinite number, it’s usually rounded off to 3.14. Hence, Pi Day on March 14! Image via NASA/ JPL-Caltech.

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.

5 facts about pi

People compete in memorizing it. Rajveer Meena has the record for memorizing the most decimal places of pi at 70,000.

It’s used as stress tests for computers. Computing pi is a kind of “digital cardiogram” for computers.

A Givenchy men’s cologne is named pi. So you can smell like pi, too, if you are the intellectual and visionary kind.

Pi by other names. Pi is also known as Archimedes’ constant or Ludolph’s number.

Heroes sometimes use pi. For example, Spock foils an evil computer in Wolf in the Fold (the 14th episode of the second season of the American sci-fi TV series “Star Trek”), by preoccupying it forever by having it calculate pi’s value.

By happy coincidence, March 14 is also Albert Einstein’s birthday!

Here are a couple of other online sources to help you celebrate Pi Day:

Join the Exploratorium’s annual celebration.

Check out this Pi Day overview.

Or enjoy some trivia via National Today.

Happy Pi Day! Pi is a mathematical constant. It equals 3.14159 … and so on, into infinity. So for short, we refer to pi as 3.14. Image via NASA/ JPL-Caltech.

History of Pi Day

Physicist Larry Shaw founded Pi Day in 1988, as part of his great work at the ground-breaking science museum Exploratorium in San Francisco. During the first festivities, both staff and the public marched around one of the circular spaces in the museum while eating fruit pies.

In the United States, the U.S. House of Representatives officially recognized Pi Day as an annual event – National Pi Day – on March 12, 2009.

Today, many people and institutions celebrate, including students, teachers, parents, museums, science centers and planetariums.

Physicist Larry Shaw founded Pi Day in 1988 at the famous Exploratorium science museum in San Francisco. Image via Ronhip/ Wikimedia Commons (CC BY-SA 3.0).

Celebrate Pi Day with NASA

At the NASA site you can find many resources, including a Pi Day Challenge, along with lessons and downloads. The challenge allows the public to solve some of the same problems NASA scientists and engineers do using pi.

Take part in the NASA Pi Day Challenge and find a list of handy resources below. Image via NASA/ JPL.

More NASA resources

Here are more resources and ways you can celebrate, including:

18 Ways NASA Uses Pi

How Many Decimals of Pi Do We Really Need?

Pi in the Sky Lessons

Infographic: Planet Pi

In addition, you can also download mobile and web backgrounds on The NASA Pi Day Challenge page.

A ‘pi planet’

By the way, did you know that there’s even a pi planet? It is an exoplanet known as K2-315b, whose orbital period matches the value of pi. That is, this planet orbits its star every 3.14 Earth days.

It is, in fact, almost the same size as Earth, with a radius 95% that of our own planet. That’s also about the same size as Venus, and like our nearby sister world, it’s a blisteringly hot place, with temperatures up to 350 degrees Fahrenheit (177 degrees C). It orbits a red dwarf (or M-type dwarf) star that’s cooler than our sun and only about 1/5 as large, called EPIC 249631677, which is 186 light-years from Earth.

There is even a “pi planet.” This is an artist’s concept of K2-315b, which has an orbital period of 3.14 Earth days, the same value as pi. Image via NASA Ames/ JPL-Caltech/ T. Pyle/ Christine Daniloff/ MIT (CC BY-NC-ND 4.0).

Bottom line: March 14 is Pi Day, an annual mathematical event for science lovers. Here’s how to celebrate and take part in the NASA Pi Day Challenge!

Via NASA

Via piday.org

The post Happy Pi Day! Ways to celebrate here first appeared on EarthSky.

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We know what pie is, but what is pi? It’s the number that results from dividing the circumference of any circle by its diameter. Although pi is an infinite number, it’s usually rounded off to 3.14. Hence, Pi Day on March 14! Image via Delft University of Technology/ Wikimedia Commons.

