Meet the Crab Nebula, remnant of an exploding star

This image of the Crab Nebula is a composite of 5 images taken using 5 telescopes, spanning wavelengths from radio to X-ray. Colors represent wavelengths as follows: VLA (radio) in red; Spitzer Space Telescope (infrared) in yellow; Hubble Space Telescope (visible) in green; XMM-Newton (ultraviolet) in blue; and Chandra X-ray Observatory (X-ray) in purple. Image via JPL.

A supernova explodes

The Crab Nebula is a supernova remnant. It’s what’s left of an exploded star. A vast expanding cloud of gas and dust, it surrounds one of the densest objects in the universe, a neutron star.

Chinese astronomers noticed the sudden appearance of a star blazing in the daytime sky on July 4, 1054 CE. It likely outshone the brightest planet, Venus, and was temporarily the 3rd-brightest object in the sky, after the sun and moon. This “guest star” – the exploding supernova – remained visible in daylight for some 23 days. At night it shone near Tianguan – a star we now call Zeta Tauri, in the constellation Taurus the Bull – for nearly two years. Then it faded from view.

The supernova erupted – and the Crab Nebula formed – about 6,500 light-years away.

The 2025 lunar calendars are here! Best New Year’s gifts in the universe! Check ’em out here.

Since the Crab Nebula is located among some of the brightest stars and constellations in the heavens, it is easy to find. And it’s best placed for evening observing from late fall through early spring. You can spot the Crab Nebula near the star Zeta Tauri, which is the end star of one of the horns of Taurus the Bull.

The Crab Nebula and supernova in history

The ancestral Puebloan people in the American Southwest may have viewed the bright new star in 1054. A crescent moon was in the sky near the new star on the morning of July 5, the day following the observations by the Chinese. So the pictograph below, from Chaco Canyon in New Mexico, might depict the event. The multi-spiked star to the left represents the supernova near the crescent moon. Furthermore, the handprint above may signify the importance of the event or may be the artist’s signature.

After exploding onto the scene in 1054 and shining brightly for two years, there are no reports of anything unusual in this spot in the sky until 1731. Then in that year, English amateur astronomer John Bevis recorded an observation of a faint nebulosity. In 1758, French comet-hunter Charles Messier spotted the hazy patch. It became the first entry in his catalog of objects that were fuzzy but not comets, now known as the Messier Catalog. Thus, the Crab Nebula has the name M1.

In 1844, astronomer William Parsons – the 3rd Earl of Rosse – observed M1 through his large telescope in Ireland. Because he described it as having a shape resembling a crab, that became its familiar nickname.

Yet it wasn’t until 1921 that people made the association between the Crab Nebula and Chinese records of the 1054 guest star.

Ancestral Puebloan pictograph possibly depicting the Crab Nebula supernova in 1054 CE in Chaco Canyon, New Mexico. Image via Alex Marentes/ Wikimedia Commons (CC BY-SA 2.0).

How to see the Crab Nebula

Since this beautiful nebula shines at magnitude 8.4, it requires magnification to see. Fortunately, it’s relatively easy to find with binoculars or a telescope due to its location near several bright stars. Plus, it’s near several recognizable constellations. Although you can see it at some time of night all year except – from roughly May through July when it’s too close to the sun – the best observing is late the Northern Hemisphere fall through early spring.

To find the Crab Nebula, first draw an imaginary line from bright Betelgeuse in Orion to Capella in Auriga. About halfway along that line is the star Beta Tauri (or Elnath) on the Taurus-Auriga border.

Having identified Beta Tauri, backtrack a little more than a 3rd of the way back to Betelgeuse to find the fainter star Zeta Tauri. Scanning the area around Zeta Tauri should reveal a tiny, faint smudge. It’s about a degree (twice the width of the full moon) from Zeta Tauri and more or less in the direction of Beta Tauri.

View larger. | As shown here, you see the location of the Crab Nebula (in the square crosshairs) relative to Capella, Betelgeuse, Beta Tauri and Zeta Tauri. Image via Stellarium. Used with permission.

Views through binoculars or a telescope

Binoculars and small telescopes are useful for finding the object and showing its roughly oblong shape. However, they won’t show the filamentary structure or any of its internal detail. Here are two examples showing what to expect in binoculars or through a telescope.

Simulated view of Zeta Tauri and the Crab Nebula in a 7-degree field of view. Chart via Stellarium. Used with permission.

First, the eyepiece view, above, simulates a 7-degree field of view centered around Zeta Tauri. This is what you might expect from a 7 X 50 pair of binoculars. Of course, the exact orientation and visibility will range widely depending on time of observation, sky conditions and so on. Scan around Zeta Tauri for the faint nebulosity.

Simulated view of Zeta Tauri and Crab Nebula with a 3.5-degree field of view. Chart via Stellarium. Used with permission.

Then the second image, above, simulates an approximately 3.5-degree view that you might see through a small telescope or finder scope. To give you a clear idea of scale, two full moons would fit with room to spare in the space between Zeta Tauri and the Crab Nebula in this chart.

Keep in mind that exact conditions will vary.

Science of the Crab Nebula

The Crab Nebula is an oval gaseous nebula with fine filamentary (thread-like) structures, expanding at around 930 miles (1,500 km) per second. In its heart is a neutron star about the mass of the sun but only about 12-19 miles (20-30 km) in diameter. This neutron star is also a pulsar that spins about 30 times per second. The neutron star’s powerful magnetic field concentrates radiation emitted by the star as two beams that appear to flash periodically as the beams sweep into view. It lies about 6,500 light-years from Earth.

The flashing of the Crab Nebula pulsar in infrared wavelengths. However, this view is considerably slower than its 30 times per second period. Image via Cambridge University Lucky Imaging Group/ Wikimedia Commons/ GFDL.

The Hubble Space Telescope imaged the center of the Crab Nebula in 2016. Notably, there’s a rapidly spinning neutron star at the center of the nebula, known as a pulsar. That’s the rightmost of the two stars near the center of the image. The bluish light is radiation emitted by electrons speeding at close to the speed of light along the neutron star’s powerful magnetic field. Scientists think the wispy circular features move out of the pulsar due to a shockwave that piles up highly energetic particles coming from high-speed winds emanating from the neutron star. Image via NASA/ ESA/ J. Hester/ M. Weisskopf.

Views from the Hubble and Webb space telescopes

This side-by-side comparison of the Crab Nebula as seen by the Hubble Space Telescope in optical light (left) and the James Webb Space Telescope in infrared light (right) reveals different details. By studying the collected Webb data, and consulting previous observations of the Crab taken by other telescopes like Hubble, astronomers can build a more comprehensive understanding of this supernova remnant. Hubble Image via NASA/ ESA J. Hester, A. Loll; Webb Image via NASA ESA CSA STScI T. Temim.

The Crab Nebula may be from a new type of supernova

For a long time scientists thought the Crab Nebula was the remnant of a type II supernova. But in June 2021, scientists announced they’d finally found evidence for a new type of supernova, an electron-capture supernova. Consequently, they now believe the Crab Nebula may be this type of supernova. Read more about this exciting discovery.

The center of the Crab Nebula is approximately at RA: 5h 34m 32s; Dec: +22° 0′ 52″

Bottom line: The Crab Nebula is visible with binoculars and small telescopes, and relatively easy to find since it’s near bright stars in prominent constellations. Although astronomers long thought that it was the remnant of a type II supernova, there’s increasing evidence that it may have been a new type of supernova called an electron capture supernova.

The post Meet the Crab Nebula, remnant of an exploding star first appeared on EarthSky.

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This image of the Crab Nebula is a composite of 5 images taken using 5 telescopes, spanning wavelengths from radio to X-ray. Colors represent wavelengths as follows: VLA (radio) in red; Spitzer Space Telescope (infrared) in yellow; Hubble Space Telescope (visible) in green; XMM-Newton (ultraviolet) in blue; and Chandra X-ray Observatory (X-ray) in purple. Image via JPL.

A supernova explodes

The Crab Nebula is a supernova remnant. It’s what’s left of an exploded star. A vast expanding cloud of gas and dust, it surrounds one of the densest objects in the universe, a neutron star.

Chinese astronomers noticed the sudden appearance of a star blazing in the daytime sky on July 4, 1054 CE. It likely outshone the brightest planet, Venus, and was temporarily the 3rd-brightest object in the sky, after the sun and moon. This “guest star” – the exploding supernova – remained visible in daylight for some 23 days. At night it shone near Tianguan – a star we now call Zeta Tauri, in the constellation Taurus the Bull – for nearly two years. Then it faded from view.

The supernova erupted – and the Crab Nebula formed – about 6,500 light-years away.

The 2025 lunar calendars are here! Best New Year’s gifts in the universe! Check ’em out here.

Since the Crab Nebula is located among some of the brightest stars and constellations in the heavens, it is easy to find. And it’s best placed for evening observing from late fall through early spring. You can spot the Crab Nebula near the star Zeta Tauri, which is the end star of one of the horns of Taurus the Bull.

The Crab Nebula and supernova in history

The ancestral Puebloan people in the American Southwest may have viewed the bright new star in 1054. A crescent moon was in the sky near the new star on the morning of July 5, the day following the observations by the Chinese. So the pictograph below, from Chaco Canyon in New Mexico, might depict the event. The multi-spiked star to the left represents the supernova near the crescent moon. Furthermore, the handprint above may signify the importance of the event or may be the artist’s signature.

After exploding onto the scene in 1054 and shining brightly for two years, there are no reports of anything unusual in this spot in the sky until 1731. Then in that year, English amateur astronomer John Bevis recorded an observation of a faint nebulosity. In 1758, French comet-hunter Charles Messier spotted the hazy patch. It became the first entry in his catalog of objects that were fuzzy but not comets, now known as the Messier Catalog. Thus, the Crab Nebula has the name M1.

