Olbers’ paradox asks ‘Why is the night sky dark?’

Brian Jackson, Boise State University

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Why is space dark if the universe is filled with stars?

People have been asking why space is dark despite being filled with stars for so long that this question has a special name: Olbers’ paradox.

Astronomers estimate that there are about 200 billion trillion stars in the observable universe. And many of those stars are as bright or even brighter than our sun. So, why isn’t space filled with dazzling light?

I am an astronomer who studies stars and planets — including those outside our solar system — and their motion in space. The study of distant stars and planets helps astronomers like me understand why space is so dark.

You might guess it’s because a lot of the stars in the universe are very far away from Earth. Of course, it is true that the farther away a star is, the less bright it looks. A star 10 times farther away looks 100 times dimmer. But it turns out this isn’t the whole answer.

Imagine a bubble

Pretend, for a moment, that the universe is so old that the light from even the farthest stars has had time to reach Earth. In this imaginary scenario, all of the stars in the universe are not moving at all.

Picture a large bubble with Earth at the center. If the bubble were about 10 light-years across, it would contain about a dozen stars. Of course, at several light-years away, many of those stars would look pretty dim from Earth.

If you keep enlarging the bubble to 1,000 light-years across, then to one million light-years, and then one billion light-years, the farthest stars in the bubble will look even more faint. But there would also be more and more stars inside the bigger and bigger bubble, all of them contributing light. Even though the farthest stars look dimmer and dimmer, there would be a lot more of them, and the whole night sky should look very bright.

It seems I’m back where I started, but I’m actually a little closer to the answer.

Age matters in Olbers’ paradox

In the imaginary bubble illustration, I asked you to imagine that the stars are not moving and that the universe is very old. But the universe is “only” about 13 billion years old.

Even though that’s an amazingly long time in human terms, it’s short in astronomical terms. It’s short enough that the light from stars more distant than about 13 billion light-years hasn’t actually reached Earth yet. And so the actual bubble around Earth that contains all the stars we can see only extends out to about 13 billion light-years from Earth.

There just are not enough stars in the bubble to fill every line of sight. Of course, if you look in some directions in the sky, you can see stars. If you look at other bits of the sky, you can’t see any stars. And that’s because, in those dark spots, the stars that could block your line of sight are so far away their light hasn’t reached Earth yet. As time passes, light from these more and more distant stars will have time to reach us.

The Doppler shift and Olbers’ paradox

You might ask whether the night sky will eventually light up completely. But that brings me back to the other thing I told you to imagine: that all of the stars are not moving. The universe is actually expanding, with the most distant galaxies moving away from Earth at nearly the speed of light.

Because the galaxies are moving away so fast, the light from their stars is pushed into colors the human eye can’t see. This effect is the Doppler shift. So, even if it had enough time to reach you, you still couldn’t see the light from the most distant stars with your eyes. And the night sky would not be completely lit up.

If you wait even longer, eventually the stars will all burn out. Stars like the sun last only about 10 billion years. Astronomers hypothesize that in the distant future — a thousand trillion years from now — the universe will go dark, inhabited by only stellar remnants like white dwarfs and black holes.

Even though our night sky isn’t completely filled with stars, we live in a very special time in the universe’s life, when we’re lucky enough to enjoy a rich and complex night sky, filled with light and dark.

Brian Jackson, Associate Professor of Astronomy, Boise State University

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Bottom line: Olbers’ paradox asks why is space dark if the universe is filled with stars. The answer is that not all of the light from distant stars has reached us yet. Plus, the universe is expanding, so stars’ light gets red-shifted, pushing it into colors where our human eyes can’t see.

The post Olbers’ paradox asks ‘Why is the night sky dark?’ first appeared on EarthSky.

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Brian Jackson, Boise State University

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

Why is space dark if the universe is filled with stars?

People have been asking why space is dark despite being filled with stars for so long that this question has a special name: Olbers’ paradox.

Astronomers estimate that there are about 200 billion trillion stars in the observable universe. And many of those stars are as bright or even brighter than our sun. So, why isn’t space filled with dazzling light?

I am an astronomer who studies stars and planets — including those outside our solar system — and their motion in space. The study of distant stars and planets helps astronomers like me understand why space is so dark.

You might guess it’s because a lot of the stars in the universe are very far away from Earth. Of course, it is true that the farther away a star is, the less bright it looks. A star 10 times farther away looks 100 times dimmer. But it turns out this isn’t the whole answer.

Imagine a bubble

Pretend, for a moment, that the universe is so old that the light from even the farthest stars has had time to reach Earth. In this imaginary scenario, all of the stars in the universe are not moving at all.

Picture a large bubble with Earth at the center. If the bubble were about 10 light-years across, it would contain about a dozen stars. Of course, at several light-years away, many of those stars would look pretty dim from Earth.

If you keep enlarging the bubble to 1,000 light-years across, then to one million light-years, and then one billion light-years, the farthest stars in the bubble will look even more faint. But there would also be more and more stars inside the bigger and bigger bubble, all of them contributing light. Even though the farthest stars look dimmer and dimmer, there would be a lot more of them, and the whole night sky should look very bright.

It seems I’m back where I started, but I’m actually a little closer to the answer.

Age matters in Olbers’ paradox

In the imaginary bubble illustration, I asked you to imagine that the stars are not moving and that the universe is very old. But the universe is “only” about 13 billion years old.

Even though that’s an amazingly long time in human terms, it’s short in astronomical terms. It’s short enough that the light from stars more distant than about 13 billion light-years hasn’t actually reached Earth yet. And so the actual bubble around Earth that contains all the stars we can see only extends out to about 13 billion light-years from Earth.

There just are not enough stars in the bubble to fill every line of sight. Of course, if you look in some directions in the sky, you can see stars. If you look at other bits of the sky, you can’t see any stars. And that’s because, in those dark spots, the stars that could block your line of sight are so far away their light hasn’t reached Earth yet. As time passes, light from these more and more distant stars will have time to reach us.

The Doppler shift and Olbers’ paradox

You might ask whether the night sky will eventually light up completely. But that brings me back to the other thing I told you to imagine: that all of the stars are not moving. The universe is actually expanding, with the most distant galaxies moving away from Earth at nearly the speed of light.

Because the galaxies are moving away so fast, the light from their stars is pushed into colors the human eye can’t see. This effect is the Doppler shift. So, even if it had enough time to reach you, you still couldn’t see the light from the most distant stars with your eyes. And the night sky would not be completely lit up.

If you wait even longer, eventually the stars will all burn out. Stars like the sun last only about 10 billion years. Astronomers hypothesize that in the distant future — a thousand trillion years from now — the universe will go dark, inhabited by only stellar remnants like white dwarfs and black holes.

Even though our night sky isn’t completely filled with stars, we live in a very special time in the universe’s life, when we’re lucky enough to enjoy a rich and complex night sky, filled with light and dark.

Brian Jackson, Associate Professor of Astronomy, Boise State University

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Bottom line: Olbers’ paradox asks why is space dark if the universe is filled with stars. The answer is that not all of the light from distant stars has reached us yet. Plus, the universe is expanding, so stars’ light gets red-shifted, pushing it into colors where our human eyes can’t see.

The post Olbers’ paradox asks ‘Why is the night sky dark?’ first appeared on EarthSky.

