Newly formed moon crater is once-in-a-century discovery

Sometime between April 11 and May 22, 2024, a comet or asteroid the size of a 3- to 6-story building hit the moon. But we didn’t know about it until someone scanning Lunar Reconnaissance Orbiter maps spotted it. It’s the largest newly formed crater yet found in the solar system. The newly formed moon crater has been named McGetchin Crater. Image via NASA/ GSFC/ Intuitive Machines.

• NASA’s Lunar Reconnaissance Orbiter has spotted a new lunar crater. It’s the largest newly formed crater yet found in the solar system.
• The crater formed between April 11 and May 22, 2024, when a rock the size of a 3- to 6-story building hit the moon. It’s about 728 feet wide and 141 feet deep (222 m wide and 43 m deep). This size of lunar impact only occurs about once a century or longer.
• The impact disturbed the lunar soil over a much larger area. It created a 4-mile-wide zone (6.4 km) that is about 16 F (8.8 C) colder at night because the loosened soil doesn’t retain heat as well.

NASA published this original story on September 16, 2026. Edits by EarthSky.

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

Newly formed moon crater is once-in-a-century discovery

It started as a routine data-quality check. But as Robert Wagner – an image processing specialist with NASA’s Lunar Reconnaissance Orbiter (LRO) – scanned a giant moon map on his computer screen, an unusually large bright spot circled by a dark halo caught his eye. It implied that surface material in that area had been shaken up. He said:

I just stopped, dropped everything, and started looking into what that spot was.

By comparing before and after images of the moon, Wagner realized he had discovered the largest newly formed crater ever found in the solar system. This discovery highlights the value of NASA’s moon orbiter data in studying a dynamic landscape as the agency advances a sustained human presence and expanded scientific and commercial activity on the moon.

It was officially named McGetchin after pioneering lunar scientist Tom McGetchin. The crater formed on the moon’s eastern edge sometime between April 11 and May 22, 2024, after a comet or asteroid the size of a three- to six-story building hit the surface.

The crash left a crater 728 feet (222 meters) wide, spanning the length of two football fields. And at 141 feet (43 meters) deep, the crater could fit three vertically stacked yellow school buses.

Scientists estimate that an impact of this magnitude happens on the moon about once in a century or even longer.

The researchers published two papers on the crater. The first was published by Science Advances on September 16, 2026. The peer-reviewed Science Advances also published the second paper on September 16, 2026.

The moon takes some hits

The Lunar Reconnaissance Orbiter has been circling the moon for more than 17 years. It uses its seven instruments to map the topography, surface composition, temperature and radiation environment there. The spacecraft’s team has identified at least 1,000 new impact craters throughout the mission and flagged 100,000 more surface changes from an object smashing into the moon or from the debris that flung out after.

With no atmosphere to slow them or burn them up, space rocks and other objects easily reach the lunar surface. Most are much smaller compared to the object that carved out McGetchin crater. The smallest craters scientists can distinguish from LRO images are about 30 feet wide, the length of a three-story building laid on its side. The rocks that make those craters are about 43 inches wide (110 cm), the size of a monster-truck tire. Scientists estimate that impacts of this scale produce about 140 new craters across the moon each year. But most new ones are from microscopic projectiles that leave holes too small to identify in orbital images.

What a cool impact!

With its numerous instruments, the spacecraft can observe changes to the lunar surface that aren’t apparent in the Orbiter’s images alone. After the crater discovery, scientists working with the craft’s thermal instrument, Diviner, made follow-up observations of the site. They found a 4-mile-wide area around the crater that is about 16 degrees F (8.8 C) cooler at night than its surroundings.

Researchers said the cooling happens because the impact fluffs up the regolith around the crater, making it less dense and therefore less able to retain heat. The large extent of this “cold spot” is striking, scientists said, because it shows that impacts can modify the moon’s surface far beyond the crater itself. These physical changes could affect how rover wheels interact with the surface, for instance.

View of before the formation of McGetchin Crater on the moon’s eastern limb and after. The Lunar Reconnaissance Orbiter’s thermal instrument, Diviner, captured the 2 images. Experts are calling this a once-in-a-century collision. The dark blue shows a “cold spot,” which happens because an impact fluffs up regolith around a crater, making it less dense. Therefore it’s less able to retain heat. Image via NASA Goddard/ UCLA/ JHU APL.

Road to discovery of newly formed moon crater

The Lunar Reconnaissance Orbiter collects images from about 60 miles (96 km) above the moon as it loops from pole to pole. The system includes two cameras that capture high-resolution black-and-white images and one camera for moderate-resolution multispectral images. Over the years and thousands of passes, scientists have built maps detailed enough to spot not only new craters, but also landslides, landers, seismic faults and even hints of lava tubes.

Mission scientists regularly analyze close-up images of small portions of the moon’s surface from the Narrow-Angle Camera. Using these images, they look for changes that are typically less than 30 feet across. But every few years the team searches for large (wider than 150 feet) features by creating global moon maps and comparing them to older versions.

That’s what Wagner was doing on October 24, 2025, when he came across McGetchin. Using images from the Orbiter’s Wide-Angle Camera – which captures broad views with pixels the size of football fields – he stacked hundreds of “before” and “after” frames with software designed to highlight change. Anything that stayed the same turned gray while anything different showed up as bright or dark patches.

One spot stood out

While the process sounds straightforward, spotting real craters requires a lot of manual work. The software flags every tiny shift in lighting or shadow, generating hundreds of false alarms. For this reason, Wagner typically verifies the software, looking for small fuzzy halos around pixel-wide bright points. These indicate splashes of regolith around a new crater.

Spanning hundreds of pixels, McGetchin stood out immediately. Wagner said:

It was by far the most obvious impact debris pattern I’ve ever seen in one of these images.

After his discovery, scientists turned to the Narrow-Angle Camera, which takes much sharper views at about 3 feet per pixel. This camera’s close-up images, taken as LRO flew over the impact site again, revealed the crater size, shape and how the surrounding terrain was affected. These images also helped researchers estimate the size and force of the rock fragment that formed the new crater, details that should appear in a future paper.

Bottom line: Sometime in early 2024, a space rock slammed into the moon, creating a brand new crater in the lunar surface. The newly formed moon crater is about 728 feet wide and 141 feet deep.

Source: A new 222-m diameter lunar crater

Source: New lunar crater reveals extensive distal regolith modification

Via NASA

Read more: Asteroid 2024 YR4 won’t hit the moon after all

The post Newly formed moon crater is once-in-a-century discovery first appeared on EarthSky.

from EarthSky https://ift.tt/HjNp136

Sometime between April 11 and May 22, 2024, a comet or asteroid the size of a 3- to 6-story building hit the moon. But we didn’t know about it until someone scanning Lunar Reconnaissance Orbiter maps spotted it. It’s the largest newly formed crater yet found in the solar system. The newly formed moon crater has been named McGetchin Crater. Image via NASA/ GSFC/ Intuitive Machines.

• NASA’s Lunar Reconnaissance Orbiter has spotted a new lunar crater. It’s the largest newly formed crater yet found in the solar system.
• The crater formed between April 11 and May 22, 2024, when a rock the size of a 3- to 6-story building hit the moon. It’s about 728 feet wide and 141 feet deep (222 m wide and 43 m deep). This size of lunar impact only occurs about once a century or longer.
• The impact disturbed the lunar soil over a much larger area. It created a 4-mile-wide zone (6.4 km) that is about 16 F (8.8 C) colder at night because the loosened soil doesn’t retain heat as well.

NASA published this original story on September 16, 2026. Edits by EarthSky.

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

Newly formed moon crater is once-in-a-century discovery

It started as a routine data-quality check. But as Robert Wagner – an image processing specialist with NASA’s Lunar Reconnaissance Orbiter (LRO) – scanned a giant moon map on his computer screen, an unusually large bright spot circled by a dark halo caught his eye. It implied that surface material in that area had been shaken up. He said:

I just stopped, dropped everything, and started looking into what that spot was.

By comparing before and after images of the moon, Wagner realized he had discovered the largest newly formed crater ever found in the solar system. This discovery highlights the value of NASA’s moon orbiter data in studying a dynamic landscape as the agency advances a sustained human presence and expanded scientific and commercial activity on the moon.

It was officially named McGetchin after pioneering lunar scientist Tom McGetchin. The crater formed on the moon’s eastern edge sometime between April 11 and May 22, 2024, after a comet or asteroid the size of a three- to six-story building hit the surface.

The crash left a crater 728 feet (222 meters) wide, spanning the length of two football fields. And at 141 feet (43 meters) deep, the crater could fit three vertically stacked yellow school buses.

Scientists estimate that an impact of this magnitude happens on the moon about once in a century or even longer.

The researchers published two papers on the crater. The first was published by Science Advances on September 16, 2026. The peer-reviewed Science Advances also published the second paper on September 16, 2026.

The moon takes some hits

The Lunar Reconnaissance Orbiter has been circling the moon for more than 17 years. It uses its seven instruments to map the topography, surface composition, temperature and radiation environment there. The spacecraft’s team has identified at least 1,000 new impact craters throughout the mission and flagged 100,000 more surface changes from an object smashing into the moon or from the debris that flung out after.

With no atmosphere to slow them or burn them up, space rocks and other objects easily reach the lunar surface. Most are much smaller compared to the object that carved out McGetchin crater. The smallest craters scientists can distinguish from LRO images are about 30 feet wide, the length of a three-story building laid on its side. The rocks that make those craters are about 43 inches wide (110 cm), the size of a monster-truck tire. Scientists estimate that impacts of this scale produce about 140 new craters across the moon each year. But most new ones are from microscopic projectiles that leave holes too small to identify in orbital images.

What a cool impact!