Have you heard of Pi Day? It happens every year on March 14. The numbers 3-1-4 are the first three digits of the famous mathematical constant pi, which, in case you’re wondering, is the ratio of the circumference of a circle to its diameter.

No matter how large or small the circle, that ratio always works out to 3.14. That’s the magic of mathematics.

Plus, pi is a never-ending number. You often see it written as 3.14, but in fact it’s approximately equal to 3.14159 … and so on, into infinity. That sense of infinity is in part what makes pi – and Pi Day – so much fun.

So here’s a quick guide to Pi Day, which is celebrated by science aficionados all over the world. It is a unique combination of fun and education, and anyone can participate.

What is pi? It’s the number that results from dividing the circumference of any circle by its diameter. Although pi is an infinite number, it’s usually rounded off to 3.14. Hence, Pi Day on March 14! Image via NASA/ JPL-Caltech.

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.

5 facts about pi

People compete in memorizing it. Rajveer Meena has the record for memorizing the most decimal places of pi at 70,000.

It’s used as stress tests for computers. Computing pi is a kind of “digital cardiogram” for computers.

A Givenchy men’s cologne is named pi. So you can smell like pi, too, if you are the intellectual and visionary kind.

Pi by other names. Pi is also known as Archimedes’ constant or Ludolph’s number.

Heroes sometimes use pi. For example, Spock foils an evil computer in Wolf in the Fold (the 14th episode of the second season of the American sci-fi TV series “Star Trek”), by preoccupying it forever by having it calculate pi’s value.

By happy coincidence, March 14 is also Albert Einstein’s birthday!

Here are a couple of other online sources to help you celebrate Pi Day:

Join the Exploratorium’s annual celebration.

Check out this Pi Day overview.

Or enjoy some trivia via National Today.

Happy Pi Day! Pi is a mathematical constant. It equals 3.14159 … and so on, into infinity. So for short, we refer to pi as 3.14. Image via NASA/ JPL-Caltech.

History of Pi Day

Physicist Larry Shaw founded Pi Day in 1988, as part of his great work at the ground-breaking science museum Exploratorium in San Francisco. During the first festivities, both staff and the public marched around one of the circular spaces in the museum while eating fruit pies.

In the United States, the U.S. House of Representatives officially recognized Pi Day as an annual event – National Pi Day – on March 12, 2009.

Today, many people and institutions celebrate, including students, teachers, parents, museums, science centers and planetariums.

Physicist Larry Shaw founded Pi Day in 1988 at the famous Exploratorium science museum in San Francisco. Image via Ronhip/ Wikimedia Commons (CC BY-SA 3.0).

Celebrate Pi Day with NASA

At the NASA site you can find many resources, including a Pi Day Challenge, along with lessons and downloads. The challenge allows the public to solve some of the same problems NASA scientists and engineers do using pi.

Take part in the NASA Pi Day Challenge and find a list of handy resources below. Image via NASA/ JPL.

More NASA resources

Here are more resources and ways you can celebrate, including:

18 Ways NASA Uses Pi

How Many Decimals of Pi Do We Really Need?

Pi in the Sky Lessons

Infographic: Planet Pi

In addition, you can also download mobile and web backgrounds on The NASA Pi Day Challenge page.

A ‘pi planet’

By the way, did you know that there’s even a pi planet? It is an exoplanet known as K2-315b, whose orbital period matches the value of pi. That is, this planet orbits its star every 3.14 Earth days.

It is, in fact, almost the same size as Earth, with a radius 95% that of our own planet. That’s also about the same size as Venus, and like our nearby sister world, it’s a blisteringly hot place, with temperatures up to 350 degrees Fahrenheit (177 degrees C). It orbits a red dwarf (or M-type dwarf) star that’s cooler than our sun and only about 1/5 as large, called EPIC 249631677, which is 186 light-years from Earth.

There is even a “pi planet.” This is an artist’s concept of K2-315b, which has an orbital period of 3.14 Earth days, the same value as pi. Image via NASA Ames/ JPL-Caltech/ T. Pyle/ Christine Daniloff/ MIT (CC BY-NC-ND 4.0).