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1st photo of Earth from space, 80 years ago

The 1st photo of Earth from space gave us a look at our world’s clouds from above. The image is from October 24, 1946. Image via White Sands Missile Range/ Applied Physics Laboratory/ Wikimedia Commons.

1st photo of Earth from space

On October 24, 1946, scientists launched a V-2 rocket — carrying a 35-mm motion picture camera — to a height 65 miles (105 km) above a New Mexico desert. After a few minutes, the camera dropped back to Earth and was destroyed on impact. But the film survived.

Today, the Kármán line is the widely recognized boundary that marks the edge of space. It’s located at 62 miles (100 km) above Earth’s surface, roughly where Earth’s atmosphere becomes too thin to support traditional aerodynamic flight. According to the Orbital Radar 2025 Launch Database, we’re currently launching into space at a rate of about a launch per day (6-7 launches per week).

But the 1946 first photo of Earth was nothing short of a revelation.

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

Reliving the momentous day

Air & Space Magazine tells the story of this major event in space history:

Snapping a new frame every second and a half, the rocket-borne camera climbed straight up, then fell back to Earth minutes later, slamming into the ground at 500 feet per second [152 meters/second]. The camera itself was smashed, but the film, protected in a steel cassette, was unharmed.

Fred Rulli was a 19-year-old enlisted man assigned to the recovery team that drove into the desert to retrieve film from those early V-2 shots. When the scientists found the cassette in good shape, he recalls, ‘They were ecstatic, they were jumping up and down like kids.’ Later, back at the launch site, ‘when they first projected [the photos] onto the screen, the scientists just went nuts.’

Before 1946, the highest pictures ever taken of the Earth’s surface were from the Explorer II balloon, which had ascended 13.7 miles [22 km] in 1935, high enough to discern the curvature of the Earth. The V-2 cameras reached more than five times that altitude, where they clearly showed the planet set against the blackness of space. When the movie frames were stitched together, Clyde Holliday, the engineer who developed the camera, wrote in National Geographic in 1950 that the V-2 photos showed for the first time ‘how our Earth would look to visitors from another planet coming in on a space ship.’

Another early image from space

Scientists quickly got better at taking Earth’s picture. Here’s a still frame from about 6 months later, taken from V-2 #21, launched on March 7, 1947. This picture is from 101 miles (163 km) up. The dark area on Earth at upper left is the Gulf of California. Image via White Sands Missile Range/ Naval Research Laboratory/ Wikimedia Commons.

See a panorama of Earth from 1948 here

See videos and read the rest of the story from Air & Space.

Bottom line: On October 24, 1946, a movie camera on board a V-2 rocket captured the first photo of Earth from outer space. We’ve come a long way since then!

Read more: Earth images from space: 10 incredible photos of our planet

Read more: GOES-19 first light images show stunning view of Earth

The post 1st photo of Earth from space, 80 years ago first appeared on EarthSky.

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The 1st photo of Earth from space gave us a look at our world’s clouds from above. The image is from October 24, 1946. Image via White Sands Missile Range/ Applied Physics Laboratory/ Wikimedia Commons.

1st photo of Earth from space

On October 24, 1946, scientists launched a V-2 rocket — carrying a 35-mm motion picture camera — to a height 65 miles (105 km) above a New Mexico desert. After a few minutes, the camera dropped back to Earth and was destroyed on impact. But the film survived.

Today, the Kármán line is the widely recognized boundary that marks the edge of space. It’s located at 62 miles (100 km) above Earth’s surface, roughly where Earth’s atmosphere becomes too thin to support traditional aerodynamic flight. According to the Orbital Radar 2025 Launch Database, we’re currently launching into space at a rate of about a launch per day (6-7 launches per week).

But the 1946 first photo of Earth was nothing short of a revelation.

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

Reliving the momentous day

Air & Space Magazine tells the story of this major event in space history:

Snapping a new frame every second and a half, the rocket-borne camera climbed straight up, then fell back to Earth minutes later, slamming into the ground at 500 feet per second [152 meters/second]. The camera itself was smashed, but the film, protected in a steel cassette, was unharmed.

Fred Rulli was a 19-year-old enlisted man assigned to the recovery team that drove into the desert to retrieve film from those early V-2 shots. When the scientists found the cassette in good shape, he recalls, ‘They were ecstatic, they were jumping up and down like kids.’ Later, back at the launch site, ‘when they first projected [the photos] onto the screen, the scientists just went nuts.’

Before 1946, the highest pictures ever taken of the Earth’s surface were from the Explorer II balloon, which had ascended 13.7 miles [22 km] in 1935, high enough to discern the curvature of the Earth. The V-2 cameras reached more than five times that altitude, where they clearly showed the planet set against the blackness of space. When the movie frames were stitched together, Clyde Holliday, the engineer who developed the camera, wrote in National Geographic in 1950 that the V-2 photos showed for the first time ‘how our Earth would look to visitors from another planet coming in on a space ship.’

Another early image from space

Scientists quickly got better at taking Earth’s picture. Here’s a still frame from about 6 months later, taken from V-2 #21, launched on March 7, 1947. This picture is from 101 miles (163 km) up. The dark area on Earth at upper left is the Gulf of California. Image via White Sands Missile Range/ Naval Research Laboratory/ Wikimedia Commons.

See a panorama of Earth from 1948 here

See videos and read the rest of the story from Air & Space.

Bottom line: On October 24, 1946, a movie camera on board a V-2 rocket captured the first photo of Earth from outer space. We’ve come a long way since then!

Read more: Earth images from space: 10 incredible photos of our planet

Read more: GOES-19 first light images show stunning view of Earth

The post 1st photo of Earth from space, 80 years ago first appeared on EarthSky.

from EarthSky https://ift.tt/x2n74BG

Lucy mission to Trojan asteroids: 5 years of discoveries

View larger. | Artist’s concept of the Lucy spacecraft making a close flyby of an asteroid. The Lucy mission is now less than a year from reaching the Trojan asteroids near Jupiter. Image via NASA.

• NASA’s Lucy mission is headed to the Trojan asteroids. These asteroids, traveling ahead of and behind Jupiter in its orbit, have never been explored before.
• Lucy is now less than a year away from the Trojans. But it has already made several exciting discoveries.
• These include new findings at other asteroids in the main asteroid belt between Mars and Jupiter.

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

5 years into the Lucy mission

NASA’s Lucy spacecraft is getting ever closer to its destination, the Trojan asteroids. These are two groups of asteroids that travel ahead of and behind Jupiter in its orbit. Lucy is now less than a year away from meeting its first Trojan. Exciting!

Launched on October 16, 2021, Lucy has been traveling for about five years now. But even though it hasn’t reached the asteroids yet, it has already made several remarkable discoveries, researchers from the Southwest Research Institute (SwRI) said on October 19, 2026.

Here, the white “donut” represents the main asteroid belt, between Mars and Jupiter. And the green groups of dots are Trojans. These asteroids move in Jupiter’s orbit, 60 degrees ahead of and behind the giant planet. Asteroids orbiting in front of Jupiter are named for the Greek heroes of the Trojan War. And likewise, asteroids trailing behind Jupiter are named for the Trojan heroes. Image via Wikimedia Commons.