With its numerous instruments, the spacecraft can observe changes to the lunar surface that aren’t apparent in the Orbiter’s images alone. After the crater discovery, scientists working with the craft’s thermal instrument, Diviner, made follow-up observations of the site. They found a 4-mile-wide area around the crater that is about 16 degrees F (8.8 C) cooler at night than its surroundings.

Researchers said the cooling happens because the impact fluffs up the regolith around the crater, making it less dense and therefore less able to retain heat. The large extent of this “cold spot” is striking, scientists said, because it shows that impacts can modify the moon’s surface far beyond the crater itself. These physical changes could affect how rover wheels interact with the surface, for instance.

View of before the formation of McGetchin Crater on the moon’s eastern limb and after. The Lunar Reconnaissance Orbiter’s thermal instrument, Diviner, captured the 2 images. Experts are calling this a once-in-a-century collision. The dark blue shows a “cold spot,” which happens because an impact fluffs up regolith around a crater, making it less dense. Therefore it’s less able to retain heat. Image via NASA Goddard/ UCLA/ JHU APL.

Road to discovery of newly formed moon crater

The Lunar Reconnaissance Orbiter collects images from about 60 miles (96 km) above the moon as it loops from pole to pole. The system includes two cameras that capture high-resolution black-and-white images and one camera for moderate-resolution multispectral images. Over the years and thousands of passes, scientists have built maps detailed enough to spot not only new craters, but also landslides, landers, seismic faults and even hints of lava tubes.

Mission scientists regularly analyze close-up images of small portions of the moon’s surface from the Narrow-Angle Camera. Using these images, they look for changes that are typically less than 30 feet across. But every few years the team searches for large (wider than 150 feet) features by creating global moon maps and comparing them to older versions.

That’s what Wagner was doing on October 24, 2025, when he came across McGetchin. Using images from the Orbiter’s Wide-Angle Camera – which captures broad views with pixels the size of football fields – he stacked hundreds of “before” and “after” frames with software designed to highlight change. Anything that stayed the same turned gray while anything different showed up as bright or dark patches.

One spot stood out

While the process sounds straightforward, spotting real craters requires a lot of manual work. The software flags every tiny shift in lighting or shadow, generating hundreds of false alarms. For this reason, Wagner typically verifies the software, looking for small fuzzy halos around pixel-wide bright points. These indicate splashes of regolith around a new crater.

Spanning hundreds of pixels, McGetchin stood out immediately. Wagner said:

It was by far the most obvious impact debris pattern I’ve ever seen in one of these images.

After his discovery, scientists turned to the Narrow-Angle Camera, which takes much sharper views at about 3 feet per pixel. This camera’s close-up images, taken as LRO flew over the impact site again, revealed the crater size, shape and how the surrounding terrain was affected. These images also helped researchers estimate the size and force of the rock fragment that formed the new crater, details that should appear in a future paper.

Bottom line: Sometime in early 2024, a space rock slammed into the moon, creating a brand new crater in the lunar surface. The newly formed moon crater is about 728 feet wide and 141 feet deep.

Source: A new 222-m diameter lunar crater

Source: New lunar crater reveals extensive distal regolith modification

Via NASA

Read more: Asteroid 2024 YR4 won’t hit the moon after all

The post Newly formed moon crater is once-in-a-century discovery first appeared on EarthSky.

from EarthSky https://ift.tt/HjNp136

Yes, there’s an aurora season, and it’s here

View at EarthSky Community Photos. | JD Smith in Clay County, Minnesota, caught this beautiful image on November 12, 2025. Thank you, JD! Auroras are more frequent around the equinoxes. But why? Read about the aurora season below.

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

When is aurora season?

Yes, there is an aurora season, which comes around the fall and spring equinox each year. This pattern in nature – auroras increasing twice a year – has been known to scientists for more than a century.

We know that storms and eruptions on the sun cause disturbances in Earth’s magnetic field called geomagnetic storms. And we know the sun itself has cycles, including the famous 11-year solar cycle. That cycle appears to have peaked in late 2024, and the sun is still relatively active.

But an 11-year cycle is not a twice-yearly cycle. Why would geomagnetic storms increase twice a year?

As it turns out, it’s all about magnetism, geometry and something called the Russell-McPherron effect.

Read more: Forms of aurora: Arcs, curtains, coronas and more

Aurora season: Early studies

And it’s something nature-watchers have studied for a long time. Aloysius Cortie, an English Jesuit astronomer who conducted sun studies around the turn of the last century, published the first notable journal paper on the link between equinoxes and auroras in the year 1912.

Then, in 1940, the mathematician Sydney Chapman and his German colleague Julius Bartels included another discussion of the twice-yearly aurora season in their classic book Geomagnetism. This book became the standard textbook on Earth’s magnetism for several decades.

Later, a solar physicist – David Hathaway of NASA’s Marshall Space Flight Center in Huntsville, Alabama – created an updated plot showing the same seasonal pattern. Hathaway’s plot is below:

David Hathaway of NASA created an updated plot showing a seasonal variation in Earth’s magnetic storms, similar to the one that had been published in 1940. This one shows geomagnetic activity from 1932 to 2002. It shows a twice-a-year increase in the geomagnetic storms that cause auroras. Image via David Hathaway. Used with permission.

The Russell-McPherron effect

Over the years, scientist put forth several models to explain the twice-a-year variation in geomagnetic storms. An enduring explanation comes from Christopher Russell and Robert McPherron, both of UCLA. Their 1973 paper on the subject was titled Semiannual variation of geomagnetic activity.

Although their model explaining the seasonal variation in aurora frequency didn’t explain everything perfectly, it did show a physical connection between the geometry of Earth’s magnetic field and the magnetic field carried to Earth from the sun by the solar wind. And that is why, since the 1973 paper, the term Russell-McPherron effect has been used for seasonal auroras.

View at EarthSky Community Photos. | Robynanne Cash-Howard captured these auroras in Highbridge, Wisconsin, on November 12, 2025. Thank you, Robynanne!

So what’s the connection?

The Bz component. You know how a magnet always comes with two poles: a north pole and a south pole? Solar magnetic fields – carried to Earth via the solar wind – also have a north and south pole. Russell and McPherron showed that the “north-south” component of the sun’s magnetic field – called the Bz component by solar physicists – goes up and down over the year, in a way corresponding to the wobbling of Earth’s axis. They showed these fluctuations are largest during the equinoxes. Geomagnetic storms – and therefore auroras – happen most often when the “north-south” component of the solar wind is more or less opposite the “north-south” component of Earth’s own magnetic field.

It happens because – just as when two bar magnets oriented oppositely attract one another – so opposite Bz components attract. They open up a hole in Earth’s magnetic field, which allows the solar wind to flow more easily toward Earth’s magnetic poles.

When this happens, presto, we have auroras!

Check here for EarthSky’s daily sun news.

Sun on the left, Earth on the right. Not to scale. The sun’s magnetic field – carried by the solar wind – is between them. Note that the Bx and By components are oriented parallel to the ecliptic (Earth-sun plane). The 3rd component, called the Bz component, is perpendicular to the ecliptic. Geomagnetic storms – and therefore auroras – happen most often when the Bz component of the solar wind is more or less opposite the Bz component of Earth’s own magnetic field. The tilt of the Earth in relationship to the Earth-sun plane – around the time of an equinox – is what causes them to be opposite. Image via EarthSky.

The equinoctial effect

There is another factor that comes into place that also increases aurora activity during equinoxes. It’s called the equinoctial effect. Equinoctial just means happening at or near the time of an equinox.

Many of the competing models to that of Russell and McPherron are based on the equinoctial effect. It’s not as strong as the effect mentioned above, but it does add to the equinox-aurora connection.

Here’s how it works. During equinoxes, Earth’s magnetic poles (north and south) are at right angles to the flowing solar wind two times a day. During these times, the solar wind is effectively stronger, enhancing magnetic storms. As the seasons change, the poles either point more toward or away from the sun, reducing this effect.

See what we mean? Magnetism … and the geometry of objects in space.

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

Will you see colors in aurora? Or do you need a camera?

Magnetism and geometry in aurora season

So there is a reason why auroras are more frequent around the equinoxes. Researchers have been studying the phenomenon for over 100 years and still are studying it. They might not agree on all the details, but they do agree that the cause relates to the magnetic fields of both the sun and the Earth, working in conjunction with the sun-Earth geometry at a given time of year, as Earth moves in its orbit.

As meteorologist Curtis Grevenitz wrote this in his WeatherWise article for KTVH-News in Helena, Montana:

It is not just a coincidence that these two beautiful phenomena have a relationship.

Aurora photos from the EarthSky community

View at EarthSky Community Photos. | David Cox captured this beautiful view of auroras over Deep River, Ontario, on September 14, 2025, after an unexpected G3 (strong) geomagnetic storm. Thank you, David!

View at EarthSky Community Photos. | EarthSky’s Marcy Curran in Cheyenne, Wyoming, took this photo on September 14, 2025, and wrote: “We’ve got an allsky camera at our house and I noticed green on the northern horizon. I knew it had to be an aurora, so I headed outside and could see a glow to the north. My cell phone picked up more detail and color.” Stunning! Thank you, Marcy!

View at EarthSky Community Photos. | Thea Schenk in Eidsfjord, Norway, captured this aurora in the form of curtains or drapes on October 1, 2025. Thank you, Thea!

More aurora photos

View at EarthSky Community Photos. | Earll Johnson captured this beautiful auroral display on October 19, 2025 from a plane over Davis Strait in Greenland and wrote: “I used the native smart phone camera. I pulled down the shade to minimize reflections.” Beautiful photo Earll! Many thanks!

View at EarthSky Community Photos. | Steven Karsh in Kananaskis, Alberta, sent us this photo of the auroras on October 1, 2025. Many thanks, Steve!

What are these weird aurora blobs? Explainer here

To our readers and community

We invite all of our readers to send us your recent photos. We love to see them! View our community photo page, or submit your image here.