Bottom line: March 14 is Pi Day, an annual mathematical event for science lovers. Here’s how to celebrate and take part in the NASA Pi Day Challenge!

Via NASA

Via piday.org

The post Happy Pi Day! Ways to celebrate here first appeared on EarthSky.

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Our sun might be a migrant from the inner Milky Way

A new study suggests our sun might be a migrant from a more central region of our home galaxy, the Milky Way. It suggests our sun joined a migration of other stars, which moved outward from the inner part of the galaxy some 4 to 6 billion years ago. Image via NAOJ/ EurekaAlert.

• Astronomers suggest the sun might have migrated from near the central bar-shaped nucleus of our Milky Way galaxy.
• Scientists studied 6,594 solar “twin” stars, using Gaia data. Many share the sun’s age (about 4–6 billion years) and appear to have migrated outward from the galaxy’s inner regions together.
• The sun eventually took up residence in a quieter part of the galaxy, where planets (and life) could develop with fewer threats.

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

Our sun might be a migrant

Astronomers have long thought our sun was born closer to the center of our Milky Way galaxy than it is today.

The stumbling block to that idea has been the Milky Way’s huge central bar, which is essentially a massive gravitational engine. The galaxy’s central bar creates its own high-pressure, high-energy environment, where stars are being born and dying, and where energetic events like supernovas happen frequently. So it’s not a nice, quiet part of the galaxy for the founding and evolution of life.

Previous studies had shown the gravitational pull of this bar served as a barrier for escaping stars. But now a new study from Tokyo Metropolitan University – and reported by EurekAlert on March 12, 2026 – suggests that, as the central bar was forming somewhere between 4 and 6 billion years ago, it triggered both star formation and a wave of outward migration for stars … maybe including our sun.

How do we know?

Assistant professors Daisuke Taniguchi at Tokyo Metropolitan University and Takuji Tsujimoto at the National Astronomical Observatory of Japan led the new studies. They looked at stars that are similar to our sun – a G-type star – in terms of temperature, composition and surface gravity. Altogether, the survey included 6,594 of these virtual twins to our sun. That was out of the overall observations of 2 billion stars.

The data came from the European Space Agency’s amazing Gaia spacecraft. Gaia did what’s called astrometry. In other words, it obtained precise measurements of the positions of stars, over and over again. In this way, it revealed the movement of stars in our galaxy for more than a decade. The data showed there was a mass movement of stars, out of the turbulent inner galactic regions to more serene pastures.

Out here, farther from our galaxy’s core and its central bar, our sun now resides in a quieter part of the galaxy. And this could have big implications for why life could arise on Earth, and possibly on planets around similar stars in our neighborhood.

The researchers published two new papers in the peer-reviewed journal Astronomy and Astrophysics on March 12, 2026.

Our current place in the Milky Way

The sun and solar system lie about 25,000 light-years from the center of the Milky Way. And the central bar in the Milky Way extends some 10,000 to 15,000 light-years from its center. The 4.6-billion-year-old sun is in the Orion-Cygnus Arm, or Orion Spur, a minor spiral arm of the Milky Way galaxy.

The new study suggests our sun began its life in the galaxy at more than 10,000 light-years nearer to the galactic center than we are today. That would have put us close to the central bar.

But the central bar has a gravitational effect that scientists call a corotation barrier. Basically, its pull of gravity makes it hard for stars to travel far away from the bar. Enter the new study. It suggests the bar wasn’t fully formed until after the sun – and thousands of similar stars – made their escape.

A graphic of the Milky Way showing our solar system’s current location in our galaxy. Note our distance from the central bar. Image via Universität Wien.

Migrating to a safer neighborhood

The scientists who conducted the new study looked at a notable concentration of stars that are around 4 to 6 billion years old, similar in age to our sun. And they all currently inhabit a region of the galaxy that’s about the same distance from the center as we are.