An ambitious mission to unexplored asteroids

Lucy will be the first mission to explore the Trojan asteroids. Hal Levison at SwRI is the principal investigator of the mission. He said:

Lucy is an ambitious NASA mission, with plans to visit 11 asteroids in its 12-year mission to tour the Trojan asteroids that are located in two swarms leading and trailing Jupiter. As we passed through the main asteroid belt, we visited three asteroids, capturing close-up views of those bodies while performing engineering tests of the spacecraft’s innovative navigation system in advance of the main event to study the Trojans. These relics are effectively fossils of the planet formation process, holding vital clues to deciphering the history of our solar system.

Dinkinesh has a moon

Even though Lucy hasn’t reached the Trojans yet, it has already made several discoveries.

The first was at the asteroid Dinkinesh. Back in 2022, the mission team found that Lucy would come close to the asteroid, which was still unnamed at the time. Dinkinesh is in the main asteroid belt between Mars and Jupiter.

The flyby happened in November 2023. The mission team tweaked the spacecraft’s trajectory so it would fly even closer to Dinkinesh. And there was a surprise waiting for them.

The asteroid had a tiny moon! So now, scientists count that as being two asteroids. But there was yet another surprise.

The little moon, now named Selam, was a contact binary. That is, it had two parts that were joined together. So there were three bodies altogether, not just one.

The Lucy mission took this image a few minutes after closest approach to asteroid Dinkinesh on November 1, 2023. We clearly see the asteroid’s double moon, Selam, on the right, as 2 smaller bodies stuck together. Image via NASA/ SwRI/ Johns Hopkins APL/ NOIRLab.

Peanut-shaped Donaldjohanson

Later, in 2025, Lucy flew past another asteroid, Donaldjohanson. And this time, it was the asteroid itself that was a contact binary.

Donaldjohanson is peanut-shaped, with two large lobes joined together by a smooth “neck.” Simone Marchi, deputy principal investigator for Lucy, said:

The Donaldjohanson flyby revealed many surprises about the small asteroid. For instance, the peanut-shaped, two-lobed structure is connected by a remarkably smooth neck. The asteroid also wobbles, rotating end-over-end once every 10.5 Earth days while rolling around its lateral axis once every 26.5 days.

This is asteroid Donaldjohanson, as NASA’s Lucy spacecraft saw it during a flyby on April 20, 2025. Its apparent rotation here is due to the spacecraft’s motion as it flew by Donaldjohanson at a distance of 660 to 1,000 miles (1,060 to 1,600 km). But Lucy did find that this little asteroid wobbles in space. Image via NASA/ Goddard/ SwRI/ Johns Hopkins APL.

Gravity assists boot Lucy’s speed

During its journey, Lucy looped back and passed by Earth twice. Why? It might sound counterproductive, but the spacecraft uses Earth’s gravity to gain speed and fine-tune its trajectory.

The first gravity assist was in October 2022. Lucy passed only 220 miles (350 km) above the surface of Earth. This propelled Lucy into a two-year solar orbit. Lucy took images of Earth and the moon to calibrate its instruments.

Later, in December 2024, the second flyby increased its speed relative to the sun by over 16,000 mph (25,750 km/h). That put Lucy on a current path to make its first Trojan encounter in August 2027.

Lucy will make yet another Earth flyby in December 2030. It will then reach the second Trojan swarm of asteroids in March 2033.

NASA Lucy spacecraft’s 2nd Earth gravity assist dramatically alters the spacecraft’s trajectory, enabling it to travel through the Jupiter Trojan asteroids. Lucy’s trajectory after the assist is shown by a dashed red curve. The gray regions indicate the approximate location of the main asteroid belt (upper right) and the leading group of Jupiter trojan asteroids (lower left). In addition, the main belt asteroid Donaldjohanson and the Trojan asteroid Eurybates are shown at the time of Lucy’s encounters. Image via NASA/ SwRI.

When problems arise

With any mission, there can be problems that occur, and Lucy was no exception. Soon after launch, one of its two huge solar panels didn’t deploy properly.

However, mission engineers were able to diagnose the problem and get the solar panel to deploy far enough to save the mission.

View larger. | Lucy’s massive solar arrays completed their 1st set of deployment tests in January 2021 inside this thermal vacuum chamber at Lockheed Martin Space. NASA engineers had to solve a problem with them on the fly, as the spacecraft makes its way to the Trojan asteroids. Image via Lockheed Martin Space/ NASA.
Image via Lockheed Martin Space.

Other observations

Lucy has been fortunate to witness some other events too during its journey.

In September 2022, NASA DART probe impacted the near-Earth asteroid Didymos (on purpose, to demonstrate planetary defense technology). And Lucy saw it happen.

In September 2025, Lucy observed the now-famous interstellar comet 3I/ATLAS as it passed through our solar system. 

But there is much more to come, as Levison noted:

Despite these eventful five years, most of Lucy’s mission still lies ahead. The main events start in less than a year as Lucy gets a close-up look at four Trojan asteroid systems: Eurybates and its satellite Queta in August 2027, Polymele and its as-yet-unnamed satellite in September 2027, Leucus in April 2028 and Orus in November 2028.

It will be exciting when Lucy finally reaches the Trojans. None of them have been seen up close before, so what will Lucy find?

Bottom line: NASA’s Lucy mission is now less than a year from reaching the Trojan asteroids near Jupiter. And it has already made some exciting discoveries along the way.

Via SwRI

Read more: Lucy spacecraft 1st images of asteroid Donaldjohanson!

Read more: Lucy spacecraft update: And then there were 3!

The post Lucy mission to Trojan asteroids: 5 years of discoveries first appeared on EarthSky.

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View larger. | Artist’s concept of the Lucy spacecraft making a close flyby of an asteroid. The Lucy mission is now less than a year from reaching the Trojan asteroids near Jupiter. Image via NASA.

• NASA’s Lucy mission is headed to the Trojan asteroids. These asteroids, traveling ahead of and behind Jupiter in its orbit, have never been explored before.
• Lucy is now less than a year away from the Trojans. But it has already made several exciting discoveries.
• These include new findings at other asteroids in the main asteroid belt between Mars and Jupiter.

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

5 years into the Lucy mission

NASA’s Lucy spacecraft is getting ever closer to its destination, the Trojan asteroids. These are two groups of asteroids that travel ahead of and behind Jupiter in its orbit. Lucy is now less than a year away from meeting its first Trojan. Exciting!

Launched on October 16, 2021, Lucy has been traveling for about five years now. But even though it hasn’t reached the asteroids yet, it has already made several remarkable discoveries, researchers from the Southwest Research Institute (SwRI) said on October 19, 2026.

Here, the white “donut” represents the main asteroid belt, between Mars and Jupiter. And the green groups of dots are Trojans. These asteroids move in Jupiter’s orbit, 60 degrees ahead of and behind the giant planet. Asteroids orbiting in front of Jupiter are named for the Greek heroes of the Trojan War. And likewise, asteroids trailing behind Jupiter are named for the Trojan heroes. Image via Wikimedia Commons.

An ambitious mission to unexplored asteroids

Lucy will be the first mission to explore the Trojan asteroids. Hal Levison at SwRI is the principal investigator of the mission. He said:

Lucy is an ambitious NASA mission, with plans to visit 11 asteroids in its 12-year mission to tour the Trojan asteroids that are located in two swarms leading and trailing Jupiter. As we passed through the main asteroid belt, we visited three asteroids, capturing close-up views of those bodies while performing engineering tests of the spacecraft’s innovative navigation system in advance of the main event to study the Trojans. These relics are effectively fossils of the planet formation process, holding vital clues to deciphering the history of our solar system.