In 1844, astronomer William Parsons – the 3rd Earl of Rosse – observed M1 through his large telescope in Ireland. Because he described it as having a shape resembling a crab, that became its familiar nickname.

Yet it wasn’t until 1921 that people made the association between the Crab Nebula and Chinese records of the 1054 guest star.

Ancestral Puebloan pictograph possibly depicting the Crab Nebula supernova in 1054 CE in Chaco Canyon, New Mexico. Image via Alex Marentes/ Wikimedia Commons (CC BY-SA 2.0).

How to see the Crab Nebula

Since this beautiful nebula shines at magnitude 8.4, it requires magnification to see. Fortunately, it’s relatively easy to find with binoculars or a telescope due to its location near several bright stars. Plus, it’s near several recognizable constellations. Although you can see it at some time of night all year except – from roughly May through July when it’s too close to the sun – the best observing is late the Northern Hemisphere fall through early spring.

To find the Crab Nebula, first draw an imaginary line from bright Betelgeuse in Orion to Capella in Auriga. About halfway along that line is the star Beta Tauri (or Elnath) on the Taurus-Auriga border.

Having identified Beta Tauri, backtrack a little more than a 3rd of the way back to Betelgeuse to find the fainter star Zeta Tauri. Scanning the area around Zeta Tauri should reveal a tiny, faint smudge. It’s about a degree (twice the width of the full moon) from Zeta Tauri and more or less in the direction of Beta Tauri.

View larger. | As shown here, you see the location of the Crab Nebula (in the square crosshairs) relative to Capella, Betelgeuse, Beta Tauri and Zeta Tauri. Image via Stellarium. Used with permission.

Views through binoculars or a telescope

Binoculars and small telescopes are useful for finding the object and showing its roughly oblong shape. However, they won’t show the filamentary structure or any of its internal detail. Here are two examples showing what to expect in binoculars or through a telescope.

Simulated view of Zeta Tauri and the Crab Nebula in a 7-degree field of view. Chart via Stellarium. Used with permission.

First, the eyepiece view, above, simulates a 7-degree field of view centered around Zeta Tauri. This is what you might expect from a 7 X 50 pair of binoculars. Of course, the exact orientation and visibility will range widely depending on time of observation, sky conditions and so on. Scan around Zeta Tauri for the faint nebulosity.

Simulated view of Zeta Tauri and Crab Nebula with a 3.5-degree field of view. Chart via Stellarium. Used with permission.

Then the second image, above, simulates an approximately 3.5-degree view that you might see through a small telescope or finder scope. To give you a clear idea of scale, two full moons would fit with room to spare in the space between Zeta Tauri and the Crab Nebula in this chart.

Keep in mind that exact conditions will vary.

Science of the Crab Nebula

The Crab Nebula is an oval gaseous nebula with fine filamentary (thread-like) structures, expanding at around 930 miles (1,500 km) per second. In its heart is a neutron star about the mass of the sun but only about 12-19 miles (20-30 km) in diameter. This neutron star is also a pulsar that spins about 30 times per second. The neutron star’s powerful magnetic field concentrates radiation emitted by the star as two beams that appear to flash periodically as the beams sweep into view. It lies about 6,500 light-years from Earth.

The flashing of the Crab Nebula pulsar in infrared wavelengths. However, this view is considerably slower than its 30 times per second period. Image via Cambridge University Lucky Imaging Group/ Wikimedia Commons/ GFDL.

The Hubble Space Telescope imaged the center of the Crab Nebula in 2016. Notably, there’s a rapidly spinning neutron star at the center of the nebula, known as a pulsar. That’s the rightmost of the two stars near the center of the image. The bluish light is radiation emitted by electrons speeding at close to the speed of light along the neutron star’s powerful magnetic field. Scientists think the wispy circular features move out of the pulsar due to a shockwave that piles up highly energetic particles coming from high-speed winds emanating from the neutron star. Image via NASA/ ESA/ J. Hester/ M. Weisskopf.

Views from the Hubble and Webb space telescopes

This side-by-side comparison of the Crab Nebula as seen by the Hubble Space Telescope in optical light (left) and the James Webb Space Telescope in infrared light (right) reveals different details. By studying the collected Webb data, and consulting previous observations of the Crab taken by other telescopes like Hubble, astronomers can build a more comprehensive understanding of this supernova remnant. Hubble Image via NASA/ ESA J. Hester, A. Loll; Webb Image via NASA ESA CSA STScI T. Temim.

The Crab Nebula may be from a new type of supernova

For a long time scientists thought the Crab Nebula was the remnant of a type II supernova. But in June 2021, scientists announced they’d finally found evidence for a new type of supernova, an electron-capture supernova. Consequently, they now believe the Crab Nebula may be this type of supernova. Read more about this exciting discovery.

The center of the Crab Nebula is approximately at RA: 5h 34m 32s; Dec: +22° 0′ 52″

Bottom line: The Crab Nebula is visible with binoculars and small telescopes, and relatively easy to find since it’s near bright stars in prominent constellations. Although astronomers long thought that it was the remnant of a type II supernova, there’s increasing evidence that it may have been a new type of supernova called an electron capture supernova.

The post Meet the Crab Nebula, remnant of an exploding star first appeared on EarthSky.

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A planetary alignment on January 25, 2025?

Will there be a planetary alignment on January 25, 2025? EarthSky’s Deborah Byrd and John Goss have the scoop on planets in January 2025!

A planetary alignment on January 25, 2025?

If you’re on social media, by now you might have seen the breathless announcements of a planetary alignment on January 25, 2025. A flurry of videos and memes is claiming that all eight planets will be in a line on one side of the sun and visible in our nighttime sky. Is it true? Nope. Why January 25? We have no idea. But there will be six planets in our evening sky throughout January. And yes, they’re in a line … like always.

So, no, there won’t be a planetary alignment with everything neatly stacked on one side of the sun. But there will be lots of planets for observing in the nighttime sky! Not just on January 25 but throughout January and February.

Why the planets are always ‘in a line’

The planets in our solar system orbit our sun more or less in a flat plane. The Earth-sun plane – called the ecliptic – more or less defines the plane of the planets and sun. So, in our sky, the planets always appear somewhere along a line. That line across our sky – the path of the sun and moon – is just a 2-dimensional representation of the 3-dimensional plane of our solar system.

So the planets always travel in a line across our sky. And that means that – if there’s more than one planet up there … it always lines up with any other planet (and the moon and sun).

And in January 2025 there are four bright planets – and two faint planets – in the evening sky. Yup. They’re arrayed in a line across the sky.

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!

Of the 6 planets in January’s evening sky, you’ll need charts and binoculars or a telescope to see 2 of them. So that leaves 4 bright planets in a line across our sky. Why a line? Because the planets orbit our sun in a flat plane, so they are always located along a line in our sky. Astronomers call this line the ecliptic (the green line on this chart). It’s the path our sun takes in the sky. Here’s what you’ll likely see in January 2025 from mid-northern latitudes.

Planets on January 25, 2025

So what will the sky look like on January 25, 2025? Below you’ll find two views of the sky with all six planets – the four bright ones and the two exceedingly faint ones – as seen from mid-latitudes in the Northern Hemisphere. Below them, you’ll find more charts, showing what that view looks like from the point of view of someone hovering in space above our solar system.

So you can see that, yes, the planets in the evening sky are arrayed across our sky in a line. Planets in our solar system, when they are visible, are always in a line because they follow the path of the sun – the ecliptic – across our sky. But they aren’t in a line stretching out, one behind another, from the sun, into 3-dimensional space.

And Mercury isn’t even in the evening sky. It’s in the morning sky in January 2025.

Here’s the same scene as above, with Uranus and Neptune added in. These 2 planets won’t be visible without charts and probably optical aid. So that leaves 4 bright planets in a line across our sky in January 2025. Image via EarthSky.

Here’s a more detailed view, showing what the sky will look like on January 25, 2025, about 90 minutes after darkness falls. You’ll be able to see 4 bright planets and 2 dim ones if you use binoculars. The 7th planet, Mercury, is too close to the sun to see. Image via Stellarium and EarthSky.

If you could hover above our solar system and look down on it on January 25, 2025, this is where you’d find the planets. While 6 planets will be arrayed across in our evening sky – 4 visible and 2 not – the planets won’t make a line in 3D space, going outward from the sun. Not even close!
Image via EarthSky.

Can you see 4 planets in the sky at once?

The answer to the question above depends on what you mean by “see.” If you mean see with your eye alone, then, yes! You can see four wonderfully bright planets. Start in the west, where the sun has just set. As the sky darkens, you’ll spot Venus easily, because it shines more brightly than any star. In late January, you’ll find Saturn between Venus and the horizon. Saturn is sinking toward the sunset, which will make it harder to spot in February.

The other two planets that you can see with your eyes alone are Jupiter, which will be bright and higher in the sky than Venus or Saturn when night falls, and Mars, which is reddish and will be rising in the east soon after dark. Mars is nice and bright right now, at its best viewing in two years! And that’s really what makes the January sky full of planets so very, very special.

Binoculars for Uranus, telescope for Neptune

But if you have access to optical aids, you’ll also be able to see Uranus and Neptune in January’s sky. Spotting Uranus and Neptune is hard. Uranus is theoretically visible to the eye alone … but requires a very dark sky to be glimpsed with the eye. Binoculars will show it more easily. As for Neptune, no, it’s not visible to the eye alone under any circumstances. Binoculars might show it, but you’ll likely need a telescope to see it.