The scientists concluded that the age and locations of these stars are evidence of a stellar migration. They said these stars and our sun were able to escape the gravity of the still-forming bar region. The stars made a mass exodus from a region that was, coincidentally, hostile to the formation of life.

Afterward, our sun and its planets – along with thousands of similar sibling stars – came to live in a quieter galactic neighborhood. It’s a region of the Milky Way where life was able to – at least once – evolve in relative peace.

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.

A new view of the heart of the Milky Way

By the way, researchers using the Atacama Large Millimeter/submillimeter Array (ALMA) in Chile recently took a stunning new, detailed image of a molecular cloud feature in the heart of the Milky Way.

They captured the huge image in millimeter radio wavelengths. It revealed new details of a chaotic gaseous region with massive stars that orbits the supermassive black hole in our galaxy’s center. See it here, or watch the video below.

This brief video gives you a look at the new image of the Milky Way center taken in radio wavelengths. It’s the largest image the Atacama Large Millimeter/submillimeter Array (ALMA) in Chile has ever taken. Video via ALMA (ESO/ NAOJ/ NRAO)/ S. Longmore et al. Background: ESO/ D. Minniti et al.

Bottom line: A new study suggests the sun might be a migrant that was born in the inner galaxy and journeyed outward. Researchers believe it made that crossing in the company of many other stars similar to our sun.

Source: Solar twins in Gaia DR3 GSP-Spec I. Building a large catalog of solar twins with ages

Source: Solar twins in Gaia DR3 GSP-Spec II. Age distribution and its implications for the Sun’s migration

Via EurekAlert

The post Our sun might be a migrant from the inner Milky Way first appeared on EarthSky.

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A new study suggests our sun might be a migrant from a more central region of our home galaxy, the Milky Way. It suggests our sun joined a migration of other stars, which moved outward from the inner part of the galaxy some 4 to 6 billion years ago. Image via NAOJ/ EurekaAlert.

• Astronomers suggest the sun might have migrated from near the central bar-shaped nucleus of our Milky Way galaxy.
• Scientists studied 6,594 solar “twin” stars, using Gaia data. Many share the sun’s age (about 4–6 billion years) and appear to have migrated outward from the galaxy’s inner regions together.
• The sun eventually took up residence in a quieter part of the galaxy, where planets (and life) could develop with fewer threats.

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Our sun might be a migrant

Astronomers have long thought our sun was born closer to the center of our Milky Way galaxy than it is today.

The stumbling block to that idea has been the Milky Way’s huge central bar, which is essentially a massive gravitational engine. The galaxy’s central bar creates its own high-pressure, high-energy environment, where stars are being born and dying, and where energetic events like supernovas happen frequently. So it’s not a nice, quiet part of the galaxy for the founding and evolution of life.

Previous studies had shown the gravitational pull of this bar served as a barrier for escaping stars. But now a new study from Tokyo Metropolitan University – and reported by EurekAlert on March 12, 2026 – suggests that, as the central bar was forming somewhere between 4 and 6 billion years ago, it triggered both star formation and a wave of outward migration for stars … maybe including our sun.

How do we know?

Assistant professors Daisuke Taniguchi at Tokyo Metropolitan University and Takuji Tsujimoto at the National Astronomical Observatory of Japan led the new studies. They looked at stars that are similar to our sun – a G-type star – in terms of temperature, composition and surface gravity. Altogether, the survey included 6,594 of these virtual twins to our sun. That was out of the overall observations of 2 billion stars.

The data came from the European Space Agency’s amazing Gaia spacecraft. Gaia did what’s called astrometry. In other words, it obtained precise measurements of the positions of stars, over and over again. In this way, it revealed the movement of stars in our galaxy for more than a decade. The data showed there was a mass movement of stars, out of the turbulent inner galactic regions to more serene pastures.

Out here, farther from our galaxy’s core and its central bar, our sun now resides in a quieter part of the galaxy. And this could have big implications for why life could arise on Earth, and possibly on planets around similar stars in our neighborhood.