Dinkinesh has a moon

Even though Lucy hasn’t reached the Trojans yet, it has already made several discoveries.

The first was at the asteroid Dinkinesh. Back in 2022, the mission team found that Lucy would come close to the asteroid, which was still unnamed at the time. Dinkinesh is in the main asteroid belt between Mars and Jupiter.

The flyby happened in November 2023. The mission team tweaked the spacecraft’s trajectory so it would fly even closer to Dinkinesh. And there was a surprise waiting for them.

The asteroid had a tiny moon! So now, scientists count that as being two asteroids. But there was yet another surprise.

The little moon, now named Selam, was a contact binary. That is, it had two parts that were joined together. So there were three bodies altogether, not just one.

The Lucy mission took this image a few minutes after closest approach to asteroid Dinkinesh on November 1, 2023. We clearly see the asteroid’s double moon, Selam, on the right, as 2 smaller bodies stuck together. Image via NASA/ SwRI/ Johns Hopkins APL/ NOIRLab.

Peanut-shaped Donaldjohanson

Later, in 2025, Lucy flew past another asteroid, Donaldjohanson. And this time, it was the asteroid itself that was a contact binary.

Donaldjohanson is peanut-shaped, with two large lobes joined together by a smooth “neck.” Simone Marchi, deputy principal investigator for Lucy, said:

The Donaldjohanson flyby revealed many surprises about the small asteroid. For instance, the peanut-shaped, two-lobed structure is connected by a remarkably smooth neck. The asteroid also wobbles, rotating end-over-end once every 10.5 Earth days while rolling around its lateral axis once every 26.5 days.

This is asteroid Donaldjohanson, as NASA’s Lucy spacecraft saw it during a flyby on April 20, 2025. Its apparent rotation here is due to the spacecraft’s motion as it flew by Donaldjohanson at a distance of 660 to 1,000 miles (1,060 to 1,600 km). But Lucy did find that this little asteroid wobbles in space. Image via NASA/ Goddard/ SwRI/ Johns Hopkins APL.

Gravity assists boot Lucy’s speed

During its journey, Lucy looped back and passed by Earth twice. Why? It might sound counterproductive, but the spacecraft uses Earth’s gravity to gain speed and fine-tune its trajectory.

The first gravity assist was in October 2022. Lucy passed only 220 miles (350 km) above the surface of Earth. This propelled Lucy into a two-year solar orbit. Lucy took images of Earth and the moon to calibrate its instruments.

Later, in December 2024, the second flyby increased its speed relative to the sun by over 16,000 mph (25,750 km/h). That put Lucy on a current path to make its first Trojan encounter in August 2027.

Lucy will make yet another Earth flyby in December 2030. It will then reach the second Trojan swarm of asteroids in March 2033.

NASA Lucy spacecraft’s 2nd Earth gravity assist dramatically alters the spacecraft’s trajectory, enabling it to travel through the Jupiter Trojan asteroids. Lucy’s trajectory after the assist is shown by a dashed red curve. The gray regions indicate the approximate location of the main asteroid belt (upper right) and the leading group of Jupiter trojan asteroids (lower left). In addition, the main belt asteroid Donaldjohanson and the Trojan asteroid Eurybates are shown at the time of Lucy’s encounters. Image via NASA/ SwRI.

When problems arise

With any mission, there can be problems that occur, and Lucy was no exception. Soon after launch, one of its two huge solar panels didn’t deploy properly.

However, mission engineers were able to diagnose the problem and get the solar panel to deploy far enough to save the mission.

View larger. | Lucy’s massive solar arrays completed their 1st set of deployment tests in January 2021 inside this thermal vacuum chamber at Lockheed Martin Space. NASA engineers had to solve a problem with them on the fly, as the spacecraft makes its way to the Trojan asteroids. Image via Lockheed Martin Space/ NASA.
Image via Lockheed Martin Space.

Other observations

Lucy has been fortunate to witness some other events too during its journey.

In September 2022, NASA DART probe impacted the near-Earth asteroid Didymos (on purpose, to demonstrate planetary defense technology). And Lucy saw it happen.

In September 2025, Lucy observed the now-famous interstellar comet 3I/ATLAS as it passed through our solar system. 

But there is much more to come, as Levison noted:

Despite these eventful five years, most of Lucy’s mission still lies ahead. The main events start in less than a year as Lucy gets a close-up look at four Trojan asteroid systems: Eurybates and its satellite Queta in August 2027, Polymele and its as-yet-unnamed satellite in September 2027, Leucus in April 2028 and Orus in November 2028.

It will be exciting when Lucy finally reaches the Trojans. None of them have been seen up close before, so what will Lucy find?

Bottom line: NASA’s Lucy mission is now less than a year from reaching the Trojan asteroids near Jupiter. And it has already made some exciting discoveries along the way.

Via SwRI

Read more: Lucy spacecraft 1st images of asteroid Donaldjohanson!

Read more: Lucy spacecraft update: And then there were 3!

The post Lucy mission to Trojan asteroids: 5 years of discoveries first appeared on EarthSky.

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Cassiopeia and Perseus on October evenings

You can find Perseus with the help of the constellation Cassiopeia the Queen. Cassiopeia’s distinctive M or W shape is ascending in the northeast on Northern Hemisphere autumn evenings, with Perseus following. Cassiopeia and Perseus travel together in a great arc around the northern sky. Be sure to look for the star Algol, sometimes called the Ghoul Star or Demon Star … a perfect star for the Halloween month!

If you know how to locate the easy-to-spot constellation Cassiopeia the Queen, with its distinctive M or W shape, then you’re ready to find Perseus. Perseus the Hero follows Cassiopeia across the sky as seen from the Northern Hemisphere on autumn and winter evenings. Cassiopeia and Perseus are tokens of autumn in the Northern Hemisphere.

Cassiopeia’s bright stars and easy-to-recognize shape makes it easy to identify and, therefore, one of the most famous constellations in the sky.

Perseus’s stars are fainter than Cassiopeia’s, and its shape is less pronounced. Because it appears at its best during the evening on cold months, I think of its brightest stars as forming an icicle dangling down from Cassiopeia, with the star Algol off to the side. If you have access to a dark sky, it will be that much easier to spot Perseus.

In skylore and mythology, Perseus beheaded Medusa, a witch who had snakes for hair. This image is from Urania’s Mirror, a set of constellation cards published in London around 1825. Image via Wikimedia Commons (public domain).

Where to find Cassiopeia and Perseus

You’ll see both Cassiopeia and Perseus in the northeast on October evenings. The pair will be higher up in the evening sky in late autumn and winter. Or, as night passes, you’ll see them both ascending in the northeast, then arcing high in the north, then descending in the northwest, with Perseus following Cassiopeia all the while.

Both Perseus and Cassiopeia are circumpolar from about 40 degrees north latitude to farther north. In other words, as seen from northern parts of the U.S. and Canada, they never set below the horizon, but instead circle endlessly around Polaris, the North Star.

The brightest star in Cassiopeia is Schedar. However, all the stars shine at a similar brightness, which is part of what makes the constellation so easy to pick out.

The brightest star in Perseus is Mirfak. But its second brightest star, Algol, gets more attention. Algol is known as the Demon Star. It marks the head of the demon Medusa, and it’s also a variable star. That means it varies in brightness at a regular rate, every few days, which observers can watch without the need for optical aid.

