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What’s Up: August 2026 Skywatching Tips from NASA

A solar eclipse, the Perseids, bright Venus after sunset, and a deep partial lunar eclipse highlight August’s skywatching.

Skywatching Highlights

  • Aug. 5: Last Quarter Moon
  • Aug. 12: Total solar eclipse across northern Russia, Greenland, Iceland, northern Spain, and part of Portugal; partial eclipse in parts of the U.S.; New Moon
  • Aug. 12-13: Perseid meteor shower peak under dark skies
  • Aug. 14-16: Venus reaches greatest eastern elongation and shines low in the west after sunset
  • Aug. 27-28: Partial lunar eclipse visible from much of North and South America and parts of Europe and Africa

Transcript

A solar eclipse, one of the year’s best meteor showers, Venus at its brightest in the evening sky, and a lunar eclipse to close out the month.

That’s “What’s Up” for August.

On Aug. 12, a total solar eclipse crosses northern Russia, Greenland, Iceland, and northern Spain, with a small corner of Portugal inside the path of totality.

In parts of the United States, from Alaska to North Carolina, the eclipse is partial. The Moon will take only a small bite out of the Sun, and the amount of coverage will vary with location.

A stylized flat map of the Earth indicating the viewing areas for a solar eclipse, with text on the left reading 'AUGUST 12: SOLAR ECLIPSE'. A semi-transparent dark shadow covers the northern portion of the globe, fanning out from the top edge. Within this shadow, a thin dotted line arcs down from the Arctic, crossing near Greenland and Iceland, passing over the Iberian Peninsula (Spain and Portugal), and ending near the Mediterranean Sea; this line is labeled 'PATH OF TOTALITY'. The broader shaded region surrounding this line is labeled 'PARTIAL ECLIPSE VISIBLE', and it covers northern North America, the Arctic, all of Europe, northern Africa, and northern and western Asia. The unshaded regions covering the rest of the map, including most of the United States, South America, central and southern Africa, and Australia, indicate areas where the eclipse will not be visible.
A map showing viewing areas of the August 2026 total solar eclipse.
NASA/JPL-Caltech

Remember to watch safely. Use certified eclipse glasses or a safe solar viewer any time any part of the Sun is visible. Regular sunglasses are not safe. And never use binoculars, a telescope, or a camera without a solar filter made for the front of the optics.

Later that same night, the Perseid meteor shower will light up the sky, peaking the evening of Aug. 12 into the early morning hours of the 13th. And with a New Moon arriving on the 12th, the skies will be ideally dark.

The Perseids happen every