The researchers published two new papers in the peer-reviewed journal Astronomy and Astrophysics on March 12, 2026.

Our current place in the Milky Way

The sun and solar system lie about 25,000 light-years from the center of the Milky Way. And the central bar in the Milky Way extends some 10,000 to 15,000 light-years from its center. The 4.6-billion-year-old sun is in the Orion-Cygnus Arm, or Orion Spur, a minor spiral arm of the Milky Way galaxy.

The new study suggests our sun began its life in the galaxy at more than 10,000 light-years nearer to the galactic center than we are today. That would have put us close to the central bar.

But the central bar has a gravitational effect that scientists call a corotation barrier. Basically, its pull of gravity makes it hard for stars to travel far away from the bar. Enter the new study. It suggests the bar wasn’t fully formed until after the sun – and thousands of similar stars – made their escape.

A graphic of the Milky Way showing our solar system’s current location in our galaxy. Note our distance from the central bar. Image via Universität Wien.

Migrating to a safer neighborhood

The scientists who conducted the new study looked at a notable concentration of stars that are around 4 to 6 billion years old, similar in age to our sun. And they all currently inhabit a region of the galaxy that’s about the same distance from the center as we are.

The scientists concluded that the age and locations of these stars are evidence of a stellar migration. They said these stars and our sun were able to escape the gravity of the still-forming bar region. The stars made a mass exodus from a region that was, coincidentally, hostile to the formation of life.

Afterward, our sun and its planets – along with thousands of similar sibling stars – came to live in a quieter galactic neighborhood. It’s a region of the Milky Way where life was able to – at least once – evolve in relative peace.

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.

A new view of the heart of the Milky Way

By the way, researchers using the Atacama Large Millimeter/submillimeter Array (ALMA) in Chile recently took a stunning new, detailed image of a molecular cloud feature in the heart of the Milky Way.

They captured the huge image in millimeter radio wavelengths. It revealed new details of a chaotic gaseous region with massive stars that orbits the supermassive black hole in our galaxy’s center. See it here, or watch the video below.

This brief video gives you a look at the new image of the Milky Way center taken in radio wavelengths. It’s the largest image the Atacama Large Millimeter/submillimeter Array (ALMA) in Chile has ever taken. Video via ALMA (ESO/ NAOJ/ NRAO)/ S. Longmore et al. Background: ESO/ D. Minniti et al.

Bottom line: A new study suggests the sun might be a migrant that was born in the inner galaxy and journeyed outward. Researchers believe it made that crossing in the company of many other stars similar to our sun.

Source: Solar twins in Gaia DR3 GSP-Spec I. Building a large catalog of solar twins with ages

Source: Solar twins in Gaia DR3 GSP-Spec II. Age distribution and its implications for the Sun’s migration

Via EurekAlert

The post Our sun might be a migrant from the inner Milky Way first appeared on EarthSky.

from EarthSky https://ift.tt/tTPk5OS

NASA helps giant tortoises return to a Galápagos island

After 150 years, giant tortoises are back on Floreana! Watch as 158 tortoises take their first steps into the wild, guided by cutting-edge NASA data. Video via EarthSky.

You deserve a daily dose of good news. For the latest in science and the night sky, subscribe to EarthSky’s free daily newsletter.

NASA helps giant tortoises return to a Galápagos island

For the first time in more than 150 years, giant tortoises are roaming the wild again on Floreana Island in the Galápagos. On February 20, 2026, conservation teams from the Galápagos National Park Directorate and the Galápagos Conservancy released 158 tortoises at two sites. They chose those sites using NASA satellite data, identifying areas where the animals could easily find food, water and nesting locations.

Keith Gaddis, manager of NASA Earth Action’s Biological Diversity and Ecological Forecasting program, said:

This is exactly the kind of project where NASA Earth observations make a difference. We’re helping partners answer a practical question: where will these animals have the best chance to survive, not just today, but decades from now?