The radiant for the Perseids

Although these constellations are best seen in the evening in autumn and winter, you can also see Cassiopeia and Perseus in the latter part of Northern Hemisphere summer, from late night until dawn.

Plus, the annual Perseid meteor shower peaks around August 12 or 13, and if you trace the paths of these Perseid meteors backward, they’ll appear to originate between the two constellations.

The annual Perseid meteors radiate from a point in the constellation Perseus the Hero. In August, the radiant rises in late evening and is highest at dawn.

The Double Cluster in Perseus

Last, but not least, after you’ve found Cassiopeia and Perseus, be sure to scan between them with your binoculars. Assuming your sky is dark, you’ll easily spot the magnificent Double Cluster in Perseus. This pair of open clusters makes for an easy target through a telescope and will wow your friends.

View at EarthSky Community Photos. | David Hoskin in Halifax, Nova Scotia, Canada, captured the Double Cluster on September 4, 2024. David wrote: “Open star clusters NGC 884 and NGC 869 together are referred to as the Double Cluster. Located in Perseus, you can see these beautiful open star clusters with the unaided eye. Both open star clusters are relatively young at 14 million years and are about 7,500 light-years from Earth.” Thank you, David!

View at EarthSky Community Photos. | Jeremy Likness in Newport, Oregon, captured this telescopic view of the Double Cluster in the constellation Perseus on November 24, 2023. Jeremy wrote: “The Double Cluster is the beautiful pair of NGC 869 (h Persei) and NGC 884 (Chi Persei). They contain over 300 blue-white supergiants and a scattering of red supergiants. The cluster is also blue-shifted as it inches its way 24 miles closer [39 km] to Earth every second. It is visible to the unaided eye and lurks near the distinct ‘W’ of Cassiopeia.” Thank you, Jeremy!

Bottom line: Cassiopeia and Perseus are neighbors in the fall sky. Use Cassiopeia’s distinctive W or M shape to locate the dimmer Perseus on autumn and winter evenings.

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You can find Perseus with the help of the constellation Cassiopeia the Queen. Cassiopeia’s distinctive M or W shape is ascending in the northeast on Northern Hemisphere autumn evenings, with Perseus following. Cassiopeia and Perseus travel together in a great arc around the northern sky. Be sure to look for the star Algol, sometimes called the Ghoul Star or Demon Star … a perfect star for the Halloween month!

If you know how to locate the easy-to-spot constellation Cassiopeia the Queen, with its distinctive M or W shape, then you’re ready to find Perseus. Perseus the Hero follows Cassiopeia across the sky as seen from the Northern Hemisphere on autumn and winter evenings. Cassiopeia and Perseus are tokens of autumn in the Northern Hemisphere.

Cassiopeia’s bright stars and easy-to-recognize shape makes it easy to identify and, therefore, one of the most famous constellations in the sky.

Perseus’s stars are fainter than Cassiopeia’s, and its shape is less pronounced. Because it appears at its best during the evening on cold months, I think of its brightest stars as forming an icicle dangling down from Cassiopeia, with the star Algol off to the side. If you have access to a dark sky, it will be that much easier to spot Perseus.

In skylore and mythology, Perseus beheaded Medusa, a witch who had snakes for hair. This image is from Urania’s Mirror, a set of constellation cards published in London around 1825. Image via Wikimedia Commons (public domain).

Where to find Cassiopeia and Perseus

You’ll see both Cassiopeia and Perseus in the northeast on October evenings. The pair will be higher up in the evening sky in late autumn and winter. Or, as night passes, you’ll see them both ascending in the northeast, then arcing high in the north, then descending in the northwest, with Perseus following Cassiopeia all the while.

Both Perseus and Cassiopeia are circumpolar from about 40 degrees north latitude to farther north. In other words, as seen from northern parts of the U.S. and Canada, they never set below the horizon, but instead circle endlessly around Polaris, the North Star.

The brightest star in Cassiopeia is Schedar. However, all the stars shine at a similar brightness, which is part of what makes the constellation so easy to pick out.

The brightest star in Perseus is Mirfak. But its second brightest star, Algol, gets more attention. Algol is known as the Demon Star. It marks the head of the demon Medusa, and it’s also a variable star. That means it varies in brightness at a regular rate, every few days, which observers can watch without the need for optical aid.

The radiant for the Perseids

Although these constellations are best seen in the evening in autumn and winter, you can also see Cassiopeia and Perseus in the latter part of Northern Hemisphere summer, from late night until dawn.

Plus, the annual Perseid meteor shower peaks around August 12 or 13, and if you trace the paths of these Perseid meteors backward, they’ll appear to originate between the two constellations.

The annual Perseid meteors radiate from a point in the constellation Perseus the Hero. In August, the radiant rises in late evening and is highest at dawn.

The Double Cluster in Perseus

Last, but not least, after you’ve found Cassiopeia and Perseus, be sure to scan between them with your binoculars. Assuming your sky is dark, you’ll easily spot the magnificent Double Cluster in Perseus. This pair of open clusters makes for an easy target through a telescope and will wow your friends.

View at EarthSky Community Photos. | David Hoskin in Halifax, Nova Scotia, Canada, captured the Double Cluster on September 4, 2024. David wrote: “Open star clusters NGC 884 and NGC 869 together are referred to as the Double Cluster. Located in Perseus, you can see these beautiful open star clusters with the unaided eye. Both open star clusters are relatively young at 14 million years and are about 7,500 light-years from Earth.” Thank you, David!

View at EarthSky Community Photos. | Jeremy Likness in Newport, Oregon, captured this telescopic view of the Double Cluster in the constellation Perseus on November 24, 2023. Jeremy wrote: “The Double Cluster is the beautiful pair of NGC 869 (h Persei) and NGC 884 (Chi Persei). They contain over 300 blue-white supergiants and a scattering of red supergiants. The cluster is also blue-shifted as it inches its way 24 miles closer [39 km] to Earth every second. It is visible to the unaided eye and lurks near the distinct ‘W’ of Cassiopeia.” Thank you, Jeremy!

Bottom line: Cassiopeia and Perseus are neighbors in the fall sky. Use Cassiopeia’s distinctive W or M shape to locate the dimmer Perseus on autumn and winter evenings.

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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Euclid was mapping the universe. Then it found a comet

The Euclid space telescope made an accidental comet discovery as it searched the universe for evidence of dark matter and dark energy. Euclid took these images at 00:41:07, 00:58:53 and 01:16:39 UTC on September 17, 2026. The comet is now named C/2026 S1 (Euclid). Animation via ESA/ Euclid/ Euclid Consortium/ NASA, M. Pöntinen et al. 2026.

Euclid makes an accidental comet discovery

ESA’s Euclid space telescope is surveying the cosmos, mapping the large-scale structure of the universe in space and time. Its goal is to observe more than 1/3 of the sky, concentrating on how galaxies have evolved over time, in the hopes of providing insight to the nature of dark matter and dark energy. But ESA said on October 19, 2026, that Euclid has made an unexpected discovery, and a first for the space telescope. It spotted a comet some 800 million miles (1.3 billion km) away in our solar system.

The Minor Planet Center named the comet C/2026 S1 (Euclid) in honor of the space telescope. The comet lies somewhere between Jupiter and Saturn’s orbits. Only it’s not in the plane of our solar system with the other planets, asteroids and comets at all. Instead, it’s approximately straight up from the sun’s perspective.

