Leo the Lion and its easy to see backward question mark

You’ll see Leo the Lion in the sky in 2 parts. First, the stars making up a backward question mark represent Leo’s head. That part is known as the Sickle. Second, the triangle at the back represents the Lion’s hindquarters. Also, the bright star Regulus is the period at the bottom of the backward question mark. Chart via EarthSky.

Leo the Lion is one of the easiest of the 13 constellations of the zodiac to see. You can start by finding the bright star Regulus. And then trace out a distinctive pattern of stars shaped like a backward question mark, known as the Sickle.

From a Northern Hemisphere perspective, the Lion is a fair-weather friend, springing into the early evening sky around the March equinox.

In fact, April and May are superb months for identifying Leo the Lion. That’s because this constellation becomes visible as soon as darkness falls and stays out until the wee hours of the morning. Remember, you are looking for a backward question mark pattern. Note that Leo’s brightest star, Regulus, is a sparkling blue-white beauty of a star, located at the bottom of the backward question mark. So, Regulus depicts the Lion’s Heart.

The 2025 EarthSky lunar calendar makes a great gift. Get yours today!

The constellation Leo the Lion

Even though the Sickle is the most obvious pattern in Leo, there’s another distinctive shape in Leo. That’s the triangle of stars in eastern Leo representing the Lion’s hindquarters and tail. The name of the brightest star of that triangle is Denebola, which stems from an Arabic term meaning the Lion’s Tail.

Like all stars, Leo’s stars return to the same place in the sky some four minutes earlier daily or two hours earlier monthly. In early April, the constellation Leo reaches its high point for the night around 10 p.m. your local time (11 p.m. local daylight saving time), and starts to sink below the western horizon around 4 a.m. local time (5 a.m. local daylight saving time).

By around May 1, Leo reaches its high point for the night around 8 p.m. local time (9 p.m. local daylight saving time). Also, in early May, the mighty Lion begins to set in the west around 2 a.m. local time (3 a.m. daylight saving time). By June, you’ll find Leo descending in the west in the evening.

Though Leo drifts progressively westward in the early evening sky as the months go by, you can see the Lion in the evening till July. But by late July or early August, the Lion begins to fade into the sunset. And then, from about August 10 to September 16, the sun passes in front of Leo. The constellation returns to the eastern predawn sky in late September or October.

Find Leo by star-hopping from the Big Dipper

If you’re familiar with the Big Dipper star pattern – or asterism – you can star-hop to Leo the Lion every time. After the March equinox, the Big Dipper stands pretty much on its handle in the northeastern sky at nightfall. So at nightfall in April, look for the Big Dipper high in the northeast sky.

And at nightfall in May, look for the almost upside-down Big Dipper high in the north, above Polaris, the North Star. Then, identify the two pointer stars of the Big Dipper. Those are the two outer stars in the Big Dipper’s bowl. Now, draw an imaginary line southward toward the stars in Leo.

An imaginary line drawn southward from the pointer stars in the Big Dipper – the two outer stars in the Dipper’s bowl – points toward Leo the Lion. Chart via EarthSky.

What can you see with a telescope in the Lion?

Check out the chart below to get a sense of the telescopic riches that lie within the boundaries of this constellation.

The star Algieba or γ Leonis is a double star, visible in a small telescope when the atmosphere is steady. If the stars are twinkling wildly, that indicates a turbulent – not steady – atmosphere. On the other hand, if the stars are twinkling very little or not at all, try your luck at splitting Algieba – which looks like a single star to the eye – into its two colorful component stars with the telescope. By the way, you may notice one star appears orangish and the other one appears greenish-yellow.

Also, a close-knit pair of galaxies in Leo provide an inviting target for most telescopes. They are M65 and M66. What’s more, with a low-powered telescope, you might be able to fit both M65 and M66 into a single field of view.

Next, try your luck with a galaxy trio. First, look for M95 and M96. Finally, look for NGC 3628. These three galaxies are known as the Leo Triplet galaxy group.

A map of the constellation Leo the lion. Image via IAU and Sky & Telescope/ Wikimedia Commons (CC BY 3.0).

The constellation in history and myth

Notably, Leo the Lion is associated with the sun and has been for epochs. The ancient Egyptians held Leo in the highest esteem. That’s because the sun shone in front of Leo at the time of the annual flooding of the Nile River, the lifeblood of this agricultural nation.

So maybe the various lion-headed fountains designed by Greek and Roman architects symbolize the life-giving waters being released by the sun’s presence in Leo.

Also, in astrology, the sun rules Leo, one of the three fire signs of the zodiac.

In fact, many stories feature Leo the Lion. Perhaps the two better-known tales feature Heracles’ (also known as Hercules) first labor with the notorious Nemean Lion, and the Roman author Ovid’s rendering of the tragic love affair of Pyramus and Thisbe.

Leo the Lion, with the constellation Leo Minor, as it appears in Urania’s Mirror, a set of cards by Sidney Hall depicting the constellations that was published in 1825. Image via U.S. Library of Congress/ Wikimedia Commons (public domain).

Leo the Lion, from an ancient manuscript dating sometime between 1001 and 1100 CE. Image via National Library of Wales/ Wikimedia Commons (CC0 1.0).

Bottom line: Leo the Lion – one of the zodiacal constellations – is a prominent fixture in the evening sky from April through June. It’s quite easy to spot.

The constellations of the zodiac

Meet Taurus the Bull in the evening sky
Meet Gemini the Twins, home to 2 bright stars
Cancer the Crab and its Beehive Cluster
Leo the Lion and its backward question mark
Virgo the Maiden in northern spring skies
Meet Libra the Scales, a zodiacal constellation
Scorpius the Scorpion is a summertime delight
Sagittarius the Archer and its famous Teapot
Capricornus the Sea-goat has an arrowhead shape
Meet Aquarius the Water Bearer and its stars
Meet Pisces the Fish, 1st constellation of the zodiac
Say hello to Aries the Ram
Born under the sign of Ophiuchus?

The post Leo the Lion and its easy to see backward question mark first appeared on EarthSky.

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You’ll see Leo the Lion in the sky in 2 parts. First, the stars making up a backward question mark represent Leo’s head. That part is known as the Sickle. Second, the triangle at the back represents the Lion’s hindquarters. Also, the bright star Regulus is the period at the bottom of the backward question mark. Chart via EarthSky.

Leo the Lion is one of the easiest of the 13 constellations of the zodiac to see. You can start by finding the bright star Regulus. And then trace out a distinctive pattern of stars shaped like a backward question mark, known as the Sickle.

From a Northern Hemisphere perspective, the Lion is a fair-weather friend, springing into the early evening sky around the March equinox.

In fact, April and May are superb months for identifying Leo the Lion. That’s because this constellation becomes visible as soon as darkness falls and stays out until the wee hours of the morning. Remember, you are looking for a backward question mark pattern. Note that Leo’s brightest star, Regulus, is a sparkling blue-white beauty of a star, located at the bottom of the backward question mark. So, Regulus depicts the Lion’s Heart.

The 2025 EarthSky lunar calendar makes a great gift. Get yours today!

The constellation Leo the Lion

Even though the Sickle is the most obvious pattern in Leo, there’s another distinctive shape in Leo. That’s the triangle of stars in eastern Leo representing the Lion’s hindquarters and tail. The name of the brightest star of that triangle is Denebola, which stems from an Arabic term meaning the Lion’s Tail.

Like all stars, Leo’s stars return to the same place in the sky some four minutes earlier daily or two hours earlier monthly. In early April, the constellation Leo reaches its high point for the night around 10 p.m. your local time (11 p.m. local daylight saving time), and starts to sink below the western horizon around 4 a.m. local time (5 a.m. local daylight saving time).

By around May 1, Leo reaches its high point for the night around 8 p.m. local time (9 p.m. local daylight saving time). Also, in early May, the mighty Lion begins to set in the west around 2 a.m. local time (3 a.m. daylight saving time). By June, you’ll find Leo descending in the west in the evening.

Though Leo drifts progressively westward in the early evening sky as the months go by, you can see the Lion in the evening till July. But by late July or early August, the Lion begins to fade into the sunset. And then, from about August 10 to September 16, the sun passes in front of Leo. The constellation returns to the eastern predawn sky in late September or October.

Find Leo by star-hopping from the Big Dipper

If you’re familiar with the Big Dipper star pattern – or asterism – you can star-hop to Leo the Lion every time. After the March equinox, the Big Dipper stands pretty much on its handle in the northeastern sky at nightfall. So at nightfall in April, look for the Big Dipper high in the northeast sky.

And at nightfall in May, look for the almost upside-down Big Dipper high in the north, above Polaris, the North Star. Then, identify the two pointer stars of the Big Dipper. Those are the two outer stars in the Big Dipper’s bowl. Now, draw an imaginary line southward toward the stars in Leo.

An imaginary line drawn southward from the pointer stars in the Big Dipper – the two outer stars in the Dipper’s bowl – points toward Leo the Lion. Chart via EarthSky.

What can you see with a telescope in the Lion?

Check out the chart below to get a sense of the telescopic riches that lie within the boundaries of this constellation.

The star Algieba or γ Leonis is a double star, visible in a small telescope when the atmosphere is steady. If the stars are twinkling wildly, that indicates a turbulent – not steady – atmosphere. On the other hand, if the stars are twinkling very little or not at all, try your luck at splitting Algieba – which looks like a single star to the eye – into its two colorful component stars with the telescope. By the way, you may notice one star appears orangish and the other one appears greenish-yellow.

Also, a close-knit pair of galaxies in Leo provide an inviting target for most telescopes. They are M65 and M66. What’s more, with a low-powered telescope, you might be able to fit both M65 and M66 into a single field of view.

Next, try your luck with a galaxy trio. First, look for M95 and M96. Finally, look for NGC 3628. These three galaxies are known as the Leo Triplet galaxy group.

A map of the constellation Leo the lion. Image via IAU and Sky & Telescope/ Wikimedia Commons (CC BY 3.0).

The constellation in history and myth

Notably, Leo the Lion is associated with the sun and has been for epochs. The ancient Egyptians held Leo in the highest esteem. That’s because the sun shone in front of Leo at the time of the annual flooding of the Nile River, the lifeblood of this agricultural nation.

So maybe the various lion-headed fountains designed by Greek and Roman architects symbolize the life-giving waters being released by the sun’s presence in Leo.

Also, in astrology, the sun rules Leo, one of the three fire signs of the zodiac.

In fact, many stories feature Leo the Lion. Perhaps the two better-known tales feature Heracles’ (also known as Hercules) first labor with the notorious Nemean Lion, and the Roman author Ovid’s rendering of the tragic love affair of Pyramus and Thisbe.

Leo the Lion, with the constellation Leo Minor, as it appears in Urania’s Mirror, a set of cards by Sidney Hall depicting the constellations that was published in 1825. Image via U.S. Library of Congress/ Wikimedia Commons (public domain).

Leo the Lion, from an ancient manuscript dating sometime between 1001 and 1100 CE. Image via National Library of Wales/ Wikimedia Commons (CC0 1.0).

Bottom line: Leo the Lion – one of the zodiacal constellations – is a prominent fixture in the evening sky from April through June. It’s quite easy to spot.

The constellations of the zodiac

Meet Taurus the Bull in the evening sky
Meet Gemini the Twins, home to 2 bright stars
Cancer the Crab and its Beehive Cluster
Leo the Lion and its backward question mark
Virgo the Maiden in northern spring skies
Meet Libra the Scales, a zodiacal constellation
Scorpius the Scorpion is a summertime delight
Sagittarius the Archer and its famous Teapot
Capricornus the Sea-goat has an arrowhead shape
Meet Aquarius the Water Bearer and its stars
Meet Pisces the Fish, 1st constellation of the zodiac
Say hello to Aries the Ram
Born under the sign of Ophiuchus?

The post Leo the Lion and its easy to see backward question mark first appeared on EarthSky.

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The odds of asteroid 2024 YR4 hitting the moon went up

NASA’s James Webb Space Telescope captured asteroid 2024 YR4 in spring 2025. The inset at top is from NIRCam, which sees reflected light in the near-infrared. The inset at bottom is from MIRI, which sees thermal light in the mid-infrared region. Image via NASA/ ESA/ CSA/ STScI/ A. Rivkin (JHU APL).

The odds of asteroid 2024 YR4 hitting the moon went up

Back in February, we all breathed a sigh of relief after learning the odds of asteroid 2024 YR4 hitting Earth in 2032 and beyond dropped to near zero. But NASA shared an update on April 2, 2025, on the asteroid’s odds of hitting the moon … and they’ve gone up. Back on February 23, 2025, the odds of 2024 YR4 hitting the moon were about 1.8%, or a 1-in-56 chance. Now NASA said they’ve more than doubled. Using new data from the Webb space telescope and ground-based telescopes, NASA said the odds of 2024 YR4 hitting the moon stand at 3.8%.

So when and where might the asteroid hit on the moon? If it hit, it would be on December 22, 2032. There’s a good chance it would be near the moon’s limb, or edge. Which means it could be behind the limb, and therefore we wouldn’t get much of a show. Or it could be on the side facing Earth.

The new observations also give us a better idea of the asteroid’s size. NASA said 2024 YR4 is somewhere between 174 to 220 feet (53 to 67 meters) in size, or about the size of a 10-story building. Previous estimates of the asteroid were around 150 feet (45 meters). So it’s larger than we thought, and if it hits the moon, it’ll pack a good wallop. What a sight that would be!

NASA shared this graphic on April 2, 2025, of the possible locations (yellow dots) of asteroid 2024 YR4 and the moon on December 22, 2032. Image via NASA JPL/CNEOS.

When the odds of 2024 YR4 hitting Earth plummeted

Inventor of the Torino scale, Richard Binzel, told EarthSky on February 23, 2025:

Asteroid 2024 YR4 has now been reassigned to Torino Scale Level 0: the level for No Hazard. Additional tracking of its orbital path reduces its possibility of intersecting the Earth to below the 1-in-1,000 threshold. That is the established level for downgrading to Level 0. [Editor’s note: Odds of 1-in-1,000 are the threshold for Level 0 for any space object smaller than 100 meters. The initial estimates of 2024 YR4 were for a size of 50 meters].

2024 YR4 fell to Torino Scale Level 1 (Green ‘Normal’) on February 20, down from Level 3 (Yellow ‘Meriting Attention by Astronomers’).

Level 0 is labeled as the (White) No Hazard zone on the Torino Scale, which considers the two dimensions of impact probability and impact consequence in assigning its Levels. Find the Torino Scale categories full descriptions here.

In detail for the current probability, the NASA JPL Center for Near-Earth Object Studies now lists the 2024 YR4 probability as 0.00005 (0.005%) or 1-in-20,000 for its passage by Earth in 2032.

That’s zero, folks!

In late January, EarthSky’s Deborah Byrd interviewed asteroid expert Richard Binzel of MIT of MIT – inventor of the Torino Impact Hazard Scale – about a possible strike to Earth by asteroid 2024 YR4. He also talked a lot about the overall picture of how astronomers are keeping Earth safe from asteroid collisions. It’s fascinating stuff. Watch the video here.

Odds of impact increased before dropping

Not long after 2024 YR4’s discovery – in late 2024 – astronomers were saying there was a 1-in-83 chance of a strike. Then the odds went to 1 in 53, then 1 in 43, then 1 in 38, and – at worst – the odds were 1 in 32. That became the new record for an asteroid on the Torino scale, beating the infamous asteroid Apophis in 2004. As we have been saying all along:

It’s likely that the odds will go down to zero with further data.

The new estimates for 2024 YR4 – showing it is no longer considered a possible threat to Earth – come from NASA’s Center for Near Earth Object Studies (CNEOS) at the Jet Propulsion Laboratory in Pasadena, California.

Asteroid 2024 YR4 is moving away from us

Asteroid 2024 YR4 is 116 million miles (188 million km) away and getting farther every second. Some observers noticed the asteroid will be somewhat “close” to the Lucy spacecraft, so its team checked to see if 2024 YR4 would be observable by the spacecraft. But – at its closest to Lucy – the asteroid will still be too faint for the spacecraft’s L’LORRI instrument to detect.

Asteroid 2024 YR4 discovered on Christmas Day 2024

Asteroid 2024 YR4 swept into the view of the ATLAS asteroid impact early warning system – with telescopes in Hawaii, Chile and South Africa – on December 25, 2024.

EarthSky spoke with the inventor of the Torino scale, Richard Binzel of the Massachusetts Institute of Technology (MIT), on January 27, 2025. He said:

In all likelihood, this object will fall to Torino Scale 1 and then 0; or directly fall to 0 with more measurements.

An asteroid’s ranking on the Torino scale

The only asteroid ever to have a higher score on the Torino scale was 99942 Apophis. It briefly had a rating of 4 on the Torino Scale in late 2004. And, yes, Apophis caused a stir and earned the nickname of the Doomsday Asteroid. But asteroid Apophis is now just a zero on the Torino scale. That’s because astronomers watched it carefully, refining their knowledge of its orbit. They determined that Apophis has a negligible risk of impact for at least a century.

So it’s normal for an asteroid’s score on the Torino scale can change. In fact, is likely to change as astronomers gather more observations of the object and also track its motion around the sun.

Watch a video of size comparisons in asteroids, here.

What is the Torino scale?

The IAU has been using the Torino Impact Hazard Scale since 1999 to categorize asteroids that could potentially hit Earth. An object – such as 2024 YR4 – with a score of 3 puts it in the yellow zone. This means the object merits attention by astronomers and the public. The description of a score of 3 reads:

A close encounter, meriting attention by astronomers. Current calculations give a 1% or greater chance of collision capable of localized destruction. Most likely, new telescopic observations will lead to reassignment to Level 0. Attention by public and by public officials is merited if the encounter is less than a decade away.

In fact, most new asteroids that get listed on the Torino scale have their likelihood of hitting Earth go up with more observations … until it drops to zero. That’s because the uncertain path of the asteroid is wide and more observations shrinks the path, making it look more likely, until the path shrinks enough to show that it will not cross Earth’s. It’s likely that’s what will happen with asteroid 2024 YR4 also.

In 2023, EarthSky spoke with the inventor of the Torino scale, Richard Binzel of the Massachusetts Institute of Technology. He said that we should expect more objects to make the Torino scale as our technology improves, allowing us to see smaller objects we otherwise would have missed.

Asteroid Potential Impact Warning Notification

Because the asteroid passed a slim threshold of hitting Earth, it triggered a Potential Impact Warning Notification on January 29, 2025. That warning came from the International Asteroid Warning Network, a global collaboration of observatories, scientific institutions, and other interested parties, coordinated by NASA.

On January 29, the impact probability was a mere 1.3% as calculated by CNEOS and ESA’s Near Earth Objects Coordination Centre in Frascati, Italy, in cooperation with the NEO Dynamic Site (NEODyS-2), also in Italy.

The notice gave the potential date of impact as December 22, 2032, and listed the possible impact locations (from across the eastern Pacific, northern South America, into Africa and southern Asia). If it were to strike Earth, it would cause “severe blast damage.” Specifically, the blast damage could occur as far as 30 miles (50 km) from the site of impact.

DART

If, someday, we find an asteroid that is on a collision course with Earth, we’ll be somewhat prepared. We’ve already sent a mission to hit and move an asteroid as a test of our planetary defense system. That mission was the Double Asteroid Redirection Test (DART), which impacted with an asteroid’s moon named Dimorphos in 2022.

And Dimorphos was much larger than asteroid 2024 YR4, at 525 feet (160 meters) across.

Artist’s illustration of an asteroid approaching Earth. The ATLAS telescope discovered the asteroid 2024 YR24 on December 25, 2024, that – as of January 27, 2025 – had 1-in-83 odds of hitting Earth in 2032. The odds have since changed. Image via urikyo33/ Pixabay.

Bottom line: New observations of asteroid 2024 YR4 with Webb and ground-based telescopes have increased its odds of hitting the moon and show that the asteroid is larger than we first estimated.

Via:

IAU Minor Planet Center

ESA

IAWN

The post The odds of asteroid 2024 YR4 hitting the moon went up first appeared on EarthSky.

from EarthSky https://ift.tt/ndxT8Oc

NASA’s James Webb Space Telescope captured asteroid 2024 YR4 in spring 2025. The inset at top is from NIRCam, which sees reflected light in the near-infrared. The inset at bottom is from MIRI, which sees thermal light in the mid-infrared region. Image via NASA/ ESA/ CSA/ STScI/ A. Rivkin (JHU APL).

The odds of asteroid 2024 YR4 hitting the moon went up

Back in February, we all breathed a sigh of relief after learning the odds of asteroid 2024 YR4 hitting Earth in 2032 and beyond dropped to near zero. But NASA shared an update on April 2, 2025, on the asteroid’s odds of hitting the moon … and they’ve gone up. Back on February 23, 2025, the odds of 2024 YR4 hitting the moon were about 1.8%, or a 1-in-56 chance. Now NASA said they’ve more than doubled. Using new data from the Webb space telescope and ground-based telescopes, NASA said the odds of 2024 YR4 hitting the moon stand at 3.8%.

So when and where might the asteroid hit on the moon? If it hit, it would be on December 22, 2032. There’s a good chance it would be near the moon’s limb, or edge. Which means it could be behind the limb, and therefore we wouldn’t get much of a show. Or it could be on the side facing Earth.

The new observations also give us a better idea of the asteroid’s size. NASA said 2024 YR4 is somewhere between 174 to 220 feet (53 to 67 meters) in size, or about the size of a 10-story building. Previous estimates of the asteroid were around 150 feet (45 meters). So it’s larger than we thought, and if it hits the moon, it’ll pack a good wallop. What a sight that would be!

NASA shared this graphic on April 2, 2025, of the possible locations (yellow dots) of asteroid 2024 YR4 and the moon on December 22, 2032. Image via NASA JPL/CNEOS.

When the odds of 2024 YR4 hitting Earth plummeted

Inventor of the Torino scale, Richard Binzel, told EarthSky on February 23, 2025:

Asteroid 2024 YR4 has now been reassigned to Torino Scale Level 0: the level for No Hazard. Additional tracking of its orbital path reduces its possibility of intersecting the Earth to below the 1-in-1,000 threshold. That is the established level for downgrading to Level 0. [Editor’s note: Odds of 1-in-1,000 are the threshold for Level 0 for any space object smaller than 100 meters. The initial estimates of 2024 YR4 were for a size of 50 meters].

2024 YR4 fell to Torino Scale Level 1 (Green ‘Normal’) on February 20, down from Level 3 (Yellow ‘Meriting Attention by Astronomers’).

Level 0 is labeled as the (White) No Hazard zone on the Torino Scale, which considers the two dimensions of impact probability and impact consequence in assigning its Levels. Find the Torino Scale categories full descriptions here.

In detail for the current probability, the NASA JPL Center for Near-Earth Object Studies now lists the 2024 YR4 probability as 0.00005 (0.005%) or 1-in-20,000 for its passage by Earth in 2032.

That’s zero, folks!

In late January, EarthSky’s Deborah Byrd interviewed asteroid expert Richard Binzel of MIT of MIT – inventor of the Torino Impact Hazard Scale – about a possible strike to Earth by asteroid 2024 YR4. He also talked a lot about the overall picture of how astronomers are keeping Earth safe from asteroid collisions. It’s fascinating stuff. Watch the video here.

Odds of impact increased before dropping

Not long after 2024 YR4’s discovery – in late 2024 – astronomers were saying there was a 1-in-83 chance of a strike. Then the odds went to 1 in 53, then 1 in 43, then 1 in 38, and – at worst – the odds were 1 in 32. That became the new record for an asteroid on the Torino scale, beating the infamous asteroid Apophis in 2004. As we have been saying all along:

It’s likely that the odds will go down to zero with further data.

The new estimates for 2024 YR4 – showing it is no longer considered a possible threat to Earth – come from NASA’s Center for Near Earth Object Studies (CNEOS) at the Jet Propulsion Laboratory in Pasadena, California.

Asteroid 2024 YR4 is moving away from us

Asteroid 2024 YR4 is 116 million miles (188 million km) away and getting farther every second. Some observers noticed the asteroid will be somewhat “close” to the Lucy spacecraft, so its team checked to see if 2024 YR4 would be observable by the spacecraft. But – at its closest to Lucy – the asteroid will still be too faint for the spacecraft’s L’LORRI instrument to detect.

Asteroid 2024 YR4 discovered on Christmas Day 2024

Asteroid 2024 YR4 swept into the view of the ATLAS asteroid impact early warning system – with telescopes in Hawaii, Chile and South Africa – on December 25, 2024.

EarthSky spoke with the inventor of the Torino scale, Richard Binzel of the Massachusetts Institute of Technology (MIT), on January 27, 2025. He said:

In all likelihood, this object will fall to Torino Scale 1 and then 0; or directly fall to 0 with more measurements.

An asteroid’s ranking on the Torino scale

The only asteroid ever to have a higher score on the Torino scale was 99942 Apophis. It briefly had a rating of 4 on the Torino Scale in late 2004. And, yes, Apophis caused a stir and earned the nickname of the Doomsday Asteroid. But asteroid Apophis is now just a zero on the Torino scale. That’s because astronomers watched it carefully, refining their knowledge of its orbit. They determined that Apophis has a negligible risk of impact for at least a century.

So it’s normal for an asteroid’s score on the Torino scale can change. In fact, is likely to change as astronomers gather more observations of the object and also track its motion around the sun.

Watch a video of size comparisons in asteroids, here.

What is the Torino scale?

The IAU has been using the Torino Impact Hazard Scale since 1999 to categorize asteroids that could potentially hit Earth. An object – such as 2024 YR4 – with a score of 3 puts it in the yellow zone. This means the object merits attention by astronomers and the public. The description of a score of 3 reads:

A close encounter, meriting attention by astronomers. Current calculations give a 1% or greater chance of collision capable of localized destruction. Most likely, new telescopic observations will lead to reassignment to Level 0. Attention by public and by public officials is merited if the encounter is less than a decade away.

In fact, most new asteroids that get listed on the Torino scale have their likelihood of hitting Earth go up with more observations … until it drops to zero. That’s because the uncertain path of the asteroid is wide and more observations shrinks the path, making it look more likely, until the path shrinks enough to show that it will not cross Earth’s. It’s likely that’s what will happen with asteroid 2024 YR4 also.

In 2023, EarthSky spoke with the inventor of the Torino scale, Richard Binzel of the Massachusetts Institute of Technology. He said that we should expect more objects to make the Torino scale as our technology improves, allowing us to see smaller objects we otherwise would have missed.

Asteroid Potential Impact Warning Notification

Because the asteroid passed a slim threshold of hitting Earth, it triggered a Potential Impact Warning Notification on January 29, 2025. That warning came from the International Asteroid Warning Network, a global collaboration of observatories, scientific institutions, and other interested parties, coordinated by NASA.

On January 29, the impact probability was a mere 1.3% as calculated by CNEOS and ESA’s Near Earth Objects Coordination Centre in Frascati, Italy, in cooperation with the NEO Dynamic Site (NEODyS-2), also in Italy.

The notice gave the potential date of impact as December 22, 2032, and listed the possible impact locations (from across the eastern Pacific, northern South America, into Africa and southern Asia). If it were to strike Earth, it would cause “severe blast damage.” Specifically, the blast damage could occur as far as 30 miles (50 km) from the site of impact.

DART

If, someday, we find an asteroid that is on a collision course with Earth, we’ll be somewhat prepared. We’ve already sent a mission to hit and move an asteroid as a test of our planetary defense system. That mission was the Double Asteroid Redirection Test (DART), which impacted with an asteroid’s moon named Dimorphos in 2022.

And Dimorphos was much larger than asteroid 2024 YR4, at 525 feet (160 meters) across.

Artist’s illustration of an asteroid approaching Earth. The ATLAS telescope discovered the asteroid 2024 YR24 on December 25, 2024, that – as of January 27, 2025 – had 1-in-83 odds of hitting Earth in 2032. The odds have since changed. Image via urikyo33/ Pixabay.

Bottom line: New observations of asteroid 2024 YR4 with Webb and ground-based telescopes have increased its odds of hitting the moon and show that the asteroid is larger than we first estimated.

Via:

IAU Minor Planet Center

ESA

IAWN

The post The odds of asteroid 2024 YR4 hitting the moon went up first appeared on EarthSky.

from EarthSky https://ift.tt/ndxT8Oc

Above-average hurricane forecast for the Atlantic in 2025

Hurricane Beryl nearing Category 5 intensity in early July 2024. Get the 2025 hurricane forecast for the Atlantic basin below. Image via Atlantic Oceanographic and Meteorological Laboratory/ NOAA.

Hurricane forecast for the Atlantic in 2025

Colorado State University has been predicting tropical activity for the Atlantic hurricane season for 42 years. On Thursday, April 3, 2025, they released their 42nd pre-season hurricane forecast, and it calls for above average-average activity in the tropical Atlantic for the 2025 hurricane season. CSU is forecasting:

17 named storms
9 hurricanes
4 major hurricanes

This is above the 30-year-average (1991-2020) of:
14 named storms
7 hurricanes
3 major hurricanes

The 2024 Atlantic hurricane season saw 18 named storms, 11 hurricanes and five major hurricanes (Category 3 or higher).

Reasoning behind the hurricane forecast

Researchers at Colorado State University base their forecast on 40 years of past data as well as what they call analogs. Analogs are a forecast solution that predicts future weather patterns by identifying past weather situations that closely resemble current conditions. In addition to these analogs, CSU also used up to 40 years of model data from four different meteorological agencies from all over the world. The researchers say all these data are pointing toward a more-active-than-normal hurricane season. There are a few specific areas that CSU focused on for their forecast: ENSO phases and water temperature.

El Niño Southern Oscillation

El Niño Southern Oscillation, also called ENSO, is a global climate pattern that influences weather around the world, including tropical weather. The current ENSO phase is the cool phase, La Niña, during which the waters in the tropical Pacific Ocean are cooler than average.

La Niña can influence tropical development in the Atlantic, however. La Niña doesn’t allow for the development of strong wind shear (a change in wind direction and/or speed with height) over the Atlantic. Wind shear tears apart or weakens hurricanes, so less wind shear during La Niña won’t as easily hinder the development of tropical storms and hurricanes.

The typical influence on tropical weather when La Niña is in place. Image via NOAA.

But La Niña should not continue into the summer. Forecasters predict a switch to ENSO neutral (not fully La Niña or El Niño) during the month of April. And they predict a 62% chance of neutral conditions lasting through August. They do not expect a complete switch to El Niño.

To put it simply, you can think of El Niño as the opposite of La Niña, as it is the warm phase of ENSO. El Niño would create more wind shear over the tropical Atlantic and make it more difficult for tropical systems to develop. But remember: the forecast is for a switch to a neutral phase, not fully El Niño. Due to uncertainty as to what ENSO phase will truly persist through hurricane season, including the possibility of a lingering La Niña, CSU researchers believe this will still have an impact on tropical cyclone development.

Water temperatures

Tropical cyclones, by definition, form over and get their fuel from warm ocean water of at least 80 degrees Fahrenheit (27 Celsius). Water temperatures over the tropical Atlantic are already warmer than average, with the exception of in the far eastern Atlantic where water temperatures are slightly cooler than average. Where water temperatures are currently cooler than average, strong trades have mixed more of the water, making it cooler.

However, within the coming weeks, those trades winds are expected to be weaker, allowing the area with cooler water to gradually warm up and keep the rest of the waters across the Atlantic warmer than average.

Warmer-than-average water temperatures paired with La Niña or even neutral conditions have the potential to create an environment where tropical systems could develop without much inhibition.

Retired names and 2025 Atlantic Basin names

The 2024 Atlantic hurricane season was an active one as well. It had 18 named storms, 11 hurricanes and five major hurricanes. Three of the storms caused so much devastation that their names will never be used again. The names Beryl, Helene and Milton are retired for the Atlantic Basin and will be replaced by Brianna, Holly and Miguel. (Tropical cyclone names are reused every six years, so the next time the 2024 list of names will come up again will be 2030).

The names for the 2025 season are:

Andrea          Barry            Chantal
Dexter           Erin               Fernand
Gabrielle      Humberto   Imelda
Jerry              Karen           Lorenzo
Melissa         Nestor           Olga
Pablo            Rebekah        Sebastien
Tanya            Van                Wendy

Read more about 2025’s hurricane names here.

Hurricane preparedness

Hurricane season in the Atlantic basin begins June 1 and runs through November 30 every year. But the time to be prepared for impacts from a tropical cyclone is before hurricane season begins. You should know your risks from a tropical storm or hurricane: is your biggest threat water or wind? Are you in an evacuation zone, and where should you go when called to evacuate? You should also prepare a hurricane kit full of medicine, fresh water, non-perishable food (and a can opener!) for every person and every pet in your household, plus a radio, chargers and cash. Find more hurricane preparedness tips at NOAA.

A list of tasks to prepare for hurricane season. Via National Weather Service/ NOAA.

Bottom Line: Researchers with Colorado State University are calling for another more-active-than-normal hurricane season with 17 total named storms, nine hurricanes and four major hurricanes.

Read the in-depth report

Stay up to date with all tropical forecasts at NOAA’s National Hurricane Center

Via NOAA

The post Above-average hurricane forecast for the Atlantic in 2025 first appeared on EarthSky.

from EarthSky https://ift.tt/1TjFDOW

Hurricane Beryl nearing Category 5 intensity in early July 2024. Get the 2025 hurricane forecast for the Atlantic basin below. Image via Atlantic Oceanographic and Meteorological Laboratory/ NOAA.

Hurricane forecast for the Atlantic in 2025

Colorado State University has been predicting tropical activity for the Atlantic hurricane season for 42 years. On Thursday, April 3, 2025, they released their 42nd pre-season hurricane forecast, and it calls for above average-average activity in the tropical Atlantic for the 2025 hurricane season. CSU is forecasting:

17 named storms
9 hurricanes
4 major hurricanes

This is above the 30-year-average (1991-2020) of:
14 named storms
7 hurricanes
3 major hurricanes

The 2024 Atlantic hurricane season saw 18 named storms, 11 hurricanes and five major hurricanes (Category 3 or higher).

Reasoning behind the hurricane forecast

Researchers at Colorado State University base their forecast on 40 years of past data as well as what they call analogs. Analogs are a forecast solution that predicts future weather patterns by identifying past weather situations that closely resemble current conditions. In addition to these analogs, CSU also used up to 40 years of model data from four different meteorological agencies from all over the world. The researchers say all these data are pointing toward a more-active-than-normal hurricane season. There are a few specific areas that CSU focused on for their forecast: ENSO phases and water temperature.

El Niño Southern Oscillation

El Niño Southern Oscillation, also called ENSO, is a global climate pattern that influences weather around the world, including tropical weather. The current ENSO phase is the cool phase, La Niña, during which the waters in the tropical Pacific Ocean are cooler than average.

La Niña can influence tropical development in the Atlantic, however. La Niña doesn’t allow for the development of strong wind shear (a change in wind direction and/or speed with height) over the Atlantic. Wind shear tears apart or weakens hurricanes, so less wind shear during La Niña won’t as easily hinder the development of tropical storms and hurricanes.

The typical influence on tropical weather when La Niña is in place. Image via NOAA.

But La Niña should not continue into the summer. Forecasters predict a switch to ENSO neutral (not fully La Niña or El Niño) during the month of April. And they predict a 62% chance of neutral conditions lasting through August. They do not expect a complete switch to El Niño.

To put it simply, you can think of El Niño as the opposite of La Niña, as it is the warm phase of ENSO. El Niño would create more wind shear over the tropical Atlantic and make it more difficult for tropical systems to develop. But remember: the forecast is for a switch to a neutral phase, not fully El Niño. Due to uncertainty as to what ENSO phase will truly persist through hurricane season, including the possibility of a lingering La Niña, CSU researchers believe this will still have an impact on tropical cyclone development.

Water temperatures

Tropical cyclones, by definition, form over and get their fuel from warm ocean water of at least 80 degrees Fahrenheit (27 Celsius). Water temperatures over the tropical Atlantic are already warmer than average, with the exception of in the far eastern Atlantic where water temperatures are slightly cooler than average. Where water temperatures are currently cooler than average, strong trades have mixed more of the water, making it cooler.

However, within the coming weeks, those trades winds are expected to be weaker, allowing the area with cooler water to gradually warm up and keep the rest of the waters across the Atlantic warmer than average.

Warmer-than-average water temperatures paired with La Niña or even neutral conditions have the potential to create an environment where tropical systems could develop without much inhibition.

Retired names and 2025 Atlantic Basin names

The 2024 Atlantic hurricane season was an active one as well. It had 18 named storms, 11 hurricanes and five major hurricanes. Three of the storms caused so much devastation that their names will never be used again. The names Beryl, Helene and Milton are retired for the Atlantic Basin and will be replaced by Brianna, Holly and Miguel. (Tropical cyclone names are reused every six years, so the next time the 2024 list of names will come up again will be 2030).

The names for the 2025 season are:

Andrea          Barry            Chantal
Dexter           Erin               Fernand
Gabrielle      Humberto   Imelda
Jerry              Karen           Lorenzo
Melissa         Nestor           Olga
Pablo            Rebekah        Sebastien
Tanya            Van                Wendy

Read more about 2025’s hurricane names here.

Hurricane preparedness

Hurricane season in the Atlantic basin begins June 1 and runs through November 30 every year. But the time to be prepared for impacts from a tropical cyclone is before hurricane season begins. You should know your risks from a tropical storm or hurricane: is your biggest threat water or wind? Are you in an evacuation zone, and where should you go when called to evacuate? You should also prepare a hurricane kit full of medicine, fresh water, non-perishable food (and a can opener!) for every person and every pet in your household, plus a radio, chargers and cash. Find more hurricane preparedness tips at NOAA.

A list of tasks to prepare for hurricane season. Via National Weather Service/ NOAA.

Bottom Line: Researchers with Colorado State University are calling for another more-active-than-normal hurricane season with 17 total named storms, nine hurricanes and four major hurricanes.

Read the in-depth report

Stay up to date with all tropical forecasts at NOAA’s National Hurricane Center

Via NOAA

The post Above-average hurricane forecast for the Atlantic in 2025 first appeared on EarthSky.

from EarthSky https://ift.tt/1TjFDOW

See the Atlantic hurricanes name list for 2025

Here’s the list of names for tropical cyclones and hurricanes in 2025 for the Atlantic basin.

Names for Atlantic hurricanes and tropical cyclones

The 2025 Atlantic hurricane season officially starts June 1 and extends through November 30. NOAA’s Climate Prediction Center will release their hurricane season outlook for this year in late May. Meanwhile, Colorado State University (CSU) also puts out a hurricane outlook, which it issued on April 3. But what are the names for the 2025 Atlantic tropical cyclones and hurricanes?

See the complete list of 2025 tropical cyclone and hurricane names above. If any of these storms become truly destructive in 2025, the World Meteorological Organization, which is in charge of the list, retires and replaces the name. For example, in 2024, the World Meteorological Organization retired the names Beryl, Helene and Milton. Helene, in particular, became the deadliest storm in the U.S. since Katrina in 2005.

If you live near the Atlantic basin, you should keep up-to-date with forecasts from the National Hurricane Center.

Learn more about how to prepare for hurricane season.

2025 EarthSky lunar calendar is available. A unique and beautiful poster-sized calendar with phases of the moon for every night of the year. Get yours today!

Where do hurricane names come from?

Meteorologists long ago learned that naming tropical storms and hurricanes helps people remember the storms, communicate about them more effectively, and consequently stay safer if and when a particular storm strikes a coast.

These experts assign names to tropical storms according to an approved list before the start of each hurricane season. The U.S. National Hurricane Center started this practice in the early 1950s. Now, the World Meteorological Organization (WMO) generates and maintains the list of hurricane names.

Here are the hurricane names for 2025

Atlantic hurricane names (season runs from June 1 to November 30) are: Andrea, Barry, Chantal, Dexter, Erin, Fernand, Gabrielle, Humberto, Imelda, Jerry, Karen, Lorenzo, Melissa, Nestor, Olga, Pablo, Rebekah, Sebastien, Tanya, Van and Wendy.

Eastern North Pacific hurricane names (season runs from May 15 to November 30) are: Alvin, Barbara, Cosme, Dalila, Erick, Flossie, Gil, Henriette, Ivo, Juliette, Kiko, Lorena, Mario, Narda, Octave, Priscilla, Raymond, Sonia, Tico, Velma, Wallis, Xina, York and Zelda.

If you’re interested, you can view those names, and names for upcoming years, at the U.S. National Hurricane Center.

In 2022, Hurricane Ian devastated Florida’s Gulf Coast. It also brought flooding to central Florida, ripped roofs off on the Atlantic Coast and then menaced South Carolina. The name Ian will never again be used for a tropical cyclone or hurricane. Image via NOAA/ GOES.

How and why did hurricanes first begin receiving names?

While people have been naming major storms for hundreds of years, most hurricanes originally had a designation using a system of latitude-longitude numbers. This was useful to meteorologists trying to track these storms. Unfortunately, this system confused people living on coasts seeking hurricane information.

In the early 1950s, the U.S. National Hurricane Center first developed a formal practice for storm naming for the Atlantic Ocean. At that time, storms got their names according to a phonetic alphabet (e.g., Able, Baker, Charlie) and the names used were the same for each hurricane season. In other words, the first hurricane of a season was always named “Able,” the second “Baker,” and so on.

In 1953, to avoid the repetitive use of names, the National Weather Service revised the system to give storms female names. By doing this, the National Weather Service was mimicking the habit of naval meteorologists, who named the storms after women, much as ships at sea traditionally had female names.

In 1978–1979, they revised the system again to include both female and male hurricane names.

See the complete history of naming hurricanes, including retired names, from NOAA.

When does a storm receive a name?

Tropical storms get a name when they display a rotating circulation pattern and wind speeds reach 39 miles per hour (63 kilometers per hour). A tropical storm develops into a hurricane when wind speeds go above 74 mph (119 km/h).

Experts have developed lists of hurricane names for many of the major ocean basins around the world. Today, there are six lists of hurricane names in use for Atlantic Ocean and Eastern North Pacific storms. These lists rotate, one each year. So that means the list of this year’s hurricane names for each basin will come up again six years from now.

However, there’s an exception to this practice. The World Meteorological Organization retires the names of extremely damaging hurricanes for legal, cultural sensitivity and historical reasons. For example, they retired the name Katrina in 2005 following the devastating impact that Hurricane Katrina had on New Orleans. In 2022, the World Meteorological Organization Hurricane Committee retired the names Fiona and Ian.

Hurricane Katrina on August 28, 2005. Image via NASA.

Bottom line: Get the list of names for the 2025 season for Atlantic tropical cyclones and hurricanes. Read more about how the naming system came to be.

Read more: What is a hurricane storm surge?

The post See the Atlantic hurricanes name list for 2025 first appeared on EarthSky.

from EarthSky https://ift.tt/XLVrvuc

Here’s the list of names for tropical cyclones and hurricanes in 2025 for the Atlantic basin.

Names for Atlantic hurricanes and tropical cyclones

The 2025 Atlantic hurricane season officially starts June 1 and extends through November 30. NOAA’s Climate Prediction Center will release their hurricane season outlook for this year in late May. Meanwhile, Colorado State University (CSU) also puts out a hurricane outlook, which it issued on April 3. But what are the names for the 2025 Atlantic tropical cyclones and hurricanes?

See the complete list of 2025 tropical cyclone and hurricane names above. If any of these storms become truly destructive in 2025, the World Meteorological Organization, which is in charge of the list, retires and replaces the name. For example, in 2024, the World Meteorological Organization retired the names Beryl, Helene and Milton. Helene, in particular, became the deadliest storm in the U.S. since Katrina in 2005.

If you live near the Atlantic basin, you should keep up-to-date with forecasts from the National Hurricane Center.

Learn more about how to prepare for hurricane season.

2025 EarthSky lunar calendar is available. A unique and beautiful poster-sized calendar with phases of the moon for every night of the year. Get yours today!

Where do hurricane names come from?

Meteorologists long ago learned that naming tropical storms and hurricanes helps people remember the storms, communicate about them more effectively, and consequently stay safer if and when a particular storm strikes a coast.

These experts assign names to tropical storms according to an approved list before the start of each hurricane season. The U.S. National Hurricane Center started this practice in the early 1950s. Now, the World Meteorological Organization (WMO) generates and maintains the list of hurricane names.

Here are the hurricane names for 2025

Atlantic hurricane names (season runs from June 1 to November 30) are: Andrea, Barry, Chantal, Dexter, Erin, Fernand, Gabrielle, Humberto, Imelda, Jerry, Karen, Lorenzo, Melissa, Nestor, Olga, Pablo, Rebekah, Sebastien, Tanya, Van and Wendy.

Eastern North Pacific hurricane names (season runs from May 15 to November 30) are: Alvin, Barbara, Cosme, Dalila, Erick, Flossie, Gil, Henriette, Ivo, Juliette, Kiko, Lorena, Mario, Narda, Octave, Priscilla, Raymond, Sonia, Tico, Velma, Wallis, Xina, York and Zelda.

If you’re interested, you can view those names, and names for upcoming years, at the U.S. National Hurricane Center.

In 2022, Hurricane Ian devastated Florida’s Gulf Coast. It also brought flooding to central Florida, ripped roofs off on the Atlantic Coast and then menaced South Carolina. The name Ian will never again be used for a tropical cyclone or hurricane. Image via NOAA/ GOES.

How and why did hurricanes first begin receiving names?

While people have been naming major storms for hundreds of years, most hurricanes originally had a designation using a system of latitude-longitude numbers. This was useful to meteorologists trying to track these storms. Unfortunately, this system confused people living on coasts seeking hurricane information.

In the early 1950s, the U.S. National Hurricane Center first developed a formal practice for storm naming for the Atlantic Ocean. At that time, storms got their names according to a phonetic alphabet (e.g., Able, Baker, Charlie) and the names used were the same for each hurricane season. In other words, the first hurricane of a season was always named “Able,” the second “Baker,” and so on.

In 1953, to avoid the repetitive use of names, the National Weather Service revised the system to give storms female names. By doing this, the National Weather Service was mimicking the habit of naval meteorologists, who named the storms after women, much as ships at sea traditionally had female names.

In 1978–1979, they revised the system again to include both female and male hurricane names.

See the complete history of naming hurricanes, including retired names, from NOAA.

When does a storm receive a name?

Tropical storms get a name when they display a rotating circulation pattern and wind speeds reach 39 miles per hour (63 kilometers per hour). A tropical storm develops into a hurricane when wind speeds go above 74 mph (119 km/h).

Experts have developed lists of hurricane names for many of the major ocean basins around the world. Today, there are six lists of hurricane names in use for Atlantic Ocean and Eastern North Pacific storms. These lists rotate, one each year. So that means the list of this year’s hurricane names for each basin will come up again six years from now.

However, there’s an exception to this practice. The World Meteorological Organization retires the names of extremely damaging hurricanes for legal, cultural sensitivity and historical reasons. For example, they retired the name Katrina in 2005 following the devastating impact that Hurricane Katrina had on New Orleans. In 2022, the World Meteorological Organization Hurricane Committee retired the names Fiona and Ian.

Hurricane Katrina on August 28, 2005. Image via NASA.

Bottom line: Get the list of names for the 2025 season for Atlantic tropical cyclones and hurricanes. Read more about how the naming system came to be.

Read more: What is a hurricane storm surge?

The post See the Atlantic hurricanes name list for 2025 first appeared on EarthSky.

from EarthSky https://ift.tt/XLVrvuc

Surprising galaxy shines through fog of the early universe

This image shows the incredibly distant galaxy JADES GS-z13-1 (the red dot at center). This surprising galaxy emits light that has shifted into infrared wavelengths during its long journey across the cosmos. Image via NASA/ ESA/ CSA/ Brant Robertson (UC Santa Cruz)/ Ben Johnson (CfA)/ Sandro Tacchella (Cambridge)/ Phill Cargile (CfA)/ Joris Witstok (Cambridge, University of Copenhagen)/ P. Jakobsen (University of Copenhagen)/ Alyssa Pagan (STScI)/ Mahdi Zamani (ESA/Webb)/ JADES Collaboration.

• The early universe was filled with a thick fog of neutral hydrogen. Even though the first stars and galaxies emitted copious amounts of ultraviolet light, that light struggled to pierce the fog.
• It took hundreds of millions of years for the neutral hydrogen to become ionized – electrons stripped from protons – allowing light to travel freely through space.
• But one galaxy with a bright, unexpected hydrogen emission caught astronomers by surprise. We see the galaxy JADES-GS-z13-1 just 330 million years after the Big Bang. It has a strong hydrogen emission line even though the cosmic fog should have absorbed it.

NASA published this original story on March 26, 2025. Edits by EarthSky.

Surprising galaxy in the early universe

Using NASA’s James Webb Space Telescope, researchers can examine ancient galaxies to probe secrets of the early universe. On March 26, 2025, an international team of astronomers said they’ve identified bright hydrogen emission from a galaxy in an unexpectedly early time in the universe’s history. The surprise finding challenges researchers to explain how this light could have pierced the thick fog of neutral hydrogen that filled space at that time.

Joris Witstok of the University of Cambridge in the United Kingdom and the Cosmic Dawn Center at the University of Copenhagen in Denmark led the international team. The researchers published their peer-reviewed study in the journal Nature on March 26, 2025.

The discovery of the surprising galaxy

The Webb telescope’s Near-Infrared Camera (NIRCam) discovered the incredibly distant galaxy JADES-GS-z13-1. We observe it as it existed just 330 million years after the Big Bang. Researchers used the galaxy’s brightness in different infrared filters to estimate its redshift. A redshift measures a galaxy’s distance from Earth based on how its light has stretched out during its journey through expanding space.

The NIRCam imaging yielded an initial redshift estimate of 12.9. Seeking to confirm its extreme redshift, the researchers then observed the galaxy using Webb’s Near-Infrared Spectrograph (NIRSpec) instrument.

In the resulting spectrum, the scientists confirmed the redshift as 13.0. So this equates to seeing the galaxy just 330 million years after the Big Bang. That would be just a small fraction of the universe’s present age of 13.8 billion years old. But an unexpected feature stood out as well: one specific, distinctly bright wavelength of light, known as Lyman-alpha emission, radiated by hydrogen atoms. This emission was far stronger than astronomers thought possible at this early stage in the universe’s development.

We see galaxy JADES-GS-z13-1 as it was just 330 million years after the Big Bang. An international team of astronomers identified a powerful hydrogen emission from this galaxy at an unexpectedly early period in the universe’s history. Image via NASA/ ESA/ CSA/ Brant Robertson (UC Santa Cruz)/ Ben Johnson (CfA)/ Sandro Tacchella (Cambridge)/ Phill Cargile (CfA)/ Joris Witstok (Cambridge, University of Copenhagen)/ P. Jakobsen (University of Copenhagen)/ Alyssa Pagan (STScI)/ Mahdi Zamani (ESA/Webb)/ JADES Collaboration.

Seeing through the fog

Roberto Maiolino, a team member from the University of Cambridge and University College London, explained:

The early universe was bathed in a thick fog of neutral hydrogen. Most of this haze was lifted in a process called reionization, which was completed about 1 billion years after the big bang. We see GS-z13-1 when the universe was only 330 million years old. Yet it shows a surprisingly clear, telltale signature of Lyman-alpha emission that can only be seen once the surrounding fog has fully lifted. This result was totally unexpected by theories of early galaxy formation and has caught astronomers by surprise.

Before and during the era of reionization, there were immense amounts of neutral hydrogen fog. It surrounded galaxies, blocking any energetic ultraviolet light they emitted. Picture it similar to the filtering effect of colored glass. Until enough stars formed and could ionize the hydrogen gas, no such light – including Lyman-alpha emission – could escape from these fledgling galaxies to reach Earth. The confirmation of Lyman-alpha radiation from this galaxy, therefore, has great implications for our understanding of the early universe.

Kevin Hainline, a team member from the University of Arizona, said:

We really shouldn’t have found a galaxy like this, given our understanding of the way the universe has evolved. We could think of the early universe as shrouded with a thick fog that would make it exceedingly difficult to find even powerful lighthouses peeking through. Yet here we see the beam of light from this galaxy piercing the veil. This fascinating emission line has huge ramifications for how and when the universe reionized.

Looking for answers

Scientists don’t yet know the source of the Lyman-alpha radiation from this galaxy. But it may include the first light from the earliest generation of stars to form in the universe. Witstok said:

The large bubble of ionized hydrogen surrounding this galaxy might have been created by a peculiar population of stars … much more massive, hotter and more luminous than stars formed at later epochs, and possibly representative of the first generation of stars.

A powerful active galactic nucleus, driven by one of the first supermassive black holes, is another possibility the team identified.

The galaxy JADES-GS-z13-1 has a redshift of z=13.05. That means we see it just 330 million years after the Big Bang. This graph shows its bright emission from hydrogen known as Lyman-alpha emission. This is surprising, because a dense fog of neutral hydrogen in the early universe should have absorbed it. Image via NASA/ ESA/ CSA/ S. Carniani (Scuola Normale Superiore)/ P. Jakobsen (University of Copenhagen)/ Joseph Olmsted (STScI).

Bottom line: Astronomers have discovered a surprising galaxy showing a bright hydrogen emission shining through the fog of the early universe.

Source: Witnessing the onset of reionization through Lyman-a emission at redshift 13

Via NASA

The 2025 EarthSky lunar calendar makes a great gift. Get yours today!

The post Surprising galaxy shines through fog of the early universe first appeared on EarthSky.

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This image shows the incredibly distant galaxy JADES GS-z13-1 (the red dot at center). This surprising galaxy emits light that has shifted into infrared wavelengths during its long journey across the cosmos. Image via NASA/ ESA/ CSA/ Brant Robertson (UC Santa Cruz)/ Ben Johnson (CfA)/ Sandro Tacchella (Cambridge)/ Phill Cargile (CfA)/ Joris Witstok (Cambridge, University of Copenhagen)/ P. Jakobsen (University of Copenhagen)/ Alyssa Pagan (STScI)/ Mahdi Zamani (ESA/Webb)/ JADES Collaboration.

• The early universe was filled with a thick fog of neutral hydrogen. Even though the first stars and galaxies emitted copious amounts of ultraviolet light, that light struggled to pierce the fog.
• It took hundreds of millions of years for the neutral hydrogen to become ionized – electrons stripped from protons – allowing light to travel freely through space.
• But one galaxy with a bright, unexpected hydrogen emission caught astronomers by surprise. We see the galaxy JADES-GS-z13-1 just 330 million years after the Big Bang. It has a strong hydrogen emission line even though the cosmic fog should have absorbed it.

NASA published this original story on March 26, 2025. Edits by EarthSky.

Surprising galaxy in the early universe

Using NASA’s James Webb Space Telescope, researchers can examine ancient galaxies to probe secrets of the early universe. On March 26, 2025, an international team of astronomers said they’ve identified bright hydrogen emission from a galaxy in an unexpectedly early time in the universe’s history. The surprise finding challenges researchers to explain how this light could have pierced the thick fog of neutral hydrogen that filled space at that time.

Joris Witstok of the University of Cambridge in the United Kingdom and the Cosmic Dawn Center at the University of Copenhagen in Denmark led the international team. The researchers published their peer-reviewed study in the journal Nature on March 26, 2025.

The discovery of the surprising galaxy

The Webb telescope’s Near-Infrared Camera (NIRCam) discovered the incredibly distant galaxy JADES-GS-z13-1. We observe it as it existed just 330 million years after the Big Bang. Researchers used the galaxy’s brightness in different infrared filters to estimate its redshift. A redshift measures a galaxy’s distance from Earth based on how its light has stretched out during its journey through expanding space.

The NIRCam imaging yielded an initial redshift estimate of 12.9. Seeking to confirm its extreme redshift, the researchers then observed the galaxy using Webb’s Near-Infrared Spectrograph (NIRSpec) instrument.

In the resulting spectrum, the scientists confirmed the redshift as 13.0. So this equates to seeing the galaxy just 330 million years after the Big Bang. That would be just a small fraction of the universe’s present age of 13.8 billion years old. But an unexpected feature stood out as well: one specific, distinctly bright wavelength of light, known as Lyman-alpha emission, radiated by hydrogen atoms. This emission was far stronger than astronomers thought possible at this early stage in the universe’s development.

We see galaxy JADES-GS-z13-1 as it was just 330 million years after the Big Bang. An international team of astronomers identified a powerful hydrogen emission from this galaxy at an unexpectedly early period in the universe’s history. Image via NASA/ ESA/ CSA/ Brant Robertson (UC Santa Cruz)/ Ben Johnson (CfA)/ Sandro Tacchella (Cambridge)/ Phill Cargile (CfA)/ Joris Witstok (Cambridge, University of Copenhagen)/ P. Jakobsen (University of Copenhagen)/ Alyssa Pagan (STScI)/ Mahdi Zamani (ESA/Webb)/ JADES Collaboration.

Seeing through the fog

Roberto Maiolino, a team member from the University of Cambridge and University College London, explained:

The early universe was bathed in a thick fog of neutral hydrogen. Most of this haze was lifted in a process called reionization, which was completed about 1 billion years after the big bang. We see GS-z13-1 when the universe was only 330 million years old. Yet it shows a surprisingly clear, telltale signature of Lyman-alpha emission that can only be seen once the surrounding fog has fully lifted. This result was totally unexpected by theories of early galaxy formation and has caught astronomers by surprise.

Before and during the era of reionization, there were immense amounts of neutral hydrogen fog. It surrounded galaxies, blocking any energetic ultraviolet light they emitted. Picture it similar to the filtering effect of colored glass. Until enough stars formed and could ionize the hydrogen gas, no such light – including Lyman-alpha emission – could escape from these fledgling galaxies to reach Earth. The confirmation of Lyman-alpha radiation from this galaxy, therefore, has great implications for our understanding of the early universe.

Kevin Hainline, a team member from the University of Arizona, said:

We really shouldn’t have found a galaxy like this, given our understanding of the way the universe has evolved. We could think of the early universe as shrouded with a thick fog that would make it exceedingly difficult to find even powerful lighthouses peeking through. Yet here we see the beam of light from this galaxy piercing the veil. This fascinating emission line has huge ramifications for how and when the universe reionized.

Looking for answers

Scientists don’t yet know the source of the Lyman-alpha radiation from this galaxy. But it may include the first light from the earliest generation of stars to form in the universe. Witstok said:

The large bubble of ionized hydrogen surrounding this galaxy might have been created by a peculiar population of stars … much more massive, hotter and more luminous than stars formed at later epochs, and possibly representative of the first generation of stars.

A powerful active galactic nucleus, driven by one of the first supermassive black holes, is another possibility the team identified.

The galaxy JADES-GS-z13-1 has a redshift of z=13.05. That means we see it just 330 million years after the Big Bang. This graph shows its bright emission from hydrogen known as Lyman-alpha emission. This is surprising, because a dense fog of neutral hydrogen in the early universe should have absorbed it. Image via NASA/ ESA/ CSA/ S. Carniani (Scuola Normale Superiore)/ P. Jakobsen (University of Copenhagen)/ Joseph Olmsted (STScI).

Bottom line: Astronomers have discovered a surprising galaxy showing a bright hydrogen emission shining through the fog of the early universe.

Source: Witnessing the onset of reionization through Lyman-a emission at redshift 13

Via NASA

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Coma Berenices: See how Leo the Lion lost his tail

To spot Coma Berenices, look behind Leo the Lion. Coma Berenices also contains a famous grouping of stars, the Coma star cluster.

The constellation of Coma Berenices

Coma Berenices is a constellation readily visible in spring skies that represents the hair of Queen Berenice. The constellation itself may not be very bright – you’ll need a dark sky to see most of its stars – but its location is easy enough to find. It trails Leo the Lion, with the Big Dipper high above it and Virgo with bright Spica below.

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View larger. | The constellation Coma Berenices via IAU/ Sky & Telescope/ Wikipedia (CC BY 3.0).

Finding Coma Berenices

How can you find it? One way is to use the famous constellation Leo the Lion, shown on our chart at the top of this post. It’s now in the east each evening and Leo is relatively easy to see. The front part of the Lion looks like a backward question mark, and the back part is a little triangle, which includes the star Denebola, marked on the chart above. The word Deneb in a star name always means tail, and this star marks the tail of Leo.

Do you know how to use the pointer stars in the Big Dipper to locate Polaris, the North Star? Instead of going northward from the pointer stars to Polaris, go southward to find the constellation Leo.

Now imagine that Leo is holding its tail out. In the place where you might see a “puff” at the end of the Lion’s tail, you’ll notice a fuzzy patch not too far away from Denebola. This is the constellation Coma Berenices, or Berenice’s Hair. In fact, the constellation Coma Berenices was once part of the constellation Leo.

The stars of Berenice’s Hair

The three main stars in Coma Berenices are Alpha, Beta, and Gamma Comae Berenices. They form the upper left portion of a square. The brightest of these stars is Beta Comae Berenices, at magnitude 4.2. It lies at the corner of the partial square.

Near the star Gamma Comae Berenices, at the top of the half-box, is a famous star cluster. Under dark skies, you can find Melotte 111, although it is more familiarly known as the Coma star cluster.

A tangle of stars

To see Melotte 111, the Coma star cluster, you need a dark sky. It is an open star cluster, a loose collection of stars held together by gravity.

Under a dark sky, the Coma star cluster can look like a glint on the sky. If you can’t spot this wispy and glimmering group of stars with the unaided eye, try binoculars. The cluster is actually fairly large, covering 5 degrees of the sky.

See the chart below.

The circle on this map shows you the location of the Coma star cluster in the constellation Coma Berenices. You’ll need dark skies to locate Coma Berenices – and the Coma star cluster – but you can use Leo to help you locate it. Chart via Stellarium.org. Used with permission.

Viewing Tip: To enhance your view of the Coma star cluster, take a paper towel tube or roll up some dark paper into a tube and place it to your eye. The tube will shield your eye from the glare of any ground lights. Binoculars or opera glasses will also lead to a better viewing experience.

The Coma star cluster is estimated to be about 288 light-years away and has at least 37 known stars that are 400 million years old. It is the third-closest open cluster to our Earth and sun. Only the Ursa Major cluster (the bowl stars of the Big Dipper) and the Hyades cluster (the head of Taurus the Bull) are closer.

The Coma galaxy cluster

There is another Coma cluster in the constellation of Coma Berenices, but that one is a cluster of galaxies. The names of the two are easily confused.

There’s also a vast cluster of galaxies located in the direction of the constellation Coma Berenices. Here is a majestic face-on spiral galaxy located deep within it. Read more about the Coma galaxy cluster. Image via NASA.

Formerly part of Leo the Lion

On old star charts like the one below, the tail of the constellation Leo the Lion has a curve. There’s a star there, Beta Leonis or Denebola, whose name means tail. Yet – on the dome of the sky – the Lion’s Tail used to extend out straight behind Leo, and the constellation of the Lion encompassed a much-larger area of the sky. The Greek-Egyptian astronomer Ptolemy and others considered a modern-day constellation – which we call Coma Berenices – as the tuft at the end of Leo’s tail. It was only a few hundred years ago that Coma Berenices became a separate constellation.

Leo the Lion, with the constellation Leo Minor, as it appears in Urania’s Mirror, a set of cards by Sidney Hall depicting the constellations published in 1825. Image via U.S. Library of Congress/ Wikimedia Commons (public domain).

Mythology of Coma Berenices

The official constellation is relatively new, but the lore behind the constellation is old. The story goes that an ancient Egyptian queen, Berenice, feared for her husband’s life as he went into battle. She prayed to Aphrodite, promising to cut off her long, luxurious curls if the king returned safely. He did, and Berenice kept her promise and cut off her hair, placing it as a sacrifice on Aphrodite’s altar.

But the next day the hair was gone!

The enraged king was angry that the temple priests had not protected the precious locks. A quick-thinking astronomer saved the day, or rather night, by pointing to the cascading stars at the end of Leo’s tail. He told the king that these were the queen’s tresses placed in the sky by Aphrodite for all to see.

This appeased the king and queen, and saved the priests from a beheading.

Thus, Leo lost his tail … and, ultimately, we gained a constellation.

The constellations of Coma Berenices (Berenice’s Hair), Boötes the Herdsman, and Canes Venatici the Hunting Dogs. Image via Wikipedia (public domain).

Bottom line: Coma Berenices is the constellation of Queen Berenice’s Hair. It used to be the tail of Leo the Lion before it became its own constellation. It contains a large open star cluster easily viewed in binoculars.

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To spot Coma Berenices, look behind Leo the Lion. Coma Berenices also contains a famous grouping of stars, the Coma star cluster.

The constellation of Coma Berenices

Coma Berenices is a constellation readily visible in spring skies that represents the hair of Queen Berenice. The constellation itself may not be very bright – you’ll need a dark sky to see most of its stars – but its location is easy enough to find. It trails Leo the Lion, with the Big Dipper high above it and Virgo with bright Spica below.

2025 EarthSky lunar calendar is available. A unique and beautiful poster-sized calendar with phases of the moon for every night of the year. Get yours today!

View larger. | The constellation Coma Berenices via IAU/ Sky & Telescope/ Wikipedia (CC BY 3.0).

Finding Coma Berenices

How can you find it? One way is to use the famous constellation Leo the Lion, shown on our chart at the top of this post. It’s now in the east each evening and Leo is relatively easy to see. The front part of the Lion looks like a backward question mark, and the back part is a little triangle, which includes the star Denebola, marked on the chart above. The word Deneb in a star name always means tail, and this star marks the tail of Leo.

Do you know how to use the pointer stars in the Big Dipper to locate Polaris, the North Star? Instead of going northward from the pointer stars to Polaris, go southward to find the constellation Leo.

Now imagine that Leo is holding its tail out. In the place where you might see a “puff” at the end of the Lion’s tail, you’ll notice a fuzzy patch not too far away from Denebola. This is the constellation Coma Berenices, or Berenice’s Hair. In fact, the constellation Coma Berenices was once part of the constellation Leo.

The stars of Berenice’s Hair

The three main stars in Coma Berenices are Alpha, Beta, and Gamma Comae Berenices. They form the upper left portion of a square. The brightest of these stars is Beta Comae Berenices, at magnitude 4.2. It lies at the corner of the partial square.

Near the star Gamma Comae Berenices, at the top of the half-box, is a famous star cluster. Under dark skies, you can find Melotte 111, although it is more familiarly known as the Coma star cluster.

A tangle of stars

To see Melotte 111, the Coma star cluster, you need a dark sky. It is an open star cluster, a loose collection of stars held together by gravity.

Under a dark sky, the Coma star cluster can look like a glint on the sky. If you can’t spot this wispy and glimmering group of stars with the unaided eye, try binoculars. The cluster is actually fairly large, covering 5 degrees of the sky.

See the chart below.

The circle on this map shows you the location of the Coma star cluster in the constellation Coma Berenices. You’ll need dark skies to locate Coma Berenices – and the Coma star cluster – but you can use Leo to help you locate it. Chart via Stellarium.org. Used with permission.

Viewing Tip: To enhance your view of the Coma star cluster, take a paper towel tube or roll up some dark paper into a tube and place it to your eye. The tube will shield your eye from the glare of any ground lights. Binoculars or opera glasses will also lead to a better viewing experience.

The Coma star cluster is estimated to be about 288 light-years away and has at least 37 known stars that are 400 million years old. It is the third-closest open cluster to our Earth and sun. Only the Ursa Major cluster (the bowl stars of the Big Dipper) and the Hyades cluster (the head of Taurus the Bull) are closer.

The Coma galaxy cluster

There is another Coma cluster in the constellation of Coma Berenices, but that one is a cluster of galaxies. The names of the two are easily confused.

There’s also a vast cluster of galaxies located in the direction of the constellation Coma Berenices. Here is a majestic face-on spiral galaxy located deep within it. Read more about the Coma galaxy cluster. Image via NASA.

Formerly part of Leo the Lion

On old star charts like the one below, the tail of the constellation Leo the Lion has a curve. There’s a star there, Beta Leonis or Denebola, whose name means tail. Yet – on the dome of the sky – the Lion’s Tail used to extend out straight behind Leo, and the constellation of the Lion encompassed a much-larger area of the sky. The Greek-Egyptian astronomer Ptolemy and others considered a modern-day constellation – which we call Coma Berenices – as the tuft at the end of Leo’s tail. It was only a few hundred years ago that Coma Berenices became a separate constellation.

Leo the Lion, with the constellation Leo Minor, as it appears in Urania’s Mirror, a set of cards by Sidney Hall depicting the constellations published in 1825. Image via U.S. Library of Congress/ Wikimedia Commons (public domain).

Mythology of Coma Berenices

The official constellation is relatively new, but the lore behind the constellation is old. The story goes that an ancient Egyptian queen, Berenice, feared for her husband’s life as he went into battle. She prayed to Aphrodite, promising to cut off her long, luxurious curls if the king returned safely. He did, and Berenice kept her promise and cut off her hair, placing it as a sacrifice on Aphrodite’s altar.

But the next day the hair was gone!

The enraged king was angry that the temple priests had not protected the precious locks. A quick-thinking astronomer saved the day, or rather night, by pointing to the cascading stars at the end of Leo’s tail. He told the king that these were the queen’s tresses placed in the sky by Aphrodite for all to see.

This appeased the king and queen, and saved the priests from a beheading.

Thus, Leo lost his tail … and, ultimately, we gained a constellation.

The constellations of Coma Berenices (Berenice’s Hair), Boötes the Herdsman, and Canes Venatici the Hunting Dogs. Image via Wikipedia (public domain).

Bottom line: Coma Berenices is the constellation of Queen Berenice’s Hair. It used to be the tail of Leo the Lion before it became its own constellation. It contains a large open star cluster easily viewed in binoculars.

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The post Coma Berenices: See how Leo the Lion lost his tail first appeared on EarthSky.

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Here’s how to see the Lunar X and V at 1st-quarter moon

View at EarthSky Community Photos. | Kannan A in Singapore wrote on April 19, 2021: “Upon a close look at the moon tonight, I realized that the Lunar X and Lunar V were clearly visible. These are transient lunar features visible on the lunar surface for about 4 hours once a month. They are most striking when they are visible on the shadow side of the terminator. But they will remain visible against the lunar surface even after the terminator has moved because they are brighter than the surrounding area.” Thank you, Kannan!

2025 EarthSky lunar calendar is available now. A unique and beautiful poster-sized calendar with phases of the moon for every night of the year. Get yours today!

Lunar X and Lunar V

Have you heard of Lunar X and Lunar V? They are famous optical features on the moon, visible through telescopes. So, when the moon’s terminator – or line between light and dark on the moon – is located in just the right place, you can see a letter X and a letter V on the moon’s surface. Are they a sign of an alien visitation? No. Rather, Lunar X is a great example of how lighting and topography can combine on a planet or moon to produce a pattern that seems familiar to the human eye.

In reality, the illusion of Lunar X is created by sunlight falling on the rims/ridges between the craters La Caille, Bianchini and Purbach. The V is caused by light illuminating crater Ukert, along with several smaller craters.

View at EarthSky Community Photos. | Radu Anghel captured this image from Bacau, Romania, on April 27, 2023. Radu wrote: “X and V from tonight’s moon.” Thank you, Radu! Learn how to see Lunar X and V below.

When are they visible?

Basically, people see Lunar X and Lunar V at each cycle of the moon, but only for a short time. In fact, they’re observable for about four hours around the 1st quarter moon phase.

View at EarthSky Community Photos. | Matthew Chin from Hong Kong, China, shared this image of the moon, where Lunar X and Lunar V are visible, on January 18, 2024. Thank you, Matthew!

Bottom line: Lunar X and Lunar V are optical features on the moon. They are visible through a telescope for several hours around the time of the 1st quarter moon.

The post Here’s how to see the Lunar X and V at 1st-quarter moon first appeared on EarthSky.

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View at EarthSky Community Photos. | Kannan A in Singapore wrote on April 19, 2021: “Upon a close look at the moon tonight, I realized that the Lunar X and Lunar V were clearly visible. These are transient lunar features visible on the lunar surface for about 4 hours once a month. They are most striking when they are visible on the shadow side of the terminator. But they will remain visible against the lunar surface even after the terminator has moved because they are brighter than the surrounding area.” Thank you, Kannan!

2025 EarthSky lunar calendar is available now. A unique and beautiful poster-sized calendar with phases of the moon for every night of the year. Get yours today!

Lunar X and Lunar V

Have you heard of Lunar X and Lunar V? They are famous optical features on the moon, visible through telescopes. So, when the moon’s terminator – or line between light and dark on the moon – is located in just the right place, you can see a letter X and a letter V on the moon’s surface. Are they a sign of an alien visitation? No. Rather, Lunar X is a great example of how lighting and topography can combine on a planet or moon to produce a pattern that seems familiar to the human eye.

In reality, the illusion of Lunar X is created by sunlight falling on the rims/ridges between the craters La Caille, Bianchini and Purbach. The V is caused by light illuminating crater Ukert, along with several smaller craters.

View at EarthSky Community Photos. | Radu Anghel captured this image from Bacau, Romania, on April 27, 2023. Radu wrote: “X and V from tonight’s moon.” Thank you, Radu! Learn how to see Lunar X and V below.

When are they visible?

Basically, people see Lunar X and Lunar V at each cycle of the moon, but only for a short time. In fact, they’re observable for about four hours around the 1st quarter moon phase.

View at EarthSky Community Photos. | Matthew Chin from Hong Kong, China, shared this image of the moon, where Lunar X and Lunar V are visible, on January 18, 2024. Thank you, Matthew!

Bottom line: Lunar X and Lunar V are optical features on the moon. They are visible through a telescope for several hours around the time of the 1st quarter moon.

The post Here’s how to see the Lunar X and V at 1st-quarter moon first appeared on EarthSky.

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