Giant tortoises: A history lost and found

Giant tortoises disappeared from Floreana in the mid-1800s. The Floreana giant tortoise went extinct due to a few reasons. First, sailors arrived and hunted the animals for their meat. The tortoises could be stored alive on ships for up to six months, providing fresh food in other locations. But sailors also introduced predators, such as pigs and rats, which preyed on tortoise eggs and hatchlings.

So, without the tortoises, the island began to change. Historically, giant tortoises helped shape the landscape. They grazed on vegetation, opening pathways through dense plant growth and carrying seeds.

The path to reintroduction began decades later. In 2000, James Gibbs, Vice President of Science and Conservation at the Galápagos Conservancy, and other researchers discovered unusual tortoises on Wolf Volcano in northern Isabela Island. They did not resemble any known living species.

About 10 years later, scientists compared DNA from these animals with genetic material from bones of extinct Floreana tortoises from caves and museums. The analysis confirmed some of the Wolf Volcano tortoises carried Floreana ancestry. These tortoises were a sort of hybrid. It seems as if the sailors, in moving the tortoises on their ships, at one point dropped some off on Isabela Island more than a century ago.

Scientists then used these hybrid tortoises to establish a breeding program. And it has produced hundreds of offspring that are now ready to return to Floreana.

From extinction to revival: Hybrid tortoises with Floreana ancestry are paving the way for the giant tortoise’s return to its historic island home. Image via David Liberio/ Galápagos Conservancy. Used with permission.

Matching tortoises with the right habitat

Releasing tortoises into the wild is not as simple as opening a gate. Young tortoises raised in captivity must learn to find food, water and nesting sites. Gibbs said:

They don’t know where food is; they don’t know where water is; they don’t know where to nest. If you can place them where conditions are already right, you give them a much better chance.

Floreana’s terrain adds another layer of challenge. Some hills and mountains capture clouds and support cool, moist forests. Meanwhile, lower areas remain dry most of the year. Because tortoises need both food and nesting areas, they naturally migrate between these contrasting habitats. Thanks to NASA satellite data, researchers can identify the best release sites.

This Landsat 8 image of Floreana Island from October 6, 2020, shows dry coastal lowlands surrounding greener, higher-elevation vegetation toward the island’s center. Image via Wanmei Liang/ NASA Earth Observatory.

Using NASA data to guide release of giant tortoises

NASA satellite data play a key role in understanding these movement patterns. Observations track vegetation, rainfall, moisture and land-surface temperatures across the islands. Thus, the data highlight the areas most suitable for tortoises.

The project’s team, including professor Giorgos Mountrakis at the State University of New York College, created a decision tool. It combines satellite measurements with millions of field observations of tortoise locations. The tool maps habitat suitability today and predicts conditions decades into the future. This is crucial for an animal that can live over a century. Giorgos Mountrakis said:

This isn’t a one-year project. We’re looking at where tortoises will succeed 20, 40 years from now.

The scientists used various satellites in the project. They include Landsat and European Sentinel, which monitors vegetation, the Global Precipitation Measurement mission, which provides rainfall information, and Terra, which measures land-surface temperature. Also, teams used high-resolution commercial satellite imagery from NASA’s Commercial Smallsat Data Acquisition Program. All these data allowed them to evaluate potential release sites before conducting field surveys.

Christian Sevilla, director of ecosystems at the Galápagos National Park Directorate, said:

Habitat suitability models and environmental mapping are essential tools. They allow us to integrate climate, topography and vegetation data to make evidence-based decisions. We move from intuition to precision.

This map shows modeled giant tortoise habitat suitability across the Galápagos under current environmental conditions. Colors from dark to light indicate increasing likelihood of suitable food, moisture and nesting habitat availability. Image via Wanmei Liang/ NASA Earth Observatory.

Restoring Floreana’s ecosystem

The tortoise release is part of the broader Floreana Ecological Restoration Project. This project focuses on removing invasive species such as rats and feral cats that threaten eggs and hatchlings. Eventually, the plan is that 12 native animal species will return, with giant tortoises serving as a keystone species to help rebuild ecological processes.