Euclid caught the comet whizzing by background galaxies. Despite its high rate of speed, the comet will still take thousands of years to complete one orbit of the sun.

Finding the streaking fuzzy cloud

Mikko Pöntinen of the University of Helsinki discovered the comet using object-detection software. Pöntinen said:

I was excited to see my software flag a ‘streak’ smeared across several images — the result of a fast-moving object. By predicting its position I could identify it in other images, in total finding it in five image sets. Further inspection revealed that it had a fuzzy cloud around it, indicative of an active object like a comet that is shedding dust and gas.

The space telescope was imaging the Euclid Deep Field North at the time of capture. In the image above, you can see the background galaxies in the field of view as the comet suddenly streaks by. Euclid took those images between September 16 and 24, 2026. The Minor Planet Center confirmed the discovery of the new comet on October 8, 2026.

Euclid intentionally looks away from the solar system’s plane to reduce glare from dust leftover from the creation of planets and asteroids.

Bruno Altieri, Euclid archive scientist and part of the discovery team, said:

Very few comets are expected to be discovered by Euclid so it was a happy coincidence that the combination of the comet’s orbit and Euclid’s scanning over those days captured the object in multiple images.

Finding future targets of the Comet Interceptor

ESA is planning a future mission called Comet Interceptor. The mission will park itself in space and await a target that is not from the plane of our solar system, but one that is pristine and untouched from the outer reaches of the sun’s realm. And now, researchers think Euclid could help Comet Interceptor find a comet to target.

Valeria Pettorino, Euclid project scientist, said:

While this particular comet is not a suitable candidate for Comet Interceptor, the process of discovery and alert gives us a real test case for how our two mission teams will coordinate in the future. And we are of course happy to have discovered a previously unknown comet for the solar system community to follow-up on.

Comet C/2026 S1 (Euclid) in a wide image (left), with the inset focusing on just the comet (right). It appears as a streak because it moved over the course of the long exposure. Image via ESA/ Euclid/ Euclid Consortium/ NASA/ M. Pöntinen et al. 2026.

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

Bottom line: The Euclid space telescope made an accidental comet discovery as it searched the universe for evidence of dark matter and dark energy. The comet is now named C/2026 S1 (Euclid). 

Read more: Euclid finds the most ancient quasars in the universe so far

Read more: New Euclid images reveal hidden gravitational lenses

The post Euclid was mapping the universe. Then it found a comet first appeared on EarthSky.

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The Euclid space telescope made an accidental comet discovery as it searched the universe for evidence of dark matter and dark energy. Euclid took these images at 00:41:07, 00:58:53 and 01:16:39 UTC on September 17, 2026. The comet is now named C/2026 S1 (Euclid). Animation via ESA/ Euclid/ Euclid Consortium/ NASA, M. Pöntinen et al. 2026.

Euclid makes an accidental comet discovery

ESA’s Euclid space telescope is surveying the cosmos, mapping the large-scale structure of the universe in space and time. Its goal is to observe more than 1/3 of the sky, concentrating on how galaxies have evolved over time, in the hopes of providing insight to the nature of dark matter and dark energy. But ESA said on October 19, 2026, that Euclid has made an unexpected discovery, and a first for the space telescope. It spotted a comet some 800 million miles (1.3 billion km) away in our solar system.

The Minor Planet Center named the comet C/2026 S1 (Euclid) in honor of the space telescope. The comet lies somewhere between Jupiter and Saturn’s orbits. Only it’s not in the plane of our solar system with the other planets, asteroids and comets at all. Instead, it’s approximately straight up from the sun’s perspective.

Euclid caught the comet whizzing by background galaxies. Despite its high rate of speed, the comet will still take thousands of years to complete one orbit of the sun.

Finding the streaking fuzzy cloud

Mikko Pöntinen of the University of Helsinki discovered the comet using object-detection software. Pöntinen said:

I was excited to see my software flag a ‘streak’ smeared across several images — the result of a fast-moving object. By predicting its position I could identify it in other images, in total finding it in five image sets. Further inspection revealed that it had a fuzzy cloud around it, indicative of an active object like a comet that is shedding dust and gas.

The space telescope was imaging the Euclid Deep Field North at the time of capture. In the image above, you can see the background galaxies in the field of view as the comet suddenly streaks by. Euclid took those images between September 16 and 24, 2026. The Minor Planet Center confirmed the discovery of the new comet on October 8, 2026.

Euclid intentionally looks away from the solar system’s plane to reduce glare from dust leftover from the creation of planets and asteroids.

Bruno Altieri, Euclid archive scientist and part of the discovery team, said:

Very few comets are expected to be discovered by Euclid so it was a happy coincidence that the combination of the comet’s orbit and Euclid’s scanning over those days captured the object in multiple images.

Finding future targets of the Comet Interceptor

ESA is planning a future mission called Comet Interceptor. The mission will park itself in space and await a target that is not from the plane of our solar system, but one that is pristine and untouched from the outer reaches of the sun’s realm. And now, researchers think Euclid could help Comet Interceptor find a comet to target.

Valeria Pettorino, Euclid project scientist, said:

While this particular comet is not a suitable candidate for Comet Interceptor, the process of discovery and alert gives us a real test case for how our two mission teams will coordinate in the future. And we are of course happy to have discovered a previously unknown comet for the solar system community to follow-up on.

Comet C/2026 S1 (Euclid) in a wide image (left), with the inset focusing on just the comet (right). It appears as a streak because it moved over the course of the long exposure. Image via ESA/ Euclid/ Euclid Consortium/ NASA/ M. Pöntinen et al. 2026.

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

Bottom line: The Euclid space telescope made an accidental comet discovery as it searched the universe for evidence of dark matter and dark energy. The comet is now named C/2026 S1 (Euclid). 

Read more: Euclid finds the most ancient quasars in the universe so far

Read more: New Euclid images reveal hidden gravitational lenses

The post Euclid was mapping the universe. Then it found a comet first appeared on EarthSky.

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Pegasus is a baseball diamond! Just in time for the World Series

The Great Square of Pegasus can appear as a diamond shape depending on its orientation in the sky. On the evenings of October 23 and 24, the gibbous moon will shine below it. Also, look for the steady, golden light of the planet Saturn nearby. Chart via EarthSky.

Almost out of nowhere, the summer skies have become the autumn skies. And, with that, here we are in the meat of baseball’s playoffs. One of the things I love most about this time of year is how, almost to celebrate baseball’s holy month, the skies bring us a mighty interstellar baseball diamond.

This weekend, after you’ve finished trying to find Saturn as it hides among the eastern sky’s stars, turn a bit to the left. As darkness falls, you’ll see a huge square of four stars rising into the eastern skies.

“Wait. That’s the Great Square of Pegasus. What does that have to do with baseball?”

Well … baseball’s played on a diamond, right? And what’s a diamond if not a square turned 45 degrees? As mid-October and the playoffs come along, the Great Square sits over the horizon with home plate at the bottom. Second base sits higher above, about halfway toward Vega and Deneb, which you might remember from such asterisms as the out-of-season Summer Triangle.

Over time, the diamond will turn and square itself out. But for now, there’s a game of astro-baseball (spaceball?) happening somewhere out there.

The stars of the Great Diamond

The points of this diamond are 2nd- and 3rd-magnitude stars a couple hundred light-years away. Behind the plate is Algenib, an old star about five times the size of our sun. Then, heading around the horn, are Markab at first, and the red giant Scheat is at second.