Bottom line: There’s an aurora season around the March and September equinoxes each year, due to the way the magnetic fields of the sun and the Earth work in conjunction with sun-Earth geometry.

Check our daily sun news

Read more:

Amazing aurora photos capture the ‘sky on fire’

Auroras everywhere!

Auroras on May 10-11, 2024, wowed millions! Pics here

The post Yes, there’s an aurora season, and it’s here first appeared on EarthSky.

from EarthSky https://ift.tt/c3gWjYK

View at EarthSky Community Photos. | JD Smith in Clay County, Minnesota, caught this beautiful image on November 12, 2025. Thank you, JD! Auroras are more frequent around the equinoxes. But why? Read about the aurora season below.

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

When is aurora season?

Yes, there is an aurora season, which comes around the fall and spring equinox each year. This pattern in nature – auroras increasing twice a year – has been known to scientists for more than a century.

We know that storms and eruptions on the sun cause disturbances in Earth’s magnetic field called geomagnetic storms. And we know the sun itself has cycles, including the famous 11-year solar cycle. That cycle appears to have peaked in late 2024, and the sun is still relatively active.

But an 11-year cycle is not a twice-yearly cycle. Why would geomagnetic storms increase twice a year?

As it turns out, it’s all about magnetism, geometry and something called the Russell-McPherron effect.

Read more: Forms of aurora: Arcs, curtains, coronas and more

Aurora season: Early studies

And it’s something nature-watchers have studied for a long time. Aloysius Cortie, an English Jesuit astronomer who conducted sun studies around the turn of the last century, published the first notable journal paper on the link between equinoxes and auroras in the year 1912.

Then, in 1940, the mathematician Sydney Chapman and his German colleague Julius Bartels included another discussion of the twice-yearly aurora season in their classic book Geomagnetism. This book became the standard textbook on Earth’s magnetism for several decades.

Later, a solar physicist – David Hathaway of NASA’s Marshall Space Flight Center in Huntsville, Alabama – created an updated plot showing the same seasonal pattern. Hathaway’s plot is below:

David Hathaway of NASA created an updated plot showing a seasonal variation in Earth’s magnetic storms, similar to the one that had been published in 1940. This one shows geomagnetic activity from 1932 to 2002. It shows a twice-a-year increase in the geomagnetic storms that cause auroras. Image via David Hathaway. Used with permission.

The Russell-McPherron effect

Over the years, scientist put forth several models to explain the twice-a-year variation in geomagnetic storms. An enduring explanation comes from Christopher Russell and Robert McPherron, both of UCLA. Their 1973 paper on the subject was titled Semiannual variation of geomagnetic activity.

Although their model explaining the seasonal variation in aurora frequency didn’t explain everything perfectly, it did show a physical connection between the geometry of Earth’s magnetic field and the magnetic field carried to Earth from the sun by the solar wind. And that is why, since the 1973 paper, the term Russell-McPherron effect has been used for seasonal auroras.

View at EarthSky Community Photos. | Robynanne Cash-Howard captured these auroras in Highbridge, Wisconsin, on November 12, 2025. Thank you, Robynanne!

So what’s the connection?

The Bz component. You know how a magnet always comes with two poles: a north pole and a south pole? Solar magnetic fields – carried to Earth via the solar wind – also have a north and south pole. Russell and McPherron showed that the “north-south” component of the sun’s magnetic field – called the Bz component by solar physicists – goes up and down over the year, in a way corresponding to the wobbling of Earth’s axis. They showed these fluctuations are largest during the equinoxes. Geomagnetic storms – and therefore auroras – happen most often when the “north-south” component of the solar wind is more or less opposite the “north-south” component of Earth’s own magnetic field.

It happens because – just as when two bar magnets oriented oppositely attract one another – so opposite Bz components attract. They open up a hole in Earth’s magnetic field, which allows the solar wind to flow more easily toward Earth’s magnetic poles.

When this happens, presto, we have auroras!

Check here for EarthSky’s daily sun news.

Sun on the left, Earth on the right. Not to scale. The sun’s magnetic field – carried by the solar wind – is between them. Note that the Bx and By components are oriented parallel to the ecliptic (Earth-sun plane). The 3rd component, called the Bz component, is perpendicular to the ecliptic. Geomagnetic storms – and therefore auroras – happen most often when the Bz component of the solar wind is more or less opposite the Bz component of Earth’s own magnetic field. The tilt of the Earth in relationship to the Earth-sun plane – around the time of an equinox – is what causes them to be opposite. Image via EarthSky.

The equinoctial effect

There is another factor that comes into place that also increases aurora activity during equinoxes. It’s called the equinoctial effect. Equinoctial just means happening at or near the time of an equinox.

Many of the competing models to that of Russell and McPherron are based on the equinoctial effect. It’s not as strong as the effect mentioned above, but it does add to the equinox-aurora connection.

Here’s how it works. During equinoxes, Earth’s magnetic poles (north and south) are at right angles to the flowing solar wind two times a day. During these times, the solar wind is effectively stronger, enhancing magnetic storms. As the seasons change, the poles either point more toward or away from the sun, reducing this effect.

See what we mean? Magnetism … and the geometry of objects in space.

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

Will you see colors in aurora? Or do you need a camera?

Magnetism and geometry in aurora season

So there is a reason why auroras are more frequent around the equinoxes. Researchers have been studying the phenomenon for over 100 years and still are studying it. They might not agree on all the details, but they do agree that the cause relates to the magnetic fields of both the sun and the Earth, working in conjunction with the sun-Earth geometry at a given time of year, as Earth moves in its orbit.

As meteorologist Curtis Grevenitz wrote this in his WeatherWise article for KTVH-News in Helena, Montana:

It is not just a coincidence that these two beautiful phenomena have a relationship.

Aurora photos from the EarthSky community

View at EarthSky Community Photos. | David Cox captured this beautiful view of auroras over Deep River, Ontario, on September 14, 2025, after an unexpected G3 (strong) geomagnetic storm. Thank you, David!

View at EarthSky Community Photos. | EarthSky’s Marcy Curran in Cheyenne, Wyoming, took this photo on September 14, 2025, and wrote: “We’ve got an allsky camera at our house and I noticed green on the northern horizon. I knew it had to be an aurora, so I headed outside and could see a glow to the north. My cell phone picked up more detail and color.” Stunning! Thank you, Marcy!

View at EarthSky Community Photos. | Thea Schenk in Eidsfjord, Norway, captured this aurora in the form of curtains or drapes on October 1, 2025. Thank you, Thea!

More aurora photos

View at EarthSky Community Photos. | Earll Johnson captured this beautiful auroral display on October 19, 2025 from a plane over Davis Strait in Greenland and wrote: “I used the native smart phone camera. I pulled down the shade to minimize reflections.” Beautiful photo Earll! Many thanks!

View at EarthSky Community Photos. | Steven Karsh in Kananaskis, Alberta, sent us this photo of the auroras on October 1, 2025. Many thanks, Steve!

What are these weird aurora blobs? Explainer here

To our readers and community

We invite all of our readers to send us your recent photos. We love to see them! View our community photo page, or submit your image here.

Bottom line: There’s an aurora season around the March and September equinoxes each year, due to the way the magnetic fields of the sun and the Earth work in conjunction with sun-Earth geometry.

Check our daily sun news

Read more:

Amazing aurora photos capture the ‘sky on fire’

Auroras everywhere!

Auroras on May 10-11, 2024, wowed millions! Pics here

The post Yes, there’s an aurora season, and it’s here first appeared on EarthSky.

from EarthSky https://ift.tt/c3gWjYK

1st adult T. rex trackway found by high school teacher

The 4 footprints in a newly discovered T. rex trackway span about 23 feet (7 meters) in the Hell Creek Formation in North Dakota. Image via Tyler Lyson/ Denver Museum of Nature & Science.

Love wildlife and the natural world? Get the latest animal stories – as well as space and night sky updates – delivered to your inbox.

High school teacher finds 1st-ever adult T. rex trackway

A Colorado high school science teacher, Kent Hups, was volunteering on a dig in North Dakota with the Denver Museum of Nature & Science when he made a remarkable discovery. He spotted a Tyrannosaurus rex footprint, and then soon discovered three more, forming a trackway. It’s the first known discovery of an adult T. rex trackway. The footprints are preserved in sandstone at the Hell Creek Formation and are about 66.5 million years old.

The Denver Museum of Nature & Science said on September 9, 2026, the trackway extends for 23 feet (7 meters). These T. rex footprints allow researchers a glimpse of the ferocious predator in motion.

Hups, who became a co-author of the paper, said:

As a teacher, I’m always telling my students that science starts with curiosity, passion and careful observation. I never imagined that could lead me to a discovery like this.

The researchers published their peer-reviewed study of the T. rex trackway in the Journal of Vertebrate Paleontology on September 8, 2026.

Kent Hups, at center in the bright blue shirt and tan hat, measures one of the footprints of the trackway as part of the excavation team. Image via Tyler Lyson/ Denver Museum of Nature & Science.

A closer look at the T. rex trackway

The T. rex trackway consists of four large footprints. Each footprint is roughly 3 feet (1 meter) long. The footprints include two from the left foot and two from the right. The researchers were able to estimate that the T. rex was walking at a speed of about 3.5 to 4.5 miles per hour (5.6 to 7.2 kilometers per hour). That’s about the pace of a brisk human walk.

The tracks are part of the Hell Creek Formation. This is a famous fossil-rich site that preserves rocks and fossils from the final part of the Cretaceous.

This side view shows the 4 footsteps of the trackway in the lighter brown soil where the researchers excavated them. Image via Tyler Lyson/ Denver Museum of Nature & Science.

Why are the footprints raised?

Normally when we think of footprints, we think of depressions in the ground. And that’s how these started out, too. The dinosaur stepped into a soft mud and made an indent in the ground. Later, the footprint pooled with water and then sand or mud washed into the depression, filling it.

Eventually, that sediment hardened. And over millions of years, the filled-in footprint becomes rock. With even more time, softer rock that was around the surrounding footprints erodes away. In this case, what’s left behind is the harder sediment that had filled in the footprints. So what you see today is essentially an inverted footprint: a natural cast of the original track.

Ancient footprints are also preserved in other ways. Sometimes it’s the ground the dino stepped on that remains harder than subsequent layers. In those cases, you do have a preserved indentation of a footprint, such as in Ouray, Colorado.

Watch more: Hike along these dinosaur tracks in Colorado

Get a better perspective of the T. rex trackway in this video. Video via Peter Falkingham/ Denver Museum of Nature & Science.

How do scientists know it was a T. rex?

There are several clues pointing to the trackway belonging to a T. rex. First is that the footprints themselves are huge. Also, the narrow shape of the toes suggests they are from a T. rex. Plus, the area around the trackway is rich in T. rex fossils.

In fact, scientists have found individual footprints in this area before that they have attributed to adult T. rexes. But this is the first sequence of footprints — a trackway — that they believe is from a T. rex.

Co-author Tyler Lyson of the Denver Museum of Nature & Science said:

Bones tell us an enormous amount about these animals, but footprints capture a moment of behavior. With a trackway, we can actually follow an animal as it moved across the landscape. That is incredibly rare for T. rexes.

Scientists scanned the tracks in 3D

The researchers have used high-resolution 3D surface scanning to document the footprints and the entire trackway. Eventually, they plan to excavate the tracks themselves to display in the Denver Museum of Nature & Science.

The scans were able to produce such a detailed digital model of the tracks that the lead author never even saw them in person. Peter Falkingham is a professor of paleobiology at Liverpool John Moores University and a dinosaur track expert. He said:

The technology we’re able to apply in the digital age means my colleagues could scan the tracks in the field and then send the 3D information over to me to visualize on my computer and in VR, enabling me to take as close a look as they did in person.

You will soon be able to see the tracks for yourself if you visit the Denver Museum of Nature & Science.

This illustration shows what it might have looked like when the T. rex left behind its footprints in the mud. Image via Andrey Atuchin/ Denver Museum of Nature & Science.

Bottom line: A high school teacher discovered four footprints that make up the first-ever known T. rex trackway. He discovered it at Hell Creek Formation in North Dakota.

Source: A large tridactyl trackway from the Upper Cretaceous Hell Creek Formation of North Dakota, likely attributable to an adult Tyrannosaurus rex

Via Denver Museum of Nature & Science

Via Taylor & Francis

Read more: Rare juvenile T. rex discovered by young fossil hunters

Read more: Why did big, fierce T. Rex have such tiny arms?

The post 1st adult T. rex trackway found by high school teacher first appeared on EarthSky.

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The 4 footprints in a newly discovered T. rex trackway span about 23 feet (7 meters) in the Hell Creek Formation in North Dakota. Image via Tyler Lyson/ Denver Museum of Nature & Science.

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High school teacher finds 1st-ever adult T. rex trackway

A Colorado high school science teacher, Kent Hups, was volunteering on a dig in North Dakota with the Denver Museum of Nature & Science when he made a remarkable discovery. He spotted a Tyrannosaurus rex footprint, and then soon discovered three more, forming a trackway. It’s the first known discovery of an adult T. rex trackway. The footprints are preserved in sandstone at the Hell Creek Formation and are about 66.5 million years old.

The Denver Museum of Nature & Science said on September 9, 2026, the trackway extends for 23 feet (7 meters). These T. rex footprints allow researchers a glimpse of the ferocious predator in motion.

Hups, who became a co-author of the paper, said:

As a teacher, I’m always telling my students that science starts with curiosity, passion and careful observation. I never imagined that could lead me to a discovery like this.

The researchers published their peer-reviewed study of the T. rex trackway in the Journal of Vertebrate Paleontology on September 8, 2026.

Kent Hups, at center in the bright blue shirt and tan hat, measures one of the footprints of the trackway as part of the excavation team. Image via Tyler Lyson/ Denver Museum of Nature & Science.

A closer look at the T. rex trackway

The T. rex trackway consists of four large footprints. Each footprint is roughly 3 feet (1 meter) long. The footprints include two from the left foot and two from the right. The researchers were able to estimate that the T. rex was walking at a speed of about 3.5 to 4.5 miles per hour (5.6 to 7.2 kilometers per hour). That’s about the pace of a brisk human walk.

The tracks are part of the Hell Creek Formation. This is a famous fossil-rich site that preserves rocks and fossils from the final part of the Cretaceous.

This side view shows the 4 footsteps of the trackway in the lighter brown soil where the researchers excavated them. Image via Tyler Lyson/ Denver Museum of Nature & Science.

Why are the footprints raised?

Normally when we think of footprints, we think of depressions in the ground. And that’s how these started out, too. The dinosaur stepped into a soft mud and made an indent in the ground. Later, the footprint pooled with water and then sand or mud washed into the depression, filling it.

Eventually, that sediment hardened. And over millions of years, the filled-in footprint becomes rock. With even more time, softer rock that was around the surrounding footprints erodes away. In this case, what’s left behind is the harder sediment that had filled in the footprints. So what you see today is essentially an inverted footprint: a natural cast of the original track.

Ancient footprints are also preserved in other ways. Sometimes it’s the ground the dino stepped on that remains harder than subsequent layers. In those cases, you do have a preserved indentation of a footprint, such as in Ouray, Colorado.

Watch more: Hike along these dinosaur tracks in Colorado

Get a better perspective of the T. rex trackway in this video. Video via Peter Falkingham/ Denver Museum of Nature & Science.

How do scientists know it was a T. rex?

There are several clues pointing to the trackway belonging to a T. rex. First is that the footprints themselves are huge. Also, the narrow shape of the toes suggests they are from a T. rex. Plus, the area around the trackway is rich in T. rex fossils.

In fact, scientists have found individual footprints in this area before that they have attributed to adult T. rexes. But this is the first sequence of footprints — a trackway — that they believe is from a T. rex.

Co-author Tyler Lyson of the Denver Museum of Nature & Science said:

Bones tell us an enormous amount about these animals, but footprints capture a moment of behavior. With a trackway, we can actually follow an animal as it moved across the landscape. That is incredibly rare for T. rexes.

Scientists scanned the tracks in 3D

The researchers have used high-resolution 3D surface scanning to document the footprints and the entire trackway. Eventually, they plan to excavate the tracks themselves to display in the Denver Museum of Nature & Science.

The scans were able to produce such a detailed digital model of the tracks that the lead author never even saw them in person. Peter Falkingham is a professor of paleobiology at Liverpool John Moores University and a dinosaur track expert. He said:

The technology we’re able to apply in the digital age means my colleagues could scan the tracks in the field and then send the 3D information over to me to visualize on my computer and in VR, enabling me to take as close a look as they did in person.

You will soon be able to see the tracks for yourself if you visit the Denver Museum of Nature & Science.

This illustration shows what it might have looked like when the T. rex left behind its footprints in the mud. Image via Andrey Atuchin/ Denver Museum of Nature & Science.

Bottom line: A high school teacher discovered four footprints that make up the first-ever known T. rex trackway. He discovered it at Hell Creek Formation in North Dakota.

Source: A large tridactyl trackway from the Upper Cretaceous Hell Creek Formation of North Dakota, likely attributable to an adult Tyrannosaurus rex

Via Denver Museum of Nature & Science

Via Taylor & Francis

Read more: Rare juvenile T. rex discovered by young fossil hunters

Read more: Why did big, fierce T. Rex have such tiny arms?

The post 1st adult T. rex trackway found by high school teacher first appeared on EarthSky.

from EarthSky https://ift.tt/BF6Tfph

Equinox fun: Track the sun’s shift now until the solstice

View at EarthSky Community Photos. | Rupesh Sangoi in Mumbai, India, took and combined photos of the sunrise throughout the year. The image shows how the point where the sun rises shifts along the horizon between the June solstice and the December solstice, passing through the equinoxes. Rupesh wrote: “Did this for over a year, at sunrise.” Glorious composite, Rupesh! Thank you. Read more about equinox fun below.

The September equinox will arrive on September 23, 2026, at 0:05 UTC (19:05 p.m. CDT on September 22).

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

Equinox fun: Track the sunrise or sunset point

The sun’s movement from day to day along your horizon — at the sunrise or sunset point — is most noticeable around the equinoxes. And many streets in the U.S. and in other parts of the world are oriented either north-south or east-west. So, just by looking out the doorway of your home, you might easily be able to watch the progress of the sun as it slides from north to south in the weeks and months following the September equinox.

On the equinox, the sun rises directly in the east and sets directly in the west. You can see it move quickly further north each day afterward. No grid of streets to help you? Try tracking the sun’s progress along the horizon by placing bits of tape on an east- or west-facing window of your home. Or just find a clear spot — a place where you can see the horizon — and stand in the same spot whenever you watch the sunrise or sunset. You’ll notice the sun’s movement with respect to trees and other objects in the foreground.

Just be sure to observe from the exact same location every day. It’s enough to note the sunrise or sunset point every week or 10 days. You’ll easily see the sun’s southward shift between now and the December solstice.

Are you a photographer? Submit a composite image of the sun’s shift between now and the December solstice to EarthSky.

Then track between the solstices

What happens at the solstice? At mid-northern latitudes, there’s a two- to three-week time period where you probably won’t discern any movement of the sun along the horizon. That’s where the word solstice comes from. Solstice = sun still.

How much does it move?

We received a question from a reader about the movement of the sunset or sunrise along the horizon as Earth moves between seasons. They wrote:

Hello, I’m curious to know how far the sun moves north or south along the horizon each day? Like half its width? A quarter of its width?

The answer is that the degrees of the sun’s movement along the horizon depend on two things:

• The time of the year.
• Your latitude.

It’s all about your latitude

For example, at around 40 degrees north latitude (Denver, Colorado; island of Sardinia, Italy; Beijing, China), the sun pretty much rises due east and sets due west on the day of the March equinox. Two weeks later, the sun rises about 7 degrees north of due east and sets about 7 degrees north of due west. Because the sun’s diameter equals 1/2 degree, that means the sun has been traveling its own diameter (14 days x 1/2 degree = 7 degrees) northward daily.

At 65 degrees north latitude (Fairbanks, Alaska; Siberia; Iceland), the sun also rises and sets close to due east and due west on the day of the equinox. But two weeks later, the sun rises and sets about 14 degrees north of due east and west. So, at this far-northern latitude, the sun moves about one degree (two sun-diameters) along the horizon daily during this two-week period after the March equinox.

You can track the position of the sunset (or sunrise) location along the horizon during the different seasons. Image via EarthSky.

Bottom line: The amount of the sun’s movement along your horizon — at sunrise or sunset — varies with the time of year and with your latitude. It’s most perceptible around the equinoxes and least around the solstices.

Read more: The equinox sun rises due east and sets due west

Read more: See the year’s fastest sunsets and sunrises around equinoxes

The post Equinox fun: Track the sun’s shift now until the solstice first appeared on EarthSky.

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View at EarthSky Community Photos. | Rupesh Sangoi in Mumbai, India, took and combined photos of the sunrise throughout the year. The image shows how the point where the sun rises shifts along the horizon between the June solstice and the December solstice, passing through the equinoxes. Rupesh wrote: “Did this for over a year, at sunrise.” Glorious composite, Rupesh! Thank you. Read more about equinox fun below.

The September equinox will arrive on September 23, 2026, at 0:05 UTC (19:05 p.m. CDT on September 22).

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

Equinox fun: Track the sunrise or sunset point

The sun’s movement from day to day along your horizon — at the sunrise or sunset point — is most noticeable around the equinoxes. And many streets in the U.S. and in other parts of the world are oriented either north-south or east-west. So, just by looking out the doorway of your home, you might easily be able to watch the progress of the sun as it slides from north to south in the weeks and months following the September equinox.

On the equinox, the sun rises directly in the east and sets directly in the west. You can see it move quickly further north each day afterward. No grid of streets to help you? Try tracking the sun’s progress along the horizon by placing bits of tape on an east- or west-facing window of your home. Or just find a clear spot — a place where you can see the horizon — and stand in the same spot whenever you watch the sunrise or sunset. You’ll notice the sun’s movement with respect to trees and other objects in the foreground.

Just be sure to observe from the exact same location every day. It’s enough to note the sunrise or sunset point every week or 10 days. You’ll easily see the sun’s southward shift between now and the December solstice.

Are you a photographer? Submit a composite image of the sun’s shift between now and the December solstice to EarthSky.

Then track between the solstices

What happens at the solstice? At mid-northern latitudes, there’s a two- to three-week time period where you probably won’t discern any movement of the sun along the horizon. That’s where the word solstice comes from. Solstice = sun still.

How much does it move?

We received a question from a reader about the movement of the sunset or sunrise along the horizon as Earth moves between seasons. They wrote:

Hello, I’m curious to know how far the sun moves north or south along the horizon each day? Like half its width? A quarter of its width?

The answer is that the degrees of the sun’s movement along the horizon depend on two things:

• The time of the year.
• Your latitude.

It’s all about your latitude

For example, at around 40 degrees north latitude (Denver, Colorado; island of Sardinia, Italy; Beijing, China), the sun pretty much rises due east and sets due west on the day of the March equinox. Two weeks later, the sun rises about 7 degrees north of due east and sets about 7 degrees north of due west. Because the sun’s diameter equals 1/2 degree, that means the sun has been traveling its own diameter (14 days x 1/2 degree = 7 degrees) northward daily.

At 65 degrees north latitude (Fairbanks, Alaska; Siberia; Iceland), the sun also rises and sets close to due east and due west on the day of the equinox. But two weeks later, the sun rises and sets about 14 degrees north of due east and west. So, at this far-northern latitude, the sun moves about one degree (two sun-diameters) along the horizon daily during this two-week period after the March equinox.

You can track the position of the sunset (or sunrise) location along the horizon during the different seasons. Image via EarthSky.

Bottom line: The amount of the sun’s movement along your horizon — at sunrise or sunset — varies with the time of year and with your latitude. It’s most perceptible around the equinoxes and least around the solstices.

Read more: The equinox sun rises due east and sets due west

Read more: See the year’s fastest sunsets and sunrises around equinoxes

The post Equinox fun: Track the sun’s shift now until the solstice first appeared on EarthSky.

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JUICE mission to fly by Earth in late September

This is an artist’s impression of the JUICE mission, which will target Jupiter’s icy moons. In this view, JUICE passes over Ganymede with Jupiter in the background. In order to get there, JUICE must first make 2 more flybys of Earth for gravity assists. Image via ESA (acknowledgement: ATG Medialab).

JUICE mission will fly by Earth in late September

The JUICE mission — which stands for JUpiter Icy Moons Explorer — is on its way to Jupiter, where it will explore its ocean-bearing moons. But its path to Jupiter is not straight. In fact, JUICE will swing by Earth in late September to get a gravity assist. This will be the third of four planned gravity assists to slingshot the spacecraft toward our solar system’s largest planet.

At the moment, ESA puts the date of the flyby as September 27. The countdown for the upcoming Earth flyby according to the ticker at ESA’s website more specifically puts the flyby at around 6:45 a.m. CDT on Monday, September 28, 2026. If this timing has revisions over the next couple weeks, we will update you!

ESA does not currently have a livestream planned for the event. But during the last Earth flyby, it did provide real-time updates.

JUICE launched to space in 2023. Its first gravity assist flyby was the first ever maneuver of its kind. On August 19 and 20, 2024, it swung past both the moon and then Earth. The flyby of the moon and Earth was technically a braking maneuver. It served to line JUICE up for a Venus flyby, where the successful gravity assist sped up the spacecraft, or gave it the juice, if you will. The Venus flyby was on August 31, 2025. Now there will be two more gravity assists, both at Earth. The first is on September 27, 2026, and the second is in January 2029. Then it will head out toward Jupiter, arriving in 2031.

This artist’s impression shows the JUICE spacecraft soaring in front of our planetary neighbor Venus. JUICE completed its flyby of Venus on August 31, 2025. Image via ESA.

JUICE mission launched on April 14, 2023

ESA’s JUICE mission launched on April 14, 2023, after a one-day delay due to lightning at ESA’s spaceport in French Guiana. The spacecraft lifted off successfully into cloudy skies, beginning a multi-year mission to Jupiter and its icy moons.

As often happens with missions to the outer solar system, the spacecraft will take a circuitous route to Jupiter, making multiple sweeps past the Earth, moon and Venus. Then, in 2031, it’ll arrive at the giant planet. At that time, it’ll perform 35 flybys of the Galilean moons Ganymede, Callisto and Europa, before going into orbit around the largest moon, Ganymede.

View larger. | This is JUICE’s journey to Jupiter. It will become a reality (fingers crossed) in July 2031, when JUICE is scheduled to arrive at Jupiter. It’s impressive, especially considering the spacecraft will still be soaring around Earth in 2029! Only when it has completed its 2nd flyby of our home planet will JUICE make a quick 2-year hop to Jupiter. There, it’ll complete 35 flybys of the giant planet’s 3 largest moons: Ganymede, Callisto and Europa. Image via ESA.

Jammed antenna

The JUICE mission’s primary antenna jammed soon after launch. But after three weeks of troubleshooting, engineers finally managed to fix the antenna. As the spacecraft traveled through deep space, JUICE mission control tried using thrusters to shake the antenna. Then they tried warming the jammed components in the sun’s rays. Finally, the team fired a mechanical device called an actuator. And that’s what made the antenna break free from its stuck position on May 12, 2023.

This RIME antenna, which stands for Radar for Icy Moons Exploration, will be used to study the structure of Jupiter’s icy moons down to a depth of 5.5 miles (9 km) when it finally reaches the gas giant in July 2031.

JUICE mission goals

ESA said its goals for JUICE are to:

… make detailed observations of the giant gas planet and its three large ocean-bearing moons – Ganymede, Callisto and Europa – with a suite of remote sensing, geophysical and in situ instruments.

And, ESA said, the mission will characterize these moons as both planetary objects and possible habitats.

ESA hopes that a wider study of the Jupiter system can be used as an archetype for gas giant planets and their moons across our Milky Way galaxy.

Why JUICE will study Europa

JUICE will arrive at Jupiter in 2031. One of the moons it will observe is perhaps the most fascinating of the Jovian moons to Earthly scientists: Europa. This moon is thought to have an ocean of liquid water under its icy crust (also made of water ice). And JUICE is designed to look for the sort of chemistry on Europa that is essential to life on Earth, for example organic molecules, or molecules containing carbon that are key to life on Earth.

JUICE also aims to understand the formation of Europa’s surface features and the composition of any non-water-ice material.

Why JUICE will study Ganymede

After a series of flybys of Jupiter and three of its large, icy moons, JUICE will eventually settle into an orbit around the largest moon, Ganymede. JUICE will orbit Ganymede down to 125 miles (200 km) for about three years. It’ll end its mission with an impact on the moon’s surface.

While at Ganymede, JUICE has many science objectives. They include:

• Characterization of the ocean layers and detection of possible subsurface water reservoirs.
• Topographical, geological and compositional mapping of the surface.
• Study of the physical properties of the icy crust.
• Characterization of the internal mass distribution, dynamics and evolution of the interior.
• Investigation of the exosphere.
• Study of Ganymede’s intrinsic magnetic field and its interactions with the Jovian magnetosphere.

Having a better understanding of this wet, cold world will also help us understand possible distant worlds around other suns, scientists say.

JUICE mocktails

Earlier this year, ESA had a little fun with the acronym JUICE, by holding a space juice contest. Check out these beautiful mocktails, and find the recipes here.

Having a little fun with the JUICE mission, these were the winners of ESA’s space juice contest. The mocktails included some made by 7 and 11-year-olds. Image via ESA.

JUICE art, from kids

ESA also invited kids from around the world to create JUICE-inspired artwork. Read more about the contest here. The winning entry – submitted by 8-year-old Yaryna from Ukraine – is going to space! It was painted on the Ariane 5 rocket, which launched JUICE.

Bottom line: The JUICE mission will perform a flyby of Earth on September 27, 2026. The spacecraft is headed toward Jupiter’s icy moons, where it will arrive in 2031.

Here’s what ‘habitable’ means to astronomers

Read more: Icy moons’ puzzling features may be due to salty ice

The post JUICE mission to fly by Earth in late September first appeared on EarthSky.

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This is an artist’s impression of the JUICE mission, which will target Jupiter’s icy moons. In this view, JUICE passes over Ganymede with Jupiter in the background. In order to get there, JUICE must first make 2 more flybys of Earth for gravity assists. Image via ESA (acknowledgement: ATG Medialab).

JUICE mission will fly by Earth in late September

The JUICE mission — which stands for JUpiter Icy Moons Explorer — is on its way to Jupiter, where it will explore its ocean-bearing moons. But its path to Jupiter is not straight. In fact, JUICE will swing by Earth in late September to get a gravity assist. This will be the third of four planned gravity assists to slingshot the spacecraft toward our solar system’s largest planet.

At the moment, ESA puts the date of the flyby as September 27. The countdown for the upcoming Earth flyby according to the ticker at ESA’s website more specifically puts the flyby at around 6:45 a.m. CDT on Monday, September 28, 2026. If this timing has revisions over the next couple weeks, we will update you!

ESA does not currently have a livestream planned for the event. But during the last Earth flyby, it did provide real-time updates.

JUICE launched to space in 2023. Its first gravity assist flyby was the first ever maneuver of its kind. On August 19 and 20, 2024, it swung past both the moon and then Earth. The flyby of the moon and Earth was technically a braking maneuver. It served to line JUICE up for a Venus flyby, where the successful gravity assist sped up the spacecraft, or gave it the juice, if you will. The Venus flyby was on August 31, 2025. Now there will be two more gravity assists, both at Earth. The first is on September 27, 2026, and the second is in January 2029. Then it will head out toward Jupiter, arriving in 2031.

This artist’s impression shows the JUICE spacecraft soaring in front of our planetary neighbor Venus. JUICE completed its flyby of Venus on August 31, 2025. Image via ESA.

JUICE mission launched on April 14, 2023

ESA’s JUICE mission launched on April 14, 2023, after a one-day delay due to lightning at ESA’s spaceport in French Guiana. The spacecraft lifted off successfully into cloudy skies, beginning a multi-year mission to Jupiter and its icy moons.

As often happens with missions to the outer solar system, the spacecraft will take a circuitous route to Jupiter, making multiple sweeps past the Earth, moon and Venus. Then, in 2031, it’ll arrive at the giant planet. At that time, it’ll perform 35 flybys of the Galilean moons Ganymede, Callisto and Europa, before going into orbit around the largest moon, Ganymede.

View larger. | This is JUICE’s journey to Jupiter. It will become a reality (fingers crossed) in July 2031, when JUICE is scheduled to arrive at Jupiter. It’s impressive, especially considering the spacecraft will still be soaring around Earth in 2029! Only when it has completed its 2nd flyby of our home planet will JUICE make a quick 2-year hop to Jupiter. There, it’ll complete 35 flybys of the giant planet’s 3 largest moons: Ganymede, Callisto and Europa. Image via ESA.

Jammed antenna

The JUICE mission’s primary antenna jammed soon after launch. But after three weeks of troubleshooting, engineers finally managed to fix the antenna. As the spacecraft traveled through deep space, JUICE mission control tried using thrusters to shake the antenna. Then they tried warming the jammed components in the sun’s rays. Finally, the team fired a mechanical device called an actuator. And that’s what made the antenna break free from its stuck position on May 12, 2023.

This RIME antenna, which stands for Radar for Icy Moons Exploration, will be used to study the structure of Jupiter’s icy moons down to a depth of 5.5 miles (9 km) when it finally reaches the gas giant in July 2031.

JUICE mission goals

ESA said its goals for JUICE are to:

… make detailed observations of the giant gas planet and its three large ocean-bearing moons – Ganymede, Callisto and Europa – with a suite of remote sensing, geophysical and in situ instruments.

And, ESA said, the mission will characterize these moons as both planetary objects and possible habitats.

ESA hopes that a wider study of the Jupiter system can be used as an archetype for gas giant planets and their moons across our Milky Way galaxy.

Why JUICE will study Europa

JUICE will arrive at Jupiter in 2031. One of the moons it will observe is perhaps the most fascinating of the Jovian moons to Earthly scientists: Europa. This moon is thought to have an ocean of liquid water under its icy crust (also made of water ice). And JUICE is designed to look for the sort of chemistry on Europa that is essential to life on Earth, for example organic molecules, or molecules containing carbon that are key to life on Earth.

JUICE also aims to understand the formation of Europa’s surface features and the composition of any non-water-ice material.

Why JUICE will study Ganymede

After a series of flybys of Jupiter and three of its large, icy moons, JUICE will eventually settle into an orbit around the largest moon, Ganymede. JUICE will orbit Ganymede down to 125 miles (200 km) for about three years. It’ll end its mission with an impact on the moon’s surface.

While at Ganymede, JUICE has many science objectives. They include:

• Characterization of the ocean layers and detection of possible subsurface water reservoirs.
• Topographical, geological and compositional mapping of the surface.
• Study of the physical properties of the icy crust.
• Characterization of the internal mass distribution, dynamics and evolution of the interior.
• Investigation of the exosphere.
• Study of Ganymede’s intrinsic magnetic field and its interactions with the Jovian magnetosphere.

Having a better understanding of this wet, cold world will also help us understand possible distant worlds around other suns, scientists say.

JUICE mocktails

Earlier this year, ESA had a little fun with the acronym JUICE, by holding a space juice contest. Check out these beautiful mocktails, and find the recipes here.

Having a little fun with the JUICE mission, these were the winners of ESA’s space juice contest. The mocktails included some made by 7 and 11-year-olds. Image via ESA.

JUICE art, from kids

ESA also invited kids from around the world to create JUICE-inspired artwork. Read more about the contest here. The winning entry – submitted by 8-year-old Yaryna from Ukraine – is going to space! It was painted on the Ariane 5 rocket, which launched JUICE.

Bottom line: The JUICE mission will perform a flyby of Earth on September 27, 2026. The spacecraft is headed toward Jupiter’s icy moons, where it will arrive in 2031.

Here’s what ‘habitable’ means to astronomers

Read more: Icy moons’ puzzling features may be due to salty ice

The post JUICE mission to fly by Earth in late September first appeared on EarthSky.

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Wildfires near the South Pole burned 90 million years ago

Scientists have found evidence of wildfires burning near the South Pole in Antarctica some 90 million years ago. The new evidence shows that the fires promoted peatlands in wet, swampy forests. Image via James McKay/ Alfred Wegener Institute.

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Wildfires near the South Pole burned 90 million years ago

Today, Antarctica is a vast, frozen landscape. A miles-thick ice sheet covers some 90% of the continent. But some 90 million years ago, during the Late Cretaceous period, scientists say this land was a rainforest where dinosaurs roamed. And on September 7, 2026, researchers with the Alfred Wegener Institute in Bremerhaven, Germany, said wildfires happened here regularly. In fact, they said they have found evidence in sediment cores of the southernmost wildfires ever recorded on Earth.

The researchers published their peer-reviewed paper in the journal Communications Earth and Environment on September 7, 2026.

The South Pole was once a rainforest

Back in 2020, researchers with the Alfred Wegener Institute (AWI) said they found evidence that a rainforest once existed in what is now Antarctica. They extracted a sediment core in an area that is currently in West Antarctica. That sediment core showed clear signs that a lush environment once existed here. Co-author Johann Klages of AWI said:

In a sediment core from the Amundsen Sea in West Antarctica, we found an extremely well-preserved forest soil dating back around 90 million years, containing abundant pollen and spores and a dense network of roots. During the Cretaceous, tectonic conditions meant that this temperate rainforest lay even farther south, just 900 kilometers [560 miles] from the South Pole.

Today, average annual temperatures at this location are around -30 Celsius [-22 F] and everything is covered by an ice sheet several kilometers thick. Our discovery showed that during the warmest period of the Cretaceous, when atmospheric CO2 levels were four to six times higher than today, a relatively warm and humid climate prevailed, even close to the South Pole.

In the new study, the researchers took a closer look at the sediment core and found clear evidence of recurring wildfires.

A closer look at the sediment core

The team found three pieces of evidence in the sediment core from the Late Cretaceous that pointed to recurring fires in this former rainforest.

First, the researchers found minute particles of charcoal. These tiny pieces became more abundant in the younger sediments. Their analysis showed the charcoal was mostly coming from soft conifer wood burning at low temperatures. These fires would be on the surface and not raging across the forest canopy.

Second, the researchers found amber. This amber is fossilized tree resin. In particular, the former tree resin here seems to have flowed over the tree trunks to protect and seal fire-damaged areas.

Third, the researchers found lots of spores of peat moss. Peat moss is a spongy soil made from dead plant matter. It decays slowly over thousands of years. This peat moss was the evidence that there were once raised bogs in Antarctica. The researchers link the formation of the bogs to the recurring fires.

This graph shows the sediment core the team extracted from Western Antarctica. It includes linescan and computed tomography images of the core, with the root network in green. Image via Alfred Wegener Institute/ Jürgen Titschack/ MARUM.

Imagining Antarctica from the past

So now imagine what Antarctica looked like 90 million years ago. First, the land was still partially connected to what is present-day Australia. The average temperature was 53 F (12 C). There were seasons of light and dark below the Antarctic Circle, along with dry periods and monsoon seasons. And sometimes, the monsoon season brought thunderstorms and associated lightning. The lightning struck Earth, igniting what would develop into large-scale fires.

Co-author Ulrich Salzmann of Northumbria University in England said:

90 million years ago, just 900 kilometers [560 miles] from the South Pole, a temperate and very swampy Antarctic rainforest with pronounced dry and monsoon seasons gradually silted up and developed into a peatland dominated by peat mosses.

Wildfires, which became increasingly frequent, clearly played a decisive role in this process. They kept the vegetation open and enabled the development of a peat bog where ground-level smoldering fires then occurred repeatedly, similar to those that have become increasingly common in German peatlands in recent years.

Wildfires near the South Pole and climate

The researchers explain how these boggy peatlands are important in climate change. Peatlands are a carbon sink, or a place where Earth stores its carbon. As co-author Thorsten Bauersachs of RWTH Aachen University said:

Peatlands play a key role in the climate system, both then and now, as highly effective long-term stores of carbon. In a warm climate, wetlands dry up more quickly and fires that prevent forest development occur more frequently. This can promote the formation of peatlands, where carbon-rich plant material accumulates over long periods.

Klages added:

The Late Cretaceous was extremely warm and prone to frequent fires. We were surprised to find evidence in our core of an early Antarctic ecosystem that, in many respects, resembled today’s Arctic raised bogs and also experienced regular fires.

Bottom line: Researchers have found evidence in a sediment core in Antarctica that wildfires near the South Pole were a regular occurrence some 90 million years ago.

Source: Co-evolution of wildfires and early Sphagnum-peatlands near the Cretaceous South Pole

Via Alfred Wegener Institute

Read more: A rainforest in Antarctica during the age of dinosaurs

Read more: Wildfires becoming more frequent in the north: See the maps

The post Wildfires near the South Pole burned 90 million years ago first appeared on EarthSky.

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Scientists have found evidence of wildfires burning near the South Pole in Antarctica some 90 million years ago. The new evidence shows that the fires promoted peatlands in wet, swampy forests. Image via James McKay/ Alfred Wegener Institute.

Love wildlife and the natural world? Get the latest animal stories – as well as space and night sky updates – delivered to your inbox.

Wildfires near the South Pole burned 90 million years ago

Today, Antarctica is a vast, frozen landscape. A miles-thick ice sheet covers some 90% of the continent. But some 90 million years ago, during the Late Cretaceous period, scientists say this land was a rainforest where dinosaurs roamed. And on September 7, 2026, researchers with the Alfred Wegener Institute in Bremerhaven, Germany, said wildfires happened here regularly. In fact, they said they have found evidence in sediment cores of the southernmost wildfires ever recorded on Earth.

The researchers published their peer-reviewed paper in the journal Communications Earth and Environment on September 7, 2026.

The South Pole was once a rainforest

Back in 2020, researchers with the Alfred Wegener Institute (AWI) said they found evidence that a rainforest once existed in what is now Antarctica. They extracted a sediment core in an area that is currently in West Antarctica. That sediment core showed clear signs that a lush environment once existed here. Co-author Johann Klages of AWI said:

In a sediment core from the Amundsen Sea in West Antarctica, we found an extremely well-preserved forest soil dating back around 90 million years, containing abundant pollen and spores and a dense network of roots. During the Cretaceous, tectonic conditions meant that this temperate rainforest lay even farther south, just 900 kilometers [560 miles] from the South Pole.

Today, average annual temperatures at this location are around -30 Celsius [-22 F] and everything is covered by an ice sheet several kilometers thick. Our discovery showed that during the warmest period of the Cretaceous, when atmospheric CO2 levels were four to six times higher than today, a relatively warm and humid climate prevailed, even close to the South Pole.

In the new study, the researchers took a closer look at the sediment core and found clear evidence of recurring wildfires.

A closer look at the sediment core

The team found three pieces of evidence in the sediment core from the Late Cretaceous that pointed to recurring fires in this former rainforest.

First, the researchers found minute particles of charcoal. These tiny pieces became more abundant in the younger sediments. Their analysis showed the charcoal was mostly coming from soft conifer wood burning at low temperatures. These fires would be on the surface and not raging across the forest canopy.

Second, the researchers found amber. This amber is fossilized tree resin. In particular, the former tree resin here seems to have flowed over the tree trunks to protect and seal fire-damaged areas.

Third, the researchers found lots of spores of peat moss. Peat moss is a spongy soil made from dead plant matter. It decays slowly over thousands of years. This peat moss was the evidence that there were once raised bogs in Antarctica. The researchers link the formation of the bogs to the recurring fires.

This graph shows the sediment core the team extracted from Western Antarctica. It includes linescan and computed tomography images of the core, with the root network in green. Image via Alfred Wegener Institute/ Jürgen Titschack/ MARUM.

Imagining Antarctica from the past

So now imagine what Antarctica looked like 90 million years ago. First, the land was still partially connected to what is present-day Australia. The average temperature was 53 F (12 C). There were seasons of light and dark below the Antarctic Circle, along with dry periods and monsoon seasons. And sometimes, the monsoon season brought thunderstorms and associated lightning. The lightning struck Earth, igniting what would develop into large-scale fires.

Co-author Ulrich Salzmann of Northumbria University in England said:

90 million years ago, just 900 kilometers [560 miles] from the South Pole, a temperate and very swampy Antarctic rainforest with pronounced dry and monsoon seasons gradually silted up and developed into a peatland dominated by peat mosses.

Wildfires, which became increasingly frequent, clearly played a decisive role in this process. They kept the vegetation open and enabled the development of a peat bog where ground-level smoldering fires then occurred repeatedly, similar to those that have become increasingly common in German peatlands in recent years.

Wildfires near the South Pole and climate

The researchers explain how these boggy peatlands are important in climate change. Peatlands are a carbon sink, or a place where Earth stores its carbon. As co-author Thorsten Bauersachs of RWTH Aachen University said:

Peatlands play a key role in the climate system, both then and now, as highly effective long-term stores of carbon. In a warm climate, wetlands dry up more quickly and fires that prevent forest development occur more frequently. This can promote the formation of peatlands, where carbon-rich plant material accumulates over long periods.

Klages added:

The Late Cretaceous was extremely warm and prone to frequent fires. We were surprised to find evidence in our core of an early Antarctic ecosystem that, in many respects, resembled today’s Arctic raised bogs and also experienced regular fires.

Bottom line: Researchers have found evidence in a sediment core in Antarctica that wildfires near the South Pole were a regular occurrence some 90 million years ago.

Source: Co-evolution of wildfires and early Sphagnum-peatlands near the Cretaceous South Pole

Via Alfred Wegener Institute

Read more: A rainforest in Antarctica during the age of dinosaurs

Read more: Wildfires becoming more frequent in the north: See the maps

The post Wildfires near the South Pole burned 90 million years ago first appeared on EarthSky.

from EarthSky https://ift.tt/KNJkEVh

Why is Venus so bright in Earth’s sky?

View at EarthSky Community Photos. | Brian Mack captured this image on January 16, 2025, from Big Sur, California. Brian wrote: “Saturn and Venus low over the coast of Central California. The moon is just rising behind me, providing enough lighting for the landscape and ocean to expose in the photograph as well.” Thank you, Brian! Read on to find out why Venus is so bright.

In 2026, Venus emerged in the evening sky in February and will shine brightly in our evening sky through October. It will be at its brightest on September 18.

Why is Venus so bright?

Jupiter is a famously bright planet on our sky, and Mars can be impressively bright, too. But neither Jupiter nor Mars at their brightest can outshine Venus.

Our neighboring world – orbiting one step inward from Earth around the sun – is the third-brightest natural object in the sky, after the sun and the moon. It’s generally shining at around magnitude -4.0.

Venus reached its greatest distance from the evening sun in our sky on August 14-15, 2026. And the planet will be at its dazzling greatest brilliancy in the evening sky on September 18, 2026.

So why is Venus so bright?

Albedo = reflectivity

As the planet next inward from Earth in orbit around the sun, Venus is relatively nearby. But its nearness isn’t the only reason Venus is bright.

Consider that Mars orbits one step outward from Earth. And Mars waxes and wanes in brightness in our sky over about a two-year cycle. It’s only exceptionally bright around the time Earth passes between Mars and the sun, at the same time Mars is closest to the sun. The last time that happened was in 2018. And the next time will be in 2035.

With Venus, something else is going on. Astronomers use the term albedo to describe how bright a planet is in absolute terms. When sunlight strikes a planet, the planet’s surface absorbs some of the light and reflects the rest.

Albedo is a comparison between how much light strikes an object and how much the object reflects. And, as you might have guessed, Venus has the highest albedo of any major planet in our solar system.

Reflectivity makes Venus bright

The albedo of Venus is close to 0.7, meaning it reflects about 70% of the sunlight striking it. For context, the moon – whose surface is dark volcanic rock – reflects only about 10% of the light that hits it. It only appears brighter than Venus to us because it’s close to Earth. It’s only about a light-second away, in contrast to the several light-minutes distance of Venus.

Venus has a high albedo because it’s blanketed by highly reflective clouds. The clouds in the atmosphere of Venus contain droplets of sulfuric acid, as well as acidic crystals suspended in a mixture of gases. Light bounces easily off the smooth surfaces of these droplets and crystals. Sunlight bouncing from these clouds is a big part of why Venus is so bright.

By the way, Venus isn’t the most reflective body in our solar system. That honor goes to Enceladus, a moon of Saturn. The little moon’s icy surface reflects some 90% of the sunlight striking it.

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The phases of Venus – and its locations at inferior and superior conjunction – as viewed from Earth. Adapted from an image by NASA/ Chmee2/ Wikimedia Commons.

When and why is Venus brightest?

Venus is brightest when two factors combine: the phase of its crescent and the overall size of Venus’ disk in our sky. The combination of these factors dictates the amount of Venus’ surface area we see. When the greatest amount of surface area is visible, astronomers call it Venus’ greatest illuminated extent.

Why does it happen? Because Venus orbits the sun inside Earth’s orbit, it sometimes goes between us and the sun. At such times, its lit hemisphere, or day side, is facing away from us. Then it’s difficult to see Venus at all (though experienced astrophotographers sometimes catch it).

Also, around the time it passes between us and the sun – known as inferior conjunction – we see Venus exhibit phases … like a tiny moon (see chart above).

Venus will reach inferior conjunction on October 24, 2026. When Venus is racing toward inferior conjunction and catching up to Earth in our orbit, it’s increasing in size but its phases are shrinking (waning). Then, in October, it will “lap” us in the race of the planets. So, then observers on Earth can watch as the phase of Venus waxes.

As Venus moves away from its inferior conjunction, it’ll decrease in size … but its phase will increase. Smaller disk, but more of that disk visible.

View at EarthSky Community Photos. | Tameem Altameemi captured this image from Dubai and wrote: “This image beautifully captures a fascinating astronomical phenomenon: the similarity between the moon’s and Venus’ phases. Venus, like the moon, goes through phases as seen from Earth. This happens because Venus orbits inside Earth’s orbit, making it an inferior planet. The phase of Venus changes as its position relative to the sun and Earth shifts, like how the moon’s phases change.” Thank you, Tameem!

Venus at greatest brilliancy in September

Venus will pass between us and the sun at 4 UTC on October 24, 2026. Until then, it’ll be rushing to catch up with Earth in our orbit around the sun. Its phase will be decreasing, but its disk size will be increasing.

So there’s a balancing act going on between those two factors; the decreasing phase reduces brightness, but the growing disk size increases brightness. Venus’ greatest brilliancy happens when these two factors combine to give the greatest illuminated surface area. And that happens on September 18, 2026!

Don’t miss Venus blazing after twilight begins around then. Check Stellarium.org for local times.

The view from above

Heliocentric view of solar system, September 2026. Here you can see Venus is racing to catch up with Earth as we orbit around the sun. And Venus will reach its greatest brilliancy on September 18. Chart via Guy Ottewell’s 2026 Astronomical Calendar. Used with permission. Plus Guy Ottewell explains heliocentric charts here.

More photos from our community

View at EarthSky Community Photos. | Gwen Forrester of DeKalb County, Tennessee, captured these images on February 3, 2025. Gwen wrote: “Venus has been shining at its brightest recently, accompanied by the waxing crescent moon, as its own crescent phase wanes. Tonight, they were at roughly equal illumination as viewed from Earth.” Thank you, Gwen!

View at EarthSky Community Photos. | P Govardhana Siddartha of India submitted this composite image of Venus taken over 4 months. Venus was recorded from December 2024 to March 2025 as it raced toward inferior conjunction in March. You can see how the size of Venus increases and the phase decreases. Thank you, P Govardhana!

Bottom line: In 2026, dazzling Venus emerged in the west after sunset in the evening twilight in March. It will be visible in the evening sky through October. It’s the third brightest object in the sky, after the sun and moon. But why is Venus so bright?

Read about Venus at greatest brilliancy

Venus greatest distance from the sun August 14-15, 2026

The post Why is Venus so bright in Earth’s sky? first appeared on EarthSky.

from EarthSky https://ift.tt/ZJOqkw2

View at EarthSky Community Photos. | Brian Mack captured this image on January 16, 2025, from Big Sur, California. Brian wrote: “Saturn and Venus low over the coast of Central California. The moon is just rising behind me, providing enough lighting for the landscape and ocean to expose in the photograph as well.” Thank you, Brian! Read on to find out why Venus is so bright.

In 2026, Venus emerged in the evening sky in February and will shine brightly in our evening sky through October. It will be at its brightest on September 18.

Why is Venus so bright?

Jupiter is a famously bright planet on our sky, and Mars can be impressively bright, too. But neither Jupiter nor Mars at their brightest can outshine Venus.

Our neighboring world – orbiting one step inward from Earth around the sun – is the third-brightest natural object in the sky, after the sun and the moon. It’s generally shining at around magnitude -4.0.

Venus reached its greatest distance from the evening sun in our sky on August 14-15, 2026. And the planet will be at its dazzling greatest brilliancy in the evening sky on September 18, 2026.

So why is Venus so bright?

Albedo = reflectivity

As the planet next inward from Earth in orbit around the sun, Venus is relatively nearby. But its nearness isn’t the only reason Venus is bright.

Consider that Mars orbits one step outward from Earth. And Mars waxes and wanes in brightness in our sky over about a two-year cycle. It’s only exceptionally bright around the time Earth passes between Mars and the sun, at the same time Mars is closest to the sun. The last time that happened was in 2018. And the next time will be in 2035.

With Venus, something else is going on. Astronomers use the term albedo to describe how bright a planet is in absolute terms. When sunlight strikes a planet, the planet’s surface absorbs some of the light and reflects the rest.

Albedo is a comparison between how much light strikes an object and how much the object reflects. And, as you might have guessed, Venus has the highest albedo of any major planet in our solar system.

Reflectivity makes Venus bright

The albedo of Venus is close to 0.7, meaning it reflects about 70% of the sunlight striking it. For context, the moon – whose surface is dark volcanic rock – reflects only about 10% of the light that hits it. It only appears brighter than Venus to us because it’s close to Earth. It’s only about a light-second away, in contrast to the several light-minutes distance of Venus.

Venus has a high albedo because it’s blanketed by highly reflective clouds. The clouds in the atmosphere of Venus contain droplets of sulfuric acid, as well as acidic crystals suspended in a mixture of gases. Light bounces easily off the smooth surfaces of these droplets and crystals. Sunlight bouncing from these clouds is a big part of why Venus is so bright.

By the way, Venus isn’t the most reflective body in our solar system. That honor goes to Enceladus, a moon of Saturn. The little moon’s icy surface reflects some 90% of the sunlight striking it.

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

The phases of Venus – and its locations at inferior and superior conjunction – as viewed from Earth. Adapted from an image by NASA/ Chmee2/ Wikimedia Commons.

When and why is Venus brightest?

Venus is brightest when two factors combine: the phase of its crescent and the overall size of Venus’ disk in our sky. The combination of these factors dictates the amount of Venus’ surface area we see. When the greatest amount of surface area is visible, astronomers call it Venus’ greatest illuminated extent.

Why does it happen? Because Venus orbits the sun inside Earth’s orbit, it sometimes goes between us and the sun. At such times, its lit hemisphere, or day side, is facing away from us. Then it’s difficult to see Venus at all (though experienced astrophotographers sometimes catch it).

Also, around the time it passes between us and the sun – known as inferior conjunction – we see Venus exhibit phases … like a tiny moon (see chart above).

Venus will reach inferior conjunction on October 24, 2026. When Venus is racing toward inferior conjunction and catching up to Earth in our orbit, it’s increasing in size but its phases are shrinking (waning). Then, in October, it will “lap” us in the race of the planets. So, then observers on Earth can watch as the phase of Venus waxes.

As Venus moves away from its inferior conjunction, it’ll decrease in size … but its phase will increase. Smaller disk, but more of that disk visible.

View at EarthSky Community Photos. | Tameem Altameemi captured this image from Dubai and wrote: “This image beautifully captures a fascinating astronomical phenomenon: the similarity between the moon’s and Venus’ phases. Venus, like the moon, goes through phases as seen from Earth. This happens because Venus orbits inside Earth’s orbit, making it an inferior planet. The phase of Venus changes as its position relative to the sun and Earth shifts, like how the moon’s phases change.” Thank you, Tameem!

Venus at greatest brilliancy in September

Venus will pass between us and the sun at 4 UTC on October 24, 2026. Until then, it’ll be rushing to catch up with Earth in our orbit around the sun. Its phase will be decreasing, but its disk size will be increasing.

So there’s a balancing act going on between those two factors; the decreasing phase reduces brightness, but the growing disk size increases brightness. Venus’ greatest brilliancy happens when these two factors combine to give the greatest illuminated surface area. And that happens on September 18, 2026!

Don’t miss Venus blazing after twilight begins around then. Check Stellarium.org for local times.

The view from above

Heliocentric view of solar system, September 2026. Here you can see Venus is racing to catch up with Earth as we orbit around the sun. And Venus will reach its greatest brilliancy on September 18. Chart via Guy Ottewell’s 2026 Astronomical Calendar. Used with permission. Plus Guy Ottewell explains heliocentric charts here.

More photos from our community

View at EarthSky Community Photos. | Gwen Forrester of DeKalb County, Tennessee, captured these images on February 3, 2025. Gwen wrote: “Venus has been shining at its brightest recently, accompanied by the waxing crescent moon, as its own crescent phase wanes. Tonight, they were at roughly equal illumination as viewed from Earth.” Thank you, Gwen!

View at EarthSky Community Photos. | P Govardhana Siddartha of India submitted this composite image of Venus taken over 4 months. Venus was recorded from December 2024 to March 2025 as it raced toward inferior conjunction in March. You can see how the size of Venus increases and the phase decreases. Thank you, P Govardhana!

Bottom line: In 2026, dazzling Venus emerged in the west after sunset in the evening twilight in March. It will be visible in the evening sky through October. It’s the third brightest object in the sky, after the sun and moon. But why is Venus so bright?

Read about Venus at greatest brilliancy

Venus greatest distance from the sun August 14-15, 2026

The post Why is Venus so bright in Earth’s sky? first appeared on EarthSky.

from EarthSky https://ift.tt/ZJOqkw2