Over the past six decades, the Galápagos National Park Directorate has raised and released more than 10,000 tortoises across the archipelago. It’s one of the largest rewilding efforts ever attempted.

Each island presents unique challenges because of differences in vegetation, moisture and terrain. Combining long-term field observations with NASA data helps scientists anticipate how tortoises will interact with these environments. Plus, they can assess habitat changes forecast for decades ahead.

If successful, Floreana could once again support a thriving tortoise population. It could restore the interactions between animals, plants and landscapes that have shaped the island for thousands of years. Sevilla said:

For those of us who live and work in Galápagos, this release is deeply meaningful. It demonstrates that large-scale ecological restoration is possible and that, with science and long-term commitment, we can recover an essential part of the archipelago’s natural heritage.

Carrying hope on their backs: Conservation teams transport young giant tortoises to carefully chosen release sites, giving Floreana Island’s ecosystem a second chance after more than a century. Image via David Liberio/ Galápagos Conservancy. Used with permission.

Bottom line: Giant tortoises return to Floreana Island in the Galápagos. NASA satellites are guiding their release and helping revive the island’s wild ecosystem.

Via NASA

Read more: Galápagos giant tortoises migrate, albeit slowly and not too far

Read more: Sea turtles are as old as dinosaurs: Lifeform of the week

The post NASA helps giant tortoises return to a Galápagos island first appeared on EarthSky.

from EarthSky https://ift.tt/yufFtw3

After 150 years, giant tortoises are back on Floreana! Watch as 158 tortoises take their first steps into the wild, guided by cutting-edge NASA data. Video via EarthSky.

You deserve a daily dose of good news. For the latest in science and the night sky, subscribe to EarthSky’s free daily newsletter.

NASA helps giant tortoises return to a Galápagos island

For the first time in more than 150 years, giant tortoises are roaming the wild again on Floreana Island in the Galápagos. On February 20, 2026, conservation teams from the Galápagos National Park Directorate and the Galápagos Conservancy released 158 tortoises at two sites. They chose those sites using NASA satellite data, identifying areas where the animals could easily find food, water and nesting locations.

Keith Gaddis, manager of NASA Earth Action’s Biological Diversity and Ecological Forecasting program, said:

This is exactly the kind of project where NASA Earth observations make a difference. We’re helping partners answer a practical question: where will these animals have the best chance to survive, not just today, but decades from now?

Giant tortoises: A history lost and found

Giant tortoises disappeared from Floreana in the mid-1800s. The Floreana giant tortoise went extinct due to a few reasons. First, sailors arrived and hunted the animals for their meat. The tortoises could be stored alive on ships for up to six months, providing fresh food in other locations. But sailors also introduced predators, such as pigs and rats, which preyed on tortoise eggs and hatchlings.

So, without the tortoises, the island began to change. Historically, giant tortoises helped shape the landscape. They grazed on vegetation, opening pathways through dense plant growth and carrying seeds.

The path to reintroduction began decades later. In 2000, James Gibbs, Vice President of Science and Conservation at the Galápagos Conservancy, and other researchers discovered unusual tortoises on Wolf Volcano in northern Isabela Island. They did not resemble any known living species.

About 10 years later, scientists compared DNA from these animals with genetic material from bones of extinct Floreana tortoises from caves and museums. The analysis confirmed some of the Wolf Volcano tortoises carried Floreana ancestry. These tortoises were a sort of hybrid. It seems as if the sailors, in moving the tortoises on their ships, at one point dropped some off on Isabela Island more than a century ago.

Scientists then used these hybrid tortoises to establish a breeding program. And it has produced hundreds of offspring that are now ready to return to Floreana.

From extinction to revival: Hybrid tortoises with Floreana ancestry are paving the way for the giant tortoise’s return to its historic island home. Image via David Liberio/ Galápagos Conservancy. Used with permission.