At the hot corner is the beautiful Alpheratz, about 100 light-years away. Oh, Alpheratz. Even though its name comes from Arabic and means something like the horse’s navel, it’s actually not in Pegasus at all, but in Andromeda, right on the border. In fact, for many years, it was considered part of both constellations.

I really love that star. For me, there’s something about it that really makes me happy. Maybe it’s its muted, far-off, icy color, or maybe it’s that I use it to find the great Andromeda Galaxy in my binoculars. With a good view of that part of the sky, you can see a line of three stars extending from the Great Square Baseball Diamond off toward the northwest. That’s the rest of Andromeda the Chained Lady. And that constellation is home to the Andromeda Galaxy, or Messier 31, just a couple million light-years away.

Make the sky your own

Many years ago, long before I learned much about the constellations, I stood staring out the window. The Brewers were playing the Cardinals in the World Series on the TV behind me. I loved baseball, still do, but I was a Yankees fan, still am. So, when Robin Yount and Ozzie Smith weren’t batting, I was a little bored. I stared and noticed those stars and made my own asterism out of them. That’s one of the things I love most about watching the skies. We can all turn out the lights, look away from the news, and make it our own.

After all these years, it’s fun to sit here and think of myself in 1982. It’s fun to still see those stars and think of them as a baseball diamond. It’s fun to think of where I was then and where I am now, here, writing about it.

Maybe this weekend, grab a baseball-obsessed kid, head out, and show them the most gigantic baseball diamond in the universe, too.

Don’t miss the next unmissable night sky event. Sign up to EarthSky’s free newsletter for daily night sky updates.

Bottom line: Pegasus is a baseball diamond! And you can see it, too. The Great Square of Pegasus is tilted to look like a diamond in October, as if to celebrate the World Series.

Read more: Pegasus the Flying Horse, and the best sky story ever

Read more: Great Square of Pegasus gallops into the autumn sky

The post Pegasus is a baseball diamond! Just in time for the World Series first appeared on EarthSky.

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The Great Square of Pegasus can appear as a diamond shape depending on its orientation in the sky. On the evenings of October 23 and 24, the gibbous moon will shine below it. Also, look for the steady, golden light of the planet Saturn nearby. Chart via EarthSky.

Almost out of nowhere, the summer skies have become the autumn skies. And, with that, here we are in the meat of baseball’s playoffs. One of the things I love most about this time of year is how, almost to celebrate baseball’s holy month, the skies bring us a mighty interstellar baseball diamond.

This weekend, after you’ve finished trying to find Saturn as it hides among the eastern sky’s stars, turn a bit to the left. As darkness falls, you’ll see a huge square of four stars rising into the eastern skies.

“Wait. That’s the Great Square of Pegasus. What does that have to do with baseball?”

Well … baseball’s played on a diamond, right? And what’s a diamond if not a square turned 45 degrees? As mid-October and the playoffs come along, the Great Square sits over the horizon with home plate at the bottom. Second base sits higher above, about halfway toward Vega and Deneb, which you might remember from such asterisms as the out-of-season Summer Triangle.

Over time, the diamond will turn and square itself out. But for now, there’s a game of astro-baseball (spaceball?) happening somewhere out there.

The stars of the Great Diamond

The points of this diamond are 2nd- and 3rd-magnitude stars a couple hundred light-years away. Behind the plate is Algenib, an old star about five times the size of our sun. Then, heading around the horn, are Markab at first, and the red giant Scheat is at second.

At the hot corner is the beautiful Alpheratz, about 100 light-years away. Oh, Alpheratz. Even though its name comes from Arabic and means something like the horse’s navel, it’s actually not in Pegasus at all, but in Andromeda, right on the border. In fact, for many years, it was considered part of both constellations.

I really love that star. For me, there’s something about it that really makes me happy. Maybe it’s its muted, far-off, icy color, or maybe it’s that I use it to find the great Andromeda Galaxy in my binoculars. With a good view of that part of the sky, you can see a line of three stars extending from the Great Square Baseball Diamond off toward the northwest. That’s the rest of Andromeda the Chained Lady. And that constellation is home to the Andromeda Galaxy, or Messier 31, just a couple million light-years away.

Make the sky your own

Many years ago, long before I learned much about the constellations, I stood staring out the window. The Brewers were playing the Cardinals in the World Series on the TV behind me. I loved baseball, still do, but I was a Yankees fan, still am. So, when Robin Yount and Ozzie Smith weren’t batting, I was a little bored. I stared and noticed those stars and made my own asterism out of them. That’s one of the things I love most about watching the skies. We can all turn out the lights, look away from the news, and make it our own.

After all these years, it’s fun to sit here and think of myself in 1982. It’s fun to still see those stars and think of them as a baseball diamond. It’s fun to think of where I was then and where I am now, here, writing about it.

Maybe this weekend, grab a baseball-obsessed kid, head out, and show them the most gigantic baseball diamond in the universe, too.

Don’t miss the next unmissable night sky event. Sign up to EarthSky’s free newsletter for daily night sky updates.

Bottom line: Pegasus is a baseball diamond! And you can see it, too. The Great Square of Pegasus is tilted to look like a diamond in October, as if to celebrate the World Series.

Read more: Pegasus the Flying Horse, and the best sky story ever

Read more: Great Square of Pegasus gallops into the autumn sky

The post Pegasus is a baseball diamond! Just in time for the World Series first appeared on EarthSky.

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Auriga the Charioteer and bright Capella on October evenings

Auriga the Charioteer is a popular constellation on northern autumn evenings. That’s because its flashing star advertises its presence. Capella, the brightest star in Auriga, flashes red, blue and green when it’s close to the horizon. Watch this video for more info.

Auriga has a flashy star and 3 star clusters

Auriga the Charioteer is a popular constellation for Northern Hemisphere observers in autumn, because its flashing star advertises its presence. Capella, the brightest star in Auriga, flashes red, blue and green when it’s close to the horizon and seen through a thick layer of Earth’s atmosphere.

Close to Capella are a pair of stars known as The Kids, baby goats that the Charioteer carries. And Auriga houses three star clusters, easy targets to hunt down with binoculars.

Auriga is a far-northern constellation. It’s close enough to the North Star that people in the northern U.S. and Canada – and similar latitudes – see it as circumpolar. In other words, they can see all or part of the constellation on any night of the year.

But some times of the year are better than others. If you want to see the entirety of Auriga, start looking for the constellation and flickering Capella in Northern Hemisphere autumn. Soon you’ll be familiar with its gems and ready to go deeper by the time it moves higher and into better viewing position by winter.

The bright star Capella in the constellation Auriga the Charioteer is our #1 choice for flashiest star on October evenings. That’s because Capella is bright, at magnitude 0.8. And it’s low in the sky, in the northeast direction as seen from the Northern Hemisphere, in the evening at this time of the year. To be sure you’ve found Capella, look for a little triangle of stars nearby. Capella is sometimes called the Goat Star, and this little asterism is called The Kids.

Auriga the Charioteer’s brightest star, Capella

Auriga’s brightest star, Alpha Aurigae, is a twinkling beauty named Capella. It’s a golden star, somewhat similar to our sun. In fact, if you could get some distance away from our solar system – light-years away – you might see our sun much as we see Capella.

Capella is located at one corner of the constellation Auriga, marking the Charioteer’s left shoulder. By the way, Capella has the nickname the Goat Star.