But here’s the good news. If you’ve identified the first four planets, you can see they trace a rough line from one horizon to the other. And Uranus and Neptune will also be along that line.

Here’s a tip for finding Uranus. Uranus is the 7th major planet outward from our sun. It’s dim. But you might glimpse it, if you have a dark sky. In the general vicinity of Jupiter, you’ll see a fuzzy, dipper-shaped cluster of stars … it’s called the Pleiades, or Seven Sisters. And Uranus is not too far away from the Pleiades. Binoculars will really help. Not sure where to look? Try using Stellarium – setting your observing time and location – to pinpoint Uranus.

Here’s a tip for finding Neptune. Neptune is the 8th planet outward from the sun. It dimmer even than Uranus. But it’s near some other bright objects now: dazzling Venus and bright, golden Saturn. In fact, on January 29 and 30, Neptune will be just a few moon-widths to the side of Venus.

So where’s the outlier, Mercury? While the misinformation churns about planets in the evening sky in January 2025, Mercury is having a pretty good apparition – close to the sun, as always – in the morning sky. Mercury will move into the evening sky in February. But, at that point, Saturn and Neptune will be departing. They’ll all pass each other in the glare of sunset.

Technically, by the end of February, all seven planets will be in the sky at once. But Neptune will be impossible to see so close to the sun, and Mercury and Saturn will be challenging.

Will we ever see this so-called planetary alignment?

Will we ever see the planets when they’re all lined up together on one side of the sun? Watch the video to find out.

EarthSky’s Will Triggs brings you the good and bad news about the supposed planetary alignment of January 25, 2025.

A great planetary alignment?

So the January 25, 2025, great planetary alignment idea does have a grain of truth. But … the planets aren’t going to be strung out on one side of the sun, one behind another.

The team at EarthSky has been presenting night sky information for nearly 50 years. And we’ve seen the term great planetary alignment tossed around now and again, probably first with the idea of a Jupiter Effect in the 1970s and ’80s. Has it ever been true? No.

But could it be true? Could all eight major planets in our solar system – Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune – make a single line on one side of the sun? When will that happen? The answer, apparently, is never. In Jean Meeus’ book Mathematical Astronomy Morsels, he said our eight planets will line up to within 3.6 degrees of sky every 396 billion years. The sun is currently about 4.6 billion years old and will bloat into a red giant some 5 to 6 billion years from now, swallowing the inner planets in the process.

So, no, we’ll never see the planets form a line on one side of the sun.

But, sometimes, we can appreciate the beauty and wonder of seeing several bright planets arrayed across our sky. And January 2025 is one of those times!

Will there be a planetary alignment on January 25, 2025? Image via Charles Thonney/ Pixabay/ EarthSky.

Bottom line: You’ve heard the internet rumor of a great planetary alignment on January 25, 2025. So what’s true and what isn’t? The answers are here.

The post A planetary alignment on January 25, 2025? first appeared on EarthSky.

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Will there be a planetary alignment on January 25, 2025? EarthSky’s Deborah Byrd and John Goss have the scoop on planets in January 2025!

A planetary alignment on January 25, 2025?

If you’re on social media, by now you might have seen the breathless announcements of a planetary alignment on January 25, 2025. A flurry of videos and memes is claiming that all eight planets will be in a line on one side of the sun and visible in our nighttime sky. Is it true? Nope. Why January 25? We have no idea. But there will be six planets in our evening sky throughout January. And yes, they’re in a line … like always.

So, no, there won’t be a planetary alignment with everything neatly stacked on one side of the sun. But there will be lots of planets for observing in the nighttime sky! Not just on January 25 but throughout January and February.

Why the planets are always ‘in a line’

The planets in our solar system orbit our sun more or less in a flat plane. The Earth-sun plane – called the ecliptic – more or less defines the plane of the planets and sun. So, in our sky, the planets always appear somewhere along a line. That line across our sky – the path of the sun and moon – is just a 2-dimensional representation of the 3-dimensional plane of our solar system.

So the planets always travel in a line across our sky. And that means that – if there’s more than one planet up there … it always lines up with any other planet (and the moon and sun).

And in January 2025 there are four bright planets – and two faint planets – in the evening sky. Yup. They’re arrayed in a line across the sky.

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!

Of the 6 planets in January’s evening sky, you’ll need charts and binoculars or a telescope to see 2 of them. So that leaves 4 bright planets in a line across our sky. Why a line? Because the planets orbit our sun in a flat plane, so they are always located along a line in our sky. Astronomers call this line the ecliptic (the green line on this chart). It’s the path our sun takes in the sky. Here’s what you’ll likely see in January 2025 from mid-northern latitudes.

Planets on January 25, 2025

So what will the sky look like on January 25, 2025? Below you’ll find two views of the sky with all six planets – the four bright ones and the two exceedingly faint ones – as seen from mid-latitudes in the Northern Hemisphere. Below them, you’ll find more charts, showing what that view looks like from the point of view of someone hovering in space above our solar system.

So you can see that, yes, the planets in the evening sky are arrayed across our sky in a line. Planets in our solar system, when they are visible, are always in a line because they follow the path of the sun – the ecliptic – across our sky. But they aren’t in a line stretching out, one behind another, from the sun, into 3-dimensional space.

And Mercury isn’t even in the evening sky. It’s in the morning sky in January 2025.

Here’s the same scene as above, with Uranus and Neptune added in. These 2 planets won’t be visible without charts and probably optical aid. So that leaves 4 bright planets in a line across our sky in January 2025. Image via EarthSky.

Here’s a more detailed view, showing what the sky will look like on January 25, 2025, about 90 minutes after darkness falls. You’ll be able to see 4 bright planets and 2 dim ones if you use binoculars. The 7th planet, Mercury, is too close to the sun to see. Image via Stellarium and EarthSky.

If you could hover above our solar system and look down on it on January 25, 2025, this is where you’d find the planets. While 6 planets will be arrayed across in our evening sky – 4 visible and 2 not – the planets won’t make a line in 3D space, going outward from the sun. Not even close!
Image via EarthSky.

Can you see 4 planets in the sky at once?

The answer to the question above depends on what you mean by “see.” If you mean see with your eye alone, then, yes! You can see four wonderfully bright planets. Start in the west, where the sun has just set. As the sky darkens, you’ll spot Venus easily, because it shines more brightly than any star. In late January, you’ll find Saturn between Venus and the horizon. Saturn is sinking toward the sunset, which will make it harder to spot in February.

The other two planets that you can see with your eyes alone are Jupiter, which will be bright and higher in the sky than Venus or Saturn when night falls, and Mars, which is reddish and will be rising in the east soon after dark. Mars is nice and bright right now, at its best viewing in two years! And that’s really what makes the January sky full of planets so very, very special.

Binoculars for Uranus, telescope for Neptune

But if you have access to optical aids, you’ll also be able to see Uranus and Neptune in January’s sky. Spotting Uranus and Neptune is hard. Uranus is theoretically visible to the eye alone … but requires a very dark sky to be glimpsed with the eye. Binoculars will show it more easily. As for Neptune, no, it’s not visible to the eye alone under any circumstances. Binoculars might show it, but you’ll likely need a telescope to see it.

But here’s the good news. If you’ve identified the first four planets, you can see they trace a rough line from one horizon to the other. And Uranus and Neptune will also be along that line.

Here’s a tip for finding Uranus. Uranus is the 7th major planet outward from our sun. It’s dim. But you might glimpse it, if you have a dark sky. In the general vicinity of Jupiter, you’ll see a fuzzy, dipper-shaped cluster of stars … it’s called the Pleiades, or Seven Sisters. And Uranus is not too far away from the Pleiades. Binoculars will really help. Not sure where to look? Try using Stellarium – setting your observing time and location – to pinpoint Uranus.

Here’s a tip for finding Neptune. Neptune is the 8th planet outward from the sun. It dimmer even than Uranus. But it’s near some other bright objects now: dazzling Venus and bright, golden Saturn. In fact, on January 29 and 30, Neptune will be just a few moon-widths to the side of Venus.

So where’s the outlier, Mercury? While the misinformation churns about planets in the evening sky in January 2025, Mercury is having a pretty good apparition – close to the sun, as always – in the morning sky. Mercury will move into the evening sky in February. But, at that point, Saturn and Neptune will be departing. They’ll all pass each other in the glare of sunset.

Technically, by the end of February, all seven planets will be in the sky at once. But Neptune will be impossible to see so close to the sun, and Mercury and Saturn will be challenging.

Will we ever see this so-called planetary alignment?

Will we ever see the planets when they’re all lined up together on one side of the sun? Watch the video to find out.

EarthSky’s Will Triggs brings you the good and bad news about the supposed planetary alignment of January 25, 2025.

A great planetary alignment?

So the January 25, 2025, great planetary alignment idea does have a grain of truth. But … the planets aren’t going to be strung out on one side of the sun, one behind another.

The team at EarthSky has been presenting night sky information for nearly 50 years. And we’ve seen the term great planetary alignment tossed around now and again, probably first with the idea of a Jupiter Effect in the 1970s and ’80s. Has it ever been true? No.

But could it be true? Could all eight major planets in our solar system – Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune – make a single line on one side of the sun? When will that happen? The answer, apparently, is never. In Jean Meeus’ book Mathematical Astronomy Morsels, he said our eight planets will line up to within 3.6 degrees of sky every 396 billion years. The sun is currently about 4.6 billion years old and will bloat into a red giant some 5 to 6 billion years from now, swallowing the inner planets in the process.

So, no, we’ll never see the planets form a line on one side of the sun.

But, sometimes, we can appreciate the beauty and wonder of seeing several bright planets arrayed across our sky. And January 2025 is one of those times!

Will there be a planetary alignment on January 25, 2025? Image via Charles Thonney/ Pixabay/ EarthSky.

Bottom line: You’ve heard the internet rumor of a great planetary alignment on January 25, 2025. So what’s true and what isn’t? The answers are here.

The post A planetary alignment on January 25, 2025? first appeared on EarthSky.

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Extreme winds on exoplanet reach 20,000 mph

Astronomers found extreme winds on exoplanet WASP-127b reach 20,000 mph (32,000 km/hr). EarthSky’s Will Triggs explains in this short video.

• Extreme winds on exoplanet WASP-127b reach 20,000 mph (32,000 km/hr). These supersonic winds make up the fastest jet stream of its kind ever measured on a planet.
• ESO’s Very Large Telescope spotted part of the atmosphere of this planet is moving toward us at a high velocity while another part is moving away from us at the same speed.
• The fastest winds in our solar system are on Neptune. Those winds move at a comparatively “slow” 1,100 miles mph (1,800 km/hr).

ESO published this original article on January 21, 2025. Edits by EarthSky.

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!

Extreme winds on exoplanet reach 20,000 mph

Astronomers have discovered extremely powerful winds pummeling the equator of WASP-127b, a giant exoplanet. Reaching speeds up to 20,000 miles per hour (32,000 km/h), the winds make up the fastest jet stream of its kind ever measured on a planet. The discovery was made using the European Southern Observatory’s Very Large Telescope (ESO’s VLT) in Chile. It provides unique insights into the weather patterns of a distant world.

Artist’s concept of WASP-127b, a giant gas planet located about 500 light-years from Earth. The visualization of extreme winds on exoplanet WASP-127b shows how its newly discovered supersonic jet winds move around the planet’s equator. Image via ESO/ L. Calçada.

A windy, distant world

Tornadoes, cyclones and hurricanes wreak havoc on Earth. But scientists have now detected planetary winds on an entirely different scale, far outside the solar system. Ever since its discovery in 2016, astronomers have been investigating the weather on WASP-127b, a giant gas planet located over 500 light-years from Earth. The planet is slightly larger than Jupiter but has only a fraction of its mass, making it puffy. An international team of astronomers have now made an unexpected discovery: supersonic winds are raging on the planet.

Lisa Nortmann, a scientist at the University of Göttingen, Germany, and lead author of the study, said:

Part of the atmosphere of this planet is moving toward us at a high velocity while another part is moving away from us at the same speed. This signal shows us that there is a very fast, supersonic, jet wind around the planet’s equator.

At about 6 miles per second (or 9 km per second, which is close to a whopping 32,000 km/h), the jet winds move at nearly six times the speed at which the planet rotates. Nortmann said:

This is something we haven’t seen before. It is the fastest wind ever measured in a jet stream that goes around a planet. In comparison, the fastest wind ever measured in the solar system was found on Neptune, moving at ‘only’ 0.5 km per second (1,800 km/h).

The discovery of extreme winds on exoplanet WASP-127b

The team published their peer-reviewed research on January 21, 2025, in Astronomy & Astrophysics. They mapped the weather and make-up of WASP-127b using the CRIRES+ instrument on ESO’s VLT. By measuring how the light of the host star travels through the planet’s upper atmosphere, they managed to trace its composition. Their results confirm the presence of water vapor and carbon monoxide molecules in the planet’s atmosphere.

But when the team tracked the speed of this material in the atmosphere, they observed – much to their surprise – a double peak. This indicated that one side of the atmosphere is moving toward us and the other away from us at high speed. The researchers conclude that powerful jet stream winds around the equator would explain this unexpected result.

Further building up their weather map, the team also found that the poles are cooler than the rest of the planet. There is also a slight temperature difference between the morning and evening sides of WASP-127b. Fei Yan, a co-author of the study and a professor at the University of Science and Technology of China, said:

This shows that the planet has complex weather patterns just like Earth and other planets of our own system.

Advancing research on exoplanets

The field of exoplanet research is rapidly advancing. Up until a few years ago, astronomers could measure only the mass and the radius of planets outside the solar system. Today, telescopes like ESO’s VLT already allow scientists to map the weather on these distant worlds and analyze their atmospheres. David Cont from the Ludwig Maximilian University of Munich, Germany, and a co-author of the paper, said:

Understanding the dynamics of these exoplanets helps us explore mechanisms such as heat redistribution and chemical processes, improving our understanding of planet formation and potentially shedding light on the origins of our own solar system.

Interestingly, at present, studies like this can only be done by ground-based observatories. The instruments currently on space telescopes do not have the necessary velocity precision. ESO’s Extremely Large Telescope – which is under construction close to the VLT in Chile – and its ANDES instrument will allow researchers to delve even deeper into the weather patterns on far-away planets. Nortmann said:

This means that we can likely resolve even finer details of the wind patterns and expand this research to smaller, rocky planets.

Bottom line: Astronomers found extreme winds on exoplanet WASP-127b reach 20,000 mph (32,000 km/hr). These supersonic winds make up the fastest jet stream of its kind ever measured on a planet.

Via ESO

The post Extreme winds on exoplanet reach 20,000 mph first appeared on EarthSky.

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Astronomers found extreme winds on exoplanet WASP-127b reach 20,000 mph (32,000 km/hr). EarthSky’s Will Triggs explains in this short video.

• Extreme winds on exoplanet WASP-127b reach 20,000 mph (32,000 km/hr). These supersonic winds make up the fastest jet stream of its kind ever measured on a planet.
• ESO’s Very Large Telescope spotted part of the atmosphere of this planet is moving toward us at a high velocity while another part is moving away from us at the same speed.
• The fastest winds in our solar system are on Neptune. Those winds move at a comparatively “slow” 1,100 miles mph (1,800 km/hr).

ESO published this original article on January 21, 2025. Edits by EarthSky.

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!

Extreme winds on exoplanet reach 20,000 mph

Astronomers have discovered extremely powerful winds pummeling the equator of WASP-127b, a giant exoplanet. Reaching speeds up to 20,000 miles per hour (32,000 km/h), the winds make up the fastest jet stream of its kind ever measured on a planet. The discovery was made using the European Southern Observatory’s Very Large Telescope (ESO’s VLT) in Chile. It provides unique insights into the weather patterns of a distant world.

Artist’s concept of WASP-127b, a giant gas planet located about 500 light-years from Earth. The visualization of extreme winds on exoplanet WASP-127b shows how its newly discovered supersonic jet winds move around the planet’s equator. Image via ESO/ L. Calçada.

A windy, distant world

Tornadoes, cyclones and hurricanes wreak havoc on Earth. But scientists have now detected planetary winds on an entirely different scale, far outside the solar system. Ever since its discovery in 2016, astronomers have been investigating the weather on WASP-127b, a giant gas planet located over 500 light-years from Earth. The planet is slightly larger than Jupiter but has only a fraction of its mass, making it puffy. An international team of astronomers have now made an unexpected discovery: supersonic winds are raging on the planet.

Lisa Nortmann, a scientist at the University of Göttingen, Germany, and lead author of the study, said:

Part of the atmosphere of this planet is moving toward us at a high velocity while another part is moving away from us at the same speed. This signal shows us that there is a very fast, supersonic, jet wind around the planet’s equator.

At about 6 miles per second (or 9 km per second, which is close to a whopping 32,000 km/h), the jet winds move at nearly six times the speed at which the planet rotates. Nortmann said:

This is something we haven’t seen before. It is the fastest wind ever measured in a jet stream that goes around a planet. In comparison, the fastest wind ever measured in the solar system was found on Neptune, moving at ‘only’ 0.5 km per second (1,800 km/h).

The discovery of extreme winds on exoplanet WASP-127b

The team published their peer-reviewed research on January 21, 2025, in Astronomy & Astrophysics. They mapped the weather and make-up of WASP-127b using the CRIRES+ instrument on ESO’s VLT. By measuring how the light of the host star travels through the planet’s upper atmosphere, they managed to trace its composition. Their results confirm the presence of water vapor and carbon monoxide molecules in the planet’s atmosphere.

But when the team tracked the speed of this material in the atmosphere, they observed – much to their surprise – a double peak. This indicated that one side of the atmosphere is moving toward us and the other away from us at high speed. The researchers conclude that powerful jet stream winds around the equator would explain this unexpected result.

Further building up their weather map, the team also found that the poles are cooler than the rest of the planet. There is also a slight temperature difference between the morning and evening sides of WASP-127b. Fei Yan, a co-author of the study and a professor at the University of Science and Technology of China, said:

This shows that the planet has complex weather patterns just like Earth and other planets of our own system.

Advancing research on exoplanets

The field of exoplanet research is rapidly advancing. Up until a few years ago, astronomers could measure only the mass and the radius of planets outside the solar system. Today, telescopes like ESO’s VLT already allow scientists to map the weather on these distant worlds and analyze their atmospheres. David Cont from the Ludwig Maximilian University of Munich, Germany, and a co-author of the paper, said:

Understanding the dynamics of these exoplanets helps us explore mechanisms such as heat redistribution and chemical processes, improving our understanding of planet formation and potentially shedding light on the origins of our own solar system.

Interestingly, at present, studies like this can only be done by ground-based observatories. The instruments currently on space telescopes do not have the necessary velocity precision. ESO’s Extremely Large Telescope – which is under construction close to the VLT in Chile – and its ANDES instrument will allow researchers to delve even deeper into the weather patterns on far-away planets. Nortmann said:

This means that we can likely resolve even finer details of the wind patterns and expand this research to smaller, rocky planets.

Bottom line: Astronomers found extreme winds on exoplanet WASP-127b reach 20,000 mph (32,000 km/hr). These supersonic winds make up the fastest jet stream of its kind ever measured on a planet.

Via ESO

The post Extreme winds on exoplanet reach 20,000 mph first appeared on EarthSky.

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M41 is a faint star cluster near bright Sirius

View at EarthSky Community Photos. | Stephane Picard in Quispamsis, New Brunswick, Canada, took this image of a star cluster on March 4, 2022. Stephane wrote: “M41/NGC 2287, the Little Beehive Cluster in Canis Major. Directly south of Sirius (brightest star in the sky).” Thank you, Stephane!

Find the star cluster M41

Do you want to see an open star cluster? Then just look for nighttime’s brightest star, Sirius, in the constellation Canis Major the Greater Dog. A lovely star cluster – called Messier 41 or M41 – lies near Sirius. It’ll look like a fuzzy patch in the sky. If you can’t see the star cluster, it’s probably because your sky isn’t dark enough. So try aiming your binoculars at bright Sirius. You might glimpse the little star cluster in the same binocular field.

Sirius is easy to spot. It’s bright, brighter than any other star you’ll see in the evening sky now. You can be sure you’re looking at Sirius if Orion’s Belt – three stars in a short, straight row in the constellation Orion the Hunter – are pointing to it.

M41 lies about 4 degrees south of Sirius. Most stars look like pinpoints. But the cluster looks like a fuzzy spot, unlike a typical star. It shines at magnitude 4.5 – within the limit of vision to the unaided eye – so some people do see M41 with the eye alone in a dark sky. Individuals with particularly good vision have likely spotted it throughout human history.

M41 documented centuries ago

Sometime before 1654, the early astronomer Giovanni Battista Hodierna noticed M41 and placed it in his catalog of comets and other celestial objects. Then in the late 1700s, M41 was one of the objects that astronomer Charles Messier (1730-1817) thought could be mistaken for a comet. In fact, that’s when he was looking for comets, and compiled a list of these objects to avoid in his now-famous list of Messier objects.

Sirius, the sky’s brightest star, dominates the constellation of Canis Major the Greater Dog. The yellow dot below Sirius is M41. Image via Wikimedia Commons/ IAU/ Sky & Telescope.

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Messier 41 is an open cluster

M41 is an open star cluster made of sibling stars still moving together through space. They are loose collections of stars, located in the flat disk of our Milky Way galaxy, born from a single cloud of gas and dust in space. They are very beautiful when viewed through binoculars or a small telescope.

Like most open star clusters of its type, M41 is relatively young, probably between 190 and 240 million years old. By contrast, our sun is about 4 1/2 billion years old.

M41 lies 2,300 light years away. The cluster – whose true diameter in space covers about 25 light-years – contains about 100 stars including several red giants.

At mid-northern latitudes, Sirius and M41 stay out until roughly 4 a.m. local time at this time of year.

M41 is also sometimes called the Little Beehive, after the famous Beehive star cluster, also known as M44, in the constellation Cancer the Crab.

So enjoy Orion, the star Sirius and M41 on these January and February evenings. And by the way, there are over 100 of the so-called Messier objects or M-objects to find and enjoy. Today’s amateur astronomers consider them among the most prized objects to view through binoculars and small telescopes. Here’s a list of M-objects. Advanced amateurs can observe them all and can earn a Messier certificate from the Astronomical League.

Bottom line: No matter where you are on Earth, look for the sky’s brightest star, Sirius, in the months of January, February and March. If your sky is dark enough, notice the faint fuzzy object near the bright star Sirius. This object is called M41, and it’s a distant cluster of stars.

A planisphere is virtually indispensable for beginning stargazers. Order your EarthSky Planisphere today!

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View at EarthSky Community Photos. | Stephane Picard in Quispamsis, New Brunswick, Canada, took this image of a star cluster on March 4, 2022. Stephane wrote: “M41/NGC 2287, the Little Beehive Cluster in Canis Major. Directly south of Sirius (brightest star in the sky).” Thank you, Stephane!

Find the star cluster M41

Do you want to see an open star cluster? Then just look for nighttime’s brightest star, Sirius, in the constellation Canis Major the Greater Dog. A lovely star cluster – called Messier 41 or M41 – lies near Sirius. It’ll look like a fuzzy patch in the sky. If you can’t see the star cluster, it’s probably because your sky isn’t dark enough. So try aiming your binoculars at bright Sirius. You might glimpse the little star cluster in the same binocular field.

Sirius is easy to spot. It’s bright, brighter than any other star you’ll see in the evening sky now. You can be sure you’re looking at Sirius if Orion’s Belt – three stars in a short, straight row in the constellation Orion the Hunter – are pointing to it.

M41 lies about 4 degrees south of Sirius. Most stars look like pinpoints. But the cluster looks like a fuzzy spot, unlike a typical star. It shines at magnitude 4.5 – within the limit of vision to the unaided eye – so some people do see M41 with the eye alone in a dark sky. Individuals with particularly good vision have likely spotted it throughout human history.

M41 documented centuries ago

Sometime before 1654, the early astronomer Giovanni Battista Hodierna noticed M41 and placed it in his catalog of comets and other celestial objects. Then in the late 1700s, M41 was one of the objects that astronomer Charles Messier (1730-1817) thought could be mistaken for a comet. In fact, that’s when he was looking for comets, and compiled a list of these objects to avoid in his now-famous list of Messier objects.

Sirius, the sky’s brightest star, dominates the constellation of Canis Major the Greater Dog. The yellow dot below Sirius is M41. Image via Wikimedia Commons/ IAU/ Sky & Telescope.

Now on sale! The 2025 EarthSky lunar calendar. A unique and beautiful poster-sized calendar showing phases of the moon every night of the year. Treat yourself!

Messier 41 is an open cluster

M41 is an open star cluster made of sibling stars still moving together through space. They are loose collections of stars, located in the flat disk of our Milky Way galaxy, born from a single cloud of gas and dust in space. They are very beautiful when viewed through binoculars or a small telescope.

Like most open star clusters of its type, M41 is relatively young, probably between 190 and 240 million years old. By contrast, our sun is about 4 1/2 billion years old.

M41 lies 2,300 light years away. The cluster – whose true diameter in space covers about 25 light-years – contains about 100 stars including several red giants.

At mid-northern latitudes, Sirius and M41 stay out until roughly 4 a.m. local time at this time of year.

M41 is also sometimes called the Little Beehive, after the famous Beehive star cluster, also known as M44, in the constellation Cancer the Crab.

So enjoy Orion, the star Sirius and M41 on these January and February evenings. And by the way, there are over 100 of the so-called Messier objects or M-objects to find and enjoy. Today’s amateur astronomers consider them among the most prized objects to view through binoculars and small telescopes. Here’s a list of M-objects. Advanced amateurs can observe them all and can earn a Messier certificate from the Astronomical League.

Bottom line: No matter where you are on Earth, look for the sky’s brightest star, Sirius, in the months of January, February and March. If your sky is dark enough, notice the faint fuzzy object near the bright star Sirius. This object is called M41, and it’s a distant cluster of stars.

A planisphere is virtually indispensable for beginning stargazers. Order your EarthSky Planisphere today!

The post M41 is a faint star cluster near bright Sirius first appeared on EarthSky.

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Earth’s asteroid mini-moon a chunk of the moon?

Artist’s concept of an asteroid in space. Late last year, Earth acquired an asteroid mini-moon for a couple months. Now scientists said the asteroid is likely a chunk ejected from the moon during an impact. Image via NASA/ JPL-Caltech.

For two months late last year, Earth had a captured mini-moon, before it went back on its way around the sun. And now NASA said on January 22, 2025, that the little asteroid – named 2024 PT5 – is likely a chunk of our moon broken off in a past collision. A team of researchers believe the rock’s composition means a large impact ejected it from the moon’s surface.

The researchers published their peer-reviewed findings in Astrophysical Journal Letters on January 14, 2025.

Mini-moon was a piece of our moon

Teddy Kareta of Lowell Observatory in Arizona was lead author of the study. Kareta said:

We had a general idea that this asteroid may have come from the moon, but the smoking gun was when we found out that it was rich in silicate minerals. Not the kind that are seen on asteroids but those that have been found in lunar rock samples. It looks like it hasn’t been in space for very long, maybe just a few thousand years or so, as there’s a lack of space weathering that would have caused its spectrum to redden.

The researchers used the Lowell Discovery Telescope and the NASA Infrared Telescope Facility on Mauna Kea in Hawai’i to analyze the light reflected from the asteroid. That light didn’t match any known asteroid type. But it did look like what we know of the composition of our moon.

Analyzing the orbit of 2024 PT5

In addition to looking at the spectrum and composition of asteroid 2024 PT5, the researchers also analyzed the object’s orbit. They ruled out the object being space junk by how it was affected by solar radiation pressure. These little particles from our sun can give objects a push. Space debris, such as hollow rocket boosters, move more due to this push than natural objects such as asteroids. Co-author Oscar Fuentes-Muñoz of JPL said:

Space debris and space rocks move slightly differently in space. Human-made debris is usually relatively light and gets pushed around by the pressure of sunlight. That 2024 PT5 doesn’t move this way indicates it is much denser than space debris.

The 2nd asteroid from the moon

This is only the second asteroid known to come from the moon. In 2016, astronomers discovered asteroid 469219 Kamo’oalewa. While it also had an orbit similar to Earth’s, it never became a temporary mini-moon like 2024 PT5 did. Astronomers hope to find more asteroids from the moon, and maybe even match them to the craters they were ejected from. Kareta said:

This is a story about the moon as told by asteroid scientists. It’s a rare situation where we’ve gone out to study an asteroid but then strayed into new territory in terms of the questions we can ask of 2024 PT5.

Earth had an asteroid mini-moon for 2 months

Asteroid 2024 PT5 was a mini-moon of Earth from September 29 until November 25, 2024. However, the asteroid never completed one revolution of Earth, so it was considered a temporarily captured flyby as opposed to a temporarily captured orbiter. Asteroid PT5 is approximately 33 feet (10 meters) in size.

The ATLAS survey in South Africa discovered the asteroid on August 7, 2024.

Newly-discovered #asteroid 2024 PT5 is about to undergo a "mini-moon event" when its geocentric energy becomes negative from September 29 – November 25.https://t.co/sAo1qSRu3J pic.twitter.com/pVYAmSbkCF

— Tony Dunn (@tony873004) September 10, 2024

Asteroid mini-moon animation via Tony Dunn on X.

How did we get the asteroid mini-moon?

Asteroid 2024 PT5’s close approach to our planet at a relatively low velocity allowed Earth’s gravity to temporarily alter its path. But the sun eventually pulled it back into a heliocentric orbit. The asteroid had another somewhat close flyby of Earth on January 9, 2025, before:

leaving the neighborhood of Earth shortly afterward, until its next return in 2055.

From September 29 to November 25, 2024, Earth had an asteroid mini-moon. The newly discovered asteroid 2024 PT5 got close enough to Earth to be drawn in for a “temporarily captured flyby”. Image via Tony Dunn on X.

Bottom line: Earth had an asteroid mini-moon late last year for two months. Now scientists say that the mini-moon was likely a chunk of our moon ejected in an impact.

Source: On the Lunar Origin of Near-Earth Asteroid 2024 PT5

Source: A Two-month Mini-moon: 2024 PT5 Captured by Earth from September to November

Via JPL/NASA

Read more: Say goodbye to Earth’s mini-moon on February 1 and 2

The post Earth’s asteroid mini-moon a chunk of the moon? first appeared on EarthSky.

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Artist’s concept of an asteroid in space. Late last year, Earth acquired an asteroid mini-moon for a couple months. Now scientists said the asteroid is likely a chunk ejected from the moon during an impact. Image via NASA/ JPL-Caltech.

For two months late last year, Earth had a captured mini-moon, before it went back on its way around the sun. And now NASA said on January 22, 2025, that the little asteroid – named 2024 PT5 – is likely a chunk of our moon broken off in a past collision. A team of researchers believe the rock’s composition means a large impact ejected it from the moon’s surface.

The researchers published their peer-reviewed findings in Astrophysical Journal Letters on January 14, 2025.

Mini-moon was a piece of our moon

Teddy Kareta of Lowell Observatory in Arizona was lead author of the study. Kareta said:

We had a general idea that this asteroid may have come from the moon, but the smoking gun was when we found out that it was rich in silicate minerals. Not the kind that are seen on asteroids but those that have been found in lunar rock samples. It looks like it hasn’t been in space for very long, maybe just a few thousand years or so, as there’s a lack of space weathering that would have caused its spectrum to redden.

The researchers used the Lowell Discovery Telescope and the NASA Infrared Telescope Facility on Mauna Kea in Hawai’i to analyze the light reflected from the asteroid. That light didn’t match any known asteroid type. But it did look like what we know of the composition of our moon.

Analyzing the orbit of 2024 PT5

In addition to looking at the spectrum and composition of asteroid 2024 PT5, the researchers also analyzed the object’s orbit. They ruled out the object being space junk by how it was affected by solar radiation pressure. These little particles from our sun can give objects a push. Space debris, such as hollow rocket boosters, move more due to this push than natural objects such as asteroids. Co-author Oscar Fuentes-Muñoz of JPL said:

Space debris and space rocks move slightly differently in space. Human-made debris is usually relatively light and gets pushed around by the pressure of sunlight. That 2024 PT5 doesn’t move this way indicates it is much denser than space debris.

The 2nd asteroid from the moon

This is only the second asteroid known to come from the moon. In 2016, astronomers discovered asteroid 469219 Kamo’oalewa. While it also had an orbit similar to Earth’s, it never became a temporary mini-moon like 2024 PT5 did. Astronomers hope to find more asteroids from the moon, and maybe even match them to the craters they were ejected from. Kareta said:

This is a story about the moon as told by asteroid scientists. It’s a rare situation where we’ve gone out to study an asteroid but then strayed into new territory in terms of the questions we can ask of 2024 PT5.

Earth had an asteroid mini-moon for 2 months

Asteroid 2024 PT5 was a mini-moon of Earth from September 29 until November 25, 2024. However, the asteroid never completed one revolution of Earth, so it was considered a temporarily captured flyby as opposed to a temporarily captured orbiter. Asteroid PT5 is approximately 33 feet (10 meters) in size.

The ATLAS survey in South Africa discovered the asteroid on August 7, 2024.

Newly-discovered #asteroid 2024 PT5 is about to undergo a "mini-moon event" when its geocentric energy becomes negative from September 29 – November 25.https://t.co/sAo1qSRu3J pic.twitter.com/pVYAmSbkCF

— Tony Dunn (@tony873004) September 10, 2024

Asteroid mini-moon animation via Tony Dunn on X.

How did we get the asteroid mini-moon?

Asteroid 2024 PT5’s close approach to our planet at a relatively low velocity allowed Earth’s gravity to temporarily alter its path. But the sun eventually pulled it back into a heliocentric orbit. The asteroid had another somewhat close flyby of Earth on January 9, 2025, before:

leaving the neighborhood of Earth shortly afterward, until its next return in 2055.

From September 29 to November 25, 2024, Earth had an asteroid mini-moon. The newly discovered asteroid 2024 PT5 got close enough to Earth to be drawn in for a “temporarily captured flyby”. Image via Tony Dunn on X.

Bottom line: Earth had an asteroid mini-moon late last year for two months. Now scientists say that the mini-moon was likely a chunk of our moon ejected in an impact.

Source: On the Lunar Origin of Near-Earth Asteroid 2024 PT5

Source: A Two-month Mini-moon: 2024 PT5 Captured by Earth from September to November

Via JPL/NASA

Read more: Say goodbye to Earth’s mini-moon on February 1 and 2

The post Earth’s asteroid mini-moon a chunk of the moon? first appeared on EarthSky.

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Lakes on Mars had ripples! They must have been ice-free

View larger. | Artist’s illustration of an ancient lake in Gale crater on Mars. NASA’s Curiosity rover has found that at least some lakes on Mars were ice-free and had small wind-blown ripples. Image via Kevin Gill (CC BY 2.0).

• Mars had lakes on its surface billions of years ago, scientists believe. But was this liquid water on Mars open to the air, with waves, or were the lakes covered in ice?
• The Mars rover Curiosity has found evidence for ripples on lakes in Gale crater. As on Earth, the ripples must have been driven by winds.
• So the lakes weren’t covered in ice, this evidence suggests. If so, conditions must have been warm enough on Mars for ice-free lakes, which, this study suggests, existed on Mars for longer then previously thought.

Were lakes on Mars frozen solid?

We know that lakes existed on Mars’ surface billions of years ago. But scientists have debated whether the lakes were open to the air or covered by a layer of ice. Now, researchers in the U.S., U.K. and France have released a new study showing that at least some Martian lakes must have been ice-free. The researchers said on January 15, 2025, that NASA’s Curiosity rover on Mars has now examined layers in rock outcrops in Gale crater. The ancient rocks show evidence of wind-driven ripples on former Martian lakes or ponds.

The researchers published their peer-reviewed findings in Science Advances, also on January 15.

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!

Researchers from @Caltech have identified ancient wave ripples on Mars, indicating the presence of long-gone, ice-free ponds and lakes.

These ripples, discovered by NASA's Curiosity rover in the Gale Crater region, are small undulations formed by wind-driven water, suggesting… pic.twitter.com/1XiGVqozZz

— Erika ? (@ExploreCosmos_) January 16, 2025

Wind-blown ripples on ancient Mars lakes

Evidence of ripples on lakes or other bodies of water can be preserved in rock layers. The Curiosity rover has found such evidence in Gale crater on Mars. The mission team estimates these rocks to be about 3.7 billion years old. That’s nearly as old as our sun; its estimated age is 4.5 billion years. So the rocks are very old. And Curiosity – which has been exploring Gale crater on Mars since 2012 – first found the two sets of ripples in 2022. The first set, at the Prow rock outcrop, is in a region that once contained wind-blown sand dunes. The second set is nearby, in the Amapari Marker Band rock outcrop.

Interestingly, the Amapari Marker Band ripples formed a bit later in Mars’ history than the Prow ripples. The scientists said this means that conditions for their formation – i.e. for liquid water – were suitable at multiple times.

In addition, these ripples formed during a period of Mars’ past when the planet was becoming drier and losing its water. Or at least that’s what scientists thought. This new evidence would suggest that Mars was able to hold on to its water at least a bit longer than previously estimated. Lead author Claire Mondro at the California Institute of Technology (Caltech) in California said:

Extending the length of time that liquid water was present extends the possibilities for microbial habitability later into Mars’ history.

The ripples were small, only about 0.2 inches (6 millimeters) high and spaced less than 2 inches (4 to 5 centimeters) apart. This suggests the lake was shallow, less than 6.5 feet (2 meters) deep.

View larger. | Ripples preserved in the Prow rock outcrop. Image via Mondro et al./ NASA/ JPL-Caltech/ MSSS.

Ice-free lakes and ponds

The findings are significant for a couple of reasons. Not only do they show that – as has previous evidence from Curiosity – that there were lakes and ponds in Gale crater, but that they were ice-free. Some climate models for Mars’ past suggest that any lakes on Mars probably were covered by ice. But the new study suggests otherwise. Mondro said:

The shape of the ripples could only have been formed under water that was open to the atmosphere and acted upon by wind.

This is important, because it means conditions must have been warm enough for lakes to exist without a covering of ice. As the paper stated:

Symmetrical wave ripples identified with NASA’s Curiosity rover in ancient lake deposits at Gale crater provide a key paleoclimate constraint for early Mars. At the time of ripple formation, climate conditions must have supported ice-free liquid water on the surface of Mars. Their presence suggests formation in a shallow-water (<2 meters) setting that was open to the atmosphere, which requires atmospheric conditions that allow stable surface water.

View larger. | Ripples preserved in the Amapari Marker Band rock outcrop. Image via Mondro et al./ NASA/ JPL-Caltech/ MSSS.

Previous evidence for ripples

The Opportunity rover in Meridiani Planum also discovered evidence for water ripples after its mission began in 2004. It wasn’t clear, however, whether that water actually formed standing lakes or ponds. Now, the confirmation from Curiosity for ripples on ice-free lakes is an important discovery. John Grotzinger at Caltech, former project scientist for Curiosity, explained:

The discovery of wave ripples is an important advance for Mars paleoclimate science. We have been searching for these features since the Opportunity and Spirit landers began their missions in 2004. Earlier missions, beginning with Opportunity in 2004, discovered ripples formed by water flowing across the surface of ancient Mars, but it was uncertain if that water ever pooled to form lakes or shallow seas. The Curiosity rover discovered evidence for long-lived ancient lakes in 2014, and now 10 years later Curiosity has discovered ancient lakes that were free of ice, offering an important insight into the planet’s early climate.

Since the lakes were warm enough to not freeze over, could there have been any microbes swimming in them? We don’t know, but it’s an exciting possibility to contemplate!

Bottom line: At least some ancient lakes on Mars were ice-free. NASA’s Curiosity rover discovered evidence for small wind-blown ripples on the former lakes in Gale crater.

Source: Wave ripples formed in ancient, ice-free lakes in Gale crater, Mars

Via Caltech

Read more: Ancient Mars lake was larger than any on Earth

Read more: Did this Mars rock once lie along an ancient lakeshore?

The post Lakes on Mars had ripples! They must have been ice-free first appeared on EarthSky.

from EarthSky https://ift.tt/JfA35XV

View larger. | Artist’s illustration of an ancient lake in Gale crater on Mars. NASA’s Curiosity rover has found that at least some lakes on Mars were ice-free and had small wind-blown ripples. Image via Kevin Gill (CC BY 2.0).

• Mars had lakes on its surface billions of years ago, scientists believe. But was this liquid water on Mars open to the air, with waves, or were the lakes covered in ice?
• The Mars rover Curiosity has found evidence for ripples on lakes in Gale crater. As on Earth, the ripples must have been driven by winds.
• So the lakes weren’t covered in ice, this evidence suggests. If so, conditions must have been warm enough on Mars for ice-free lakes, which, this study suggests, existed on Mars for longer then previously thought.

Were lakes on Mars frozen solid?

We know that lakes existed on Mars’ surface billions of years ago. But scientists have debated whether the lakes were open to the air or covered by a layer of ice. Now, researchers in the U.S., U.K. and France have released a new study showing that at least some Martian lakes must have been ice-free. The researchers said on January 15, 2025, that NASA’s Curiosity rover on Mars has now examined layers in rock outcrops in Gale crater. The ancient rocks show evidence of wind-driven ripples on former Martian lakes or ponds.

The researchers published their peer-reviewed findings in Science Advances, also on January 15.

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!

Researchers from @Caltech have identified ancient wave ripples on Mars, indicating the presence of long-gone, ice-free ponds and lakes.

These ripples, discovered by NASA's Curiosity rover in the Gale Crater region, are small undulations formed by wind-driven water, suggesting… pic.twitter.com/1XiGVqozZz

— Erika ? (@ExploreCosmos_) January 16, 2025

Wind-blown ripples on ancient Mars lakes

Evidence of ripples on lakes or other bodies of water can be preserved in rock layers. The Curiosity rover has found such evidence in Gale crater on Mars. The mission team estimates these rocks to be about 3.7 billion years old. That’s nearly as old as our sun; its estimated age is 4.5 billion years. So the rocks are very old. And Curiosity – which has been exploring Gale crater on Mars since 2012 – first found the two sets of ripples in 2022. The first set, at the Prow rock outcrop, is in a region that once contained wind-blown sand dunes. The second set is nearby, in the Amapari Marker Band rock outcrop.

Interestingly, the Amapari Marker Band ripples formed a bit later in Mars’ history than the Prow ripples. The scientists said this means that conditions for their formation – i.e. for liquid water – were suitable at multiple times.

In addition, these ripples formed during a period of Mars’ past when the planet was becoming drier and losing its water. Or at least that’s what scientists thought. This new evidence would suggest that Mars was able to hold on to its water at least a bit longer than previously estimated. Lead author Claire Mondro at the California Institute of Technology (Caltech) in California said:

Extending the length of time that liquid water was present extends the possibilities for microbial habitability later into Mars’ history.

The ripples were small, only about 0.2 inches (6 millimeters) high and spaced less than 2 inches (4 to 5 centimeters) apart. This suggests the lake was shallow, less than 6.5 feet (2 meters) deep.

View larger. | Ripples preserved in the Prow rock outcrop. Image via Mondro et al./ NASA/ JPL-Caltech/ MSSS.

Ice-free lakes and ponds

The findings are significant for a couple of reasons. Not only do they show that – as has previous evidence from Curiosity – that there were lakes and ponds in Gale crater, but that they were ice-free. Some climate models for Mars’ past suggest that any lakes on Mars probably were covered by ice. But the new study suggests otherwise. Mondro said:

The shape of the ripples could only have been formed under water that was open to the atmosphere and acted upon by wind.

This is important, because it means conditions must have been warm enough for lakes to exist without a covering of ice. As the paper stated:

Symmetrical wave ripples identified with NASA’s Curiosity rover in ancient lake deposits at Gale crater provide a key paleoclimate constraint for early Mars. At the time of ripple formation, climate conditions must have supported ice-free liquid water on the surface of Mars. Their presence suggests formation in a shallow-water (<2 meters) setting that was open to the atmosphere, which requires atmospheric conditions that allow stable surface water.

View larger. | Ripples preserved in the Amapari Marker Band rock outcrop. Image via Mondro et al./ NASA/ JPL-Caltech/ MSSS.

Previous evidence for ripples

The Opportunity rover in Meridiani Planum also discovered evidence for water ripples after its mission began in 2004. It wasn’t clear, however, whether that water actually formed standing lakes or ponds. Now, the confirmation from Curiosity for ripples on ice-free lakes is an important discovery. John Grotzinger at Caltech, former project scientist for Curiosity, explained:

The discovery of wave ripples is an important advance for Mars paleoclimate science. We have been searching for these features since the Opportunity and Spirit landers began their missions in 2004. Earlier missions, beginning with Opportunity in 2004, discovered ripples formed by water flowing across the surface of ancient Mars, but it was uncertain if that water ever pooled to form lakes or shallow seas. The Curiosity rover discovered evidence for long-lived ancient lakes in 2014, and now 10 years later Curiosity has discovered ancient lakes that were free of ice, offering an important insight into the planet’s early climate.

Since the lakes were warm enough to not freeze over, could there have been any microbes swimming in them? We don’t know, but it’s an exciting possibility to contemplate!

Bottom line: At least some ancient lakes on Mars were ice-free. NASA’s Curiosity rover discovered evidence for small wind-blown ripples on the former lakes in Gale crater.

Source: Wave ripples formed in ancient, ice-free lakes in Gale crater, Mars

Via Caltech

Read more: Ancient Mars lake was larger than any on Earth

Read more: Did this Mars rock once lie along an ancient lakeshore?

The post Lakes on Mars had ripples! They must have been ice-free first appeared on EarthSky.

from EarthSky https://ift.tt/JfA35XV

What are hole-punch clouds, aka fallstreak holes?

View at EarthSky Community Photos. | Kris Hazelbaker in Grangeville, Idaho, captured this image on January 20, 2025. Kris wrote: “I was driving across the prairie here and this fallstreak or hole-punch cloud was showing blue sky through the stratus clouds.” Thank you, Kris! Read more on these hole-punch clouds below.

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

Fallstreak holes or hole-punch clouds

You’ve surely seen many clouds in the sky. But jets can cause a different type of cloud feature, called hole-punch clouds, aka fallstreak holes. They look like abrupt clearings in an altocumulus cloud layer, often circular patches of clear sky punched into the surrounding clouds. How do they form?

According to weather.com, an altocumulus cloud layer is:

… composed of small water droplets that are below freezing called ‘supercooled water droplets.’ If ice crystals can form in the layer of supercooled droplets, they will grow rapidly and shrink or possibly evaporate the droplets completely.

Studies, including this one by Andrew Heymsfield and collaborators, have shown that aircraft passing through these cloud layers can trigger the formation of the heavier ice crystals, which fall to Earth and then leave the circular void in the blanket of clouds.

View at EarthSky Community Photos. | Saranya Kumar in Woodbridge, New Jersey, caught this image of a hole-punch cloud – aka a fallstreak hole – on December 15, 2021. Airplanes make hole-punch clouds. Also, notice the rainbow-like patch in the cloud, with the sun off to the right? That colored patch looks to us like a sundog. Saranya said: “Awesome view.” Indeed! Thank you, Saranya!

Jets make fallstreak holes

The study concluded that aircraft propellers and wings cause the formation of those initial ice crystals. There are zones of locally low pressure along the wing and propeller tips that allow the air to expand and cool well below the original temperature of the cloud layer, forming ice crystals.

Andrew Heymsfield of the National Center for Atmospheric Research spoke with EarthSky some years ago, when his study first appeared. He told us:

This whole idea of jet aircraft making these features has to do with cooling of air over the wings that generates ice.

His team found that – at lower altitudes – jets can punch holes in clouds and make small amounts of rain and snow. As a plane flies through mid-level clouds, it forces air to expand rapidly and cool. Water droplets in the cloud freeze to ice and then turn to snow as they fall. The gap expands to create spectacular holes in the clouds. He said:

We found an exemplary case of hole-punch clouds over Texas. From satellite imagery you could see holes just pocketing the sky, holes and long channels where aircraft had been flying at that level of the cloud for a while.

Hole punch cloud via visible satellite and cell phone. pic.twitter.com/m5b63SsI8i

— Anton Falco (@AntonFalcoWx) October 30, 2022

The physics behind hole-punch clouds

Heymsfield used a weather forecast model developed at NCAR – and radar images of clouds from NASA’s CloudSat satellite – to explain the physics of how jet aircraft make hole-punch clouds.

Heymsfield’s team found that every measurable commercial jet aircraft, private jet aircraft and military jets as well as turbo props were producing these holes. He said a hole-punch cloud expands for hours after being created. Major airports, where there’s a lot of aircraft traffic, would be a good place to study cloud holes. Heymsfield said:

What we decided to do was look at major airports around the world, especially where there’s low cloud cover and cold clouds in the wintertime, and found that the frequency of occurrence suitable for this process to occur is reasonably high, on the order of three to five percent. In the winter months, it’s probably two to three times higher, 10 to 15 percent.

Our friend @EmilyFlair captured these photos from JFK Airport in New York back on December 15.

They show “hole punch clouds,” more technically known as fallstreak holed. They result when airplanes fly though supercooled water droplets and give them something to freeze onto/fall. pic.twitter.com/ukVNMH7sMN

— MyRadar Weather (@MyRadarWX) February 9, 2022

A view from 35,000 feet

Heymsfield said people who look out their airplane window in flight can see for themselves how the wing changes a cloud.

When an aircraft lands or takes off sometimes – especially in humid, tropical areas – you see a little veil of clouds over the wings of the aircraft. And basically, what’s happening over the wings of the aircraft, there’s cooling. And the cooling produces a cloud.

It’s basically a super-cooled cloud. It’s just like a fog you see at the ground except that its temperature is zero degrees centigrade [32 F]. So, in that process of expanding, the air expands over the wing and cools. And that cooling can be as much as 20 degrees centigrade [68 F].

The cooling of air over the wings generates ice, said Heymsfield.

About the Texas incident where satellite imagery showed many hole-punch openings and channels, Heymsfield said:

What we found was that there were about a hundred of these little features. We decided to, first of all, identify their location and see if we could link them to particular aircraft. Then the second thing we did was say, okay, why do these long channels last for the period of time it would take for a satellite to take a snapshot of them? We got high-time-resolution satellite imagery and were able then to track these features, these holes, and watch them develop with time, watch how they developed.

Send us your fallstreak holes!

Have you captured a photo of a hole-punch cloud or fallstreak hole? Send it to us at EarthSky Community Photos!

Li Cammy in Jordan, Hong Kong, captured this photo of a square-ish hole in the clouds, writing: "Square fallstreak hole with CZA." Thank you, Li! ???

See more photos from EarthSky readers in EarthSky Community Photos, and send in your own images, too: https://t.co/YODz3atk7G pic.twitter.com/JwBN20mlBT

— EarthSky (@earthskyscience) December 13, 2021

Bottom Line: Jets create fallstreak holes or hole-punch clouds. They’re a type of cloud with a flat layer interrupted by a big hole, often with wisps at the center. Want to see these clouds for yourself? Hang out by an airport in winter when stratus clouds are in the atmosphere and you might get lucky!

Read more: Media we love: The book A Cloud a Day

The post What are hole-punch clouds, aka fallstreak holes? first appeared on EarthSky.

from EarthSky https://ift.tt/sOKWkM7

View at EarthSky Community Photos. | Kris Hazelbaker in Grangeville, Idaho, captured this image on January 20, 2025. Kris wrote: “I was driving across the prairie here and this fallstreak or hole-punch cloud was showing blue sky through the stratus clouds.” Thank you, Kris! Read more on these hole-punch clouds below.

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

Fallstreak holes or hole-punch clouds

You’ve surely seen many clouds in the sky. But jets can cause a different type of cloud feature, called hole-punch clouds, aka fallstreak holes. They look like abrupt clearings in an altocumulus cloud layer, often circular patches of clear sky punched into the surrounding clouds. How do they form?

According to weather.com, an altocumulus cloud layer is:

… composed of small water droplets that are below freezing called ‘supercooled water droplets.’ If ice crystals can form in the layer of supercooled droplets, they will grow rapidly and shrink or possibly evaporate the droplets completely.

Studies, including this one by Andrew Heymsfield and collaborators, have shown that aircraft passing through these cloud layers can trigger the formation of the heavier ice crystals, which fall to Earth and then leave the circular void in the blanket of clouds.

View at EarthSky Community Photos. | Saranya Kumar in Woodbridge, New Jersey, caught this image of a hole-punch cloud – aka a fallstreak hole – on December 15, 2021. Airplanes make hole-punch clouds. Also, notice the rainbow-like patch in the cloud, with the sun off to the right? That colored patch looks to us like a sundog. Saranya said: “Awesome view.” Indeed! Thank you, Saranya!

Jets make fallstreak holes

The study concluded that aircraft propellers and wings cause the formation of those initial ice crystals. There are zones of locally low pressure along the wing and propeller tips that allow the air to expand and cool well below the original temperature of the cloud layer, forming ice crystals.

Andrew Heymsfield of the National Center for Atmospheric Research spoke with EarthSky some years ago, when his study first appeared. He told us:

This whole idea of jet aircraft making these features has to do with cooling of air over the wings that generates ice.

His team found that – at lower altitudes – jets can punch holes in clouds and make small amounts of rain and snow. As a plane flies through mid-level clouds, it forces air to expand rapidly and cool. Water droplets in the cloud freeze to ice and then turn to snow as they fall. The gap expands to create spectacular holes in the clouds. He said:

We found an exemplary case of hole-punch clouds over Texas. From satellite imagery you could see holes just pocketing the sky, holes and long channels where aircraft had been flying at that level of the cloud for a while.

Hole punch cloud via visible satellite and cell phone. pic.twitter.com/m5b63SsI8i

— Anton Falco (@AntonFalcoWx) October 30, 2022

The physics behind hole-punch clouds

Heymsfield used a weather forecast model developed at NCAR – and radar images of clouds from NASA’s CloudSat satellite – to explain the physics of how jet aircraft make hole-punch clouds.

Heymsfield’s team found that every measurable commercial jet aircraft, private jet aircraft and military jets as well as turbo props were producing these holes. He said a hole-punch cloud expands for hours after being created. Major airports, where there’s a lot of aircraft traffic, would be a good place to study cloud holes. Heymsfield said:

What we decided to do was look at major airports around the world, especially where there’s low cloud cover and cold clouds in the wintertime, and found that the frequency of occurrence suitable for this process to occur is reasonably high, on the order of three to five percent. In the winter months, it’s probably two to three times higher, 10 to 15 percent.

Our friend @EmilyFlair captured these photos from JFK Airport in New York back on December 15.

They show “hole punch clouds,” more technically known as fallstreak holed. They result when airplanes fly though supercooled water droplets and give them something to freeze onto/fall. pic.twitter.com/ukVNMH7sMN

— MyRadar Weather (@MyRadarWX) February 9, 2022

A view from 35,000 feet

Heymsfield said people who look out their airplane window in flight can see for themselves how the wing changes a cloud.

When an aircraft lands or takes off sometimes – especially in humid, tropical areas – you see a little veil of clouds over the wings of the aircraft. And basically, what’s happening over the wings of the aircraft, there’s cooling. And the cooling produces a cloud.

It’s basically a super-cooled cloud. It’s just like a fog you see at the ground except that its temperature is zero degrees centigrade [32 F]. So, in that process of expanding, the air expands over the wing and cools. And that cooling can be as much as 20 degrees centigrade [68 F].

The cooling of air over the wings generates ice, said Heymsfield.

About the Texas incident where satellite imagery showed many hole-punch openings and channels, Heymsfield said:

What we found was that there were about a hundred of these little features. We decided to, first of all, identify their location and see if we could link them to particular aircraft. Then the second thing we did was say, okay, why do these long channels last for the period of time it would take for a satellite to take a snapshot of them? We got high-time-resolution satellite imagery and were able then to track these features, these holes, and watch them develop with time, watch how they developed.

Send us your fallstreak holes!

Have you captured a photo of a hole-punch cloud or fallstreak hole? Send it to us at EarthSky Community Photos!

Li Cammy in Jordan, Hong Kong, captured this photo of a square-ish hole in the clouds, writing: "Square fallstreak hole with CZA." Thank you, Li! ???

See more photos from EarthSky readers in EarthSky Community Photos, and send in your own images, too: https://t.co/YODz3atk7G pic.twitter.com/JwBN20mlBT

— EarthSky (@earthskyscience) December 13, 2021

Bottom Line: Jets create fallstreak holes or hole-punch clouds. They’re a type of cloud with a flat layer interrupted by a big hole, often with wisps at the center. Want to see these clouds for yourself? Hang out by an airport in winter when stratus clouds are in the atmosphere and you might get lucky!

Read more: Media we love: The book A Cloud a Day

The post What are hole-punch clouds, aka fallstreak holes? first appeared on EarthSky.

from EarthSky https://ift.tt/sOKWkM7