Matching tortoises with the right habitat

Releasing tortoises into the wild is not as simple as opening a gate. Young tortoises raised in captivity must learn to find food, water and nesting sites. Gibbs said:

They don’t know where food is; they don’t know where water is; they don’t know where to nest. If you can place them where conditions are already right, you give them a much better chance.

Floreana’s terrain adds another layer of challenge. Some hills and mountains capture clouds and support cool, moist forests. Meanwhile, lower areas remain dry most of the year. Because tortoises need both food and nesting areas, they naturally migrate between these contrasting habitats. Thanks to NASA satellite data, researchers can identify the best release sites.

This Landsat 8 image of Floreana Island from October 6, 2020, shows dry coastal lowlands surrounding greener, higher-elevation vegetation toward the island’s center. Image via Wanmei Liang/ NASA Earth Observatory.

Using NASA data to guide release of giant tortoises

NASA satellite data play a key role in understanding these movement patterns. Observations track vegetation, rainfall, moisture and land-surface temperatures across the islands. Thus, the data highlight the areas most suitable for tortoises.

The project’s team, including professor Giorgos Mountrakis at the State University of New York College, created a decision tool. It combines satellite measurements with millions of field observations of tortoise locations. The tool maps habitat suitability today and predicts conditions decades into the future. This is crucial for an animal that can live over a century. Giorgos Mountrakis said:

This isn’t a one-year project. We’re looking at where tortoises will succeed 20, 40 years from now.

The scientists used various satellites in the project. They include Landsat and European Sentinel, which monitors vegetation, the Global Precipitation Measurement mission, which provides rainfall information, and Terra, which measures land-surface temperature. Also, teams used high-resolution commercial satellite imagery from NASA’s Commercial Smallsat Data Acquisition Program. All these data allowed them to evaluate potential release sites before conducting field surveys.

Christian Sevilla, director of ecosystems at the Galápagos National Park Directorate, said:

Habitat suitability models and environmental mapping are essential tools. They allow us to integrate climate, topography and vegetation data to make evidence-based decisions. We move from intuition to precision.

This map shows modeled giant tortoise habitat suitability across the Galápagos under current environmental conditions. Colors from dark to light indicate increasing likelihood of suitable food, moisture and nesting habitat availability. Image via Wanmei Liang/ NASA Earth Observatory.

Restoring Floreana’s ecosystem

The tortoise release is part of the broader Floreana Ecological Restoration Project. This project focuses on removing invasive species such as rats and feral cats that threaten eggs and hatchlings. Eventually, the plan is that 12 native animal species will return, with giant tortoises serving as a keystone species to help rebuild ecological processes.

Over the past six decades, the Galápagos National Park Directorate has raised and released more than 10,000 tortoises across the archipelago. It’s one of the largest rewilding efforts ever attempted.

Each island presents unique challenges because of differences in vegetation, moisture and terrain. Combining long-term field observations with NASA data helps scientists anticipate how tortoises will interact with these environments. Plus, they can assess habitat changes forecast for decades ahead.

If successful, Floreana could once again support a thriving tortoise population. It could restore the interactions between animals, plants and landscapes that have shaped the island for thousands of years. Sevilla said:

For those of us who live and work in Galápagos, this release is deeply meaningful. It demonstrates that large-scale ecological restoration is possible and that, with science and long-term commitment, we can recover an essential part of the archipelago’s natural heritage.

Carrying hope on their backs: Conservation teams transport young giant tortoises to carefully chosen release sites, giving Floreana Island’s ecosystem a second chance after more than a century. Image via David Liberio/ Galápagos Conservancy. Used with permission.

Bottom line: Giant tortoises return to Floreana Island in the Galápagos. NASA satellites are guiding their release and helping revive the island’s wild ecosystem.

Via NASA

Read more: Galápagos giant tortoises migrate, albeit slowly and not too far

Read more: Sea turtles are as old as dinosaurs: Lifeform of the week

The post NASA helps giant tortoises return to a Galápagos island first appeared on EarthSky.

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