Capella garners a lot of attention on autumn evenings in the Northern Hemisphere because we see it near the horizon through a thick layer of Earth’s atmosphere. The wavering atmosphere causes the light from the star to jump around, flashing bright colors of red, green and blue, making it look like an emergency vehicle parked in space.

On winter evenings, Capella moves overhead near zenith and its flashiness is dampened as we look at it through a thinner layer of atmosphere.

Capella shines at a magnitude of 0.08 and is the 6th brightest star in the sky. It’s so bright because it’s nearby. Capella lies just 43 light-years away. This star marks one of the corners of the Winter Circle.

In fact, Capella is actually a pair of binary stars, both of which are yellow giant stars with small red dwarf companions.

Capella is also the closest 1st magnitude star to Polaris, the star currently marking our north celestial pole.

Auriga carrying the Goat and Kids as depicted in Urania’s Mirror, a set of constellation cards published in London circa 1825. Image via Wikipedia (public domain).

The asterism of The Kids

If you’re unsure whether you’ve identified Capella, you can always look nearby for a small triangle of stars. This triangle is an asterism, or a smaller named configuration of stars. While Capella is the Goat Star, this little triangle asterism represents The Kids. Learn more about Auriga and The Kids.

Other stars in Auriga the Charioteer

Menkalinan, the second brightest star in Auriga, marks the Charioteer’s right shoulder. This star is also fairly nearby, at a distance of 85 light-years.

Notice the star Elnath at the southern tip of Auriga. This star used to belong both to Auriga, where it was known as the heel of the Charioteer, and to the constellation Taurus the Bull, where it represented the tip of the Bull’s northern horn. In the last century, though, the International Astronomical Union decreed that this star shall belong only to Taurus!

Star clusters in Auriga the Charioteer

In a dark sky, using binoculars, you can spot some easy-to-see star clusters within Auriga: M36, M37 and M38. These Messier objects fall nearly in a line with M36 in the middle. The open star clusters have distinct personalities when viewed with magnification.

M36 bears the nickname the Pinwheel cluster and looks reminiscent of the Pleiades. M37 is the brightest and largest of the three clusters and lies opposite the Milky Way‘s galactic center, still in the plane of our galaxy but looking out to its fringes. Lastly, M38 has the nickname the Starfish cluster. Others think this cluster looks like an X or the Greek letter Pi. What do you see?

The constellation Auriga the Charioteer. Image via Wikimedia.

Bottom line: From the Northern Hemisphere, look for the beautiful star Capella and its constellation Auriga the Charioteer.

Flashing stars in autumn? Here are 3 candidates

Messier objects are fuzzy patches in the night sky

Polaris is the present-day North Star of Earth

The post Auriga the Charioteer and bright Capella on October evenings first appeared on EarthSky.

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Auriga the Charioteer is a popular constellation on northern autumn evenings. That’s because its flashing star advertises its presence. Capella, the brightest star in Auriga, flashes red, blue and green when it’s close to the horizon. Watch this video for more info.

Auriga has a flashy star and 3 star clusters

Auriga the Charioteer is a popular constellation for Northern Hemisphere observers in autumn, because its flashing star advertises its presence. Capella, the brightest star in Auriga, flashes red, blue and green when it’s close to the horizon and seen through a thick layer of Earth’s atmosphere.

Close to Capella are a pair of stars known as The Kids, baby goats that the Charioteer carries. And Auriga houses three star clusters, easy targets to hunt down with binoculars.

Auriga is a far-northern constellation. It’s close enough to the North Star that people in the northern U.S. and Canada – and similar latitudes – see it as circumpolar. In other words, they can see all or part of the constellation on any night of the year.

But some times of the year are better than others. If you want to see the entirety of Auriga, start looking for the constellation and flickering Capella in Northern Hemisphere autumn. Soon you’ll be familiar with its gems and ready to go deeper by the time it moves higher and into better viewing position by winter.

The bright star Capella in the constellation Auriga the Charioteer is our #1 choice for flashiest star on October evenings. That’s because Capella is bright, at magnitude 0.8. And it’s low in the sky, in the northeast direction as seen from the Northern Hemisphere, in the evening at this time of the year. To be sure you’ve found Capella, look for a little triangle of stars nearby. Capella is sometimes called the Goat Star, and this little asterism is called The Kids.

Auriga the Charioteer’s brightest star, Capella

Auriga’s brightest star, Alpha Aurigae, is a twinkling beauty named Capella. It’s a golden star, somewhat similar to our sun. In fact, if you could get some distance away from our solar system – light-years away – you might see our sun much as we see Capella.

Capella is located at one corner of the constellation Auriga, marking the Charioteer’s left shoulder. By the way, Capella has the nickname the Goat Star.

Capella garners a lot of attention on autumn evenings in the Northern Hemisphere because we see it near the horizon through a thick layer of Earth’s atmosphere. The wavering atmosphere causes the light from the star to jump around, flashing bright colors of red, green and blue, making it look like an emergency vehicle parked in space.

On winter evenings, Capella moves overhead near zenith and its flashiness is dampened as we look at it through a thinner layer of atmosphere.

Capella shines at a magnitude of 0.08 and is the 6th brightest star in the sky. It’s so bright because it’s nearby. Capella lies just 43 light-years away. This star marks one of the corners of the Winter Circle.

In fact, Capella is actually a pair of binary stars, both of which are yellow giant stars with small red dwarf companions.

Capella is also the closest 1st magnitude star to Polaris, the star currently marking our north celestial pole.

Auriga carrying the Goat and Kids as depicted in Urania’s Mirror, a set of constellation cards published in London circa 1825. Image via Wikipedia (public domain).

The asterism of The Kids

If you’re unsure whether you’ve identified Capella, you can always look nearby for a small triangle of stars. This triangle is an asterism, or a smaller named configuration of stars. While Capella is the Goat Star, this little triangle asterism represents The Kids. Learn more about Auriga and The Kids.

Other stars in Auriga the Charioteer

Menkalinan, the second brightest star in Auriga, marks the Charioteer’s right shoulder. This star is also fairly nearby, at a distance of 85 light-years.

Notice the star Elnath at the southern tip of Auriga. This star used to belong both to Auriga, where it was known as the heel of the Charioteer, and to the constellation Taurus the Bull, where it represented the tip of the Bull’s northern horn. In the last century, though, the International Astronomical Union decreed that this star shall belong only to Taurus!

Star clusters in Auriga the Charioteer

In a dark sky, using binoculars, you can spot some easy-to-see star clusters within Auriga: M36, M37 and M38. These Messier objects fall nearly in a line with M36 in the middle. The open star clusters have distinct personalities when viewed with magnification.

M36 bears the nickname the Pinwheel cluster and looks reminiscent of the Pleiades. M37 is the brightest and largest of the three clusters and lies opposite the Milky Way‘s galactic center, still in the plane of our galaxy but looking out to its fringes. Lastly, M38 has the nickname the Starfish cluster. Others think this cluster looks like an X or the Greek letter Pi. What do you see?

The constellation Auriga the Charioteer. Image via Wikimedia.

Bottom line: From the Northern Hemisphere, look for the beautiful star Capella and its constellation Auriga the Charioteer.

Flashing stars in autumn? Here are 3 candidates

Messier objects are fuzzy patches in the night sky

Polaris is the present-day North Star of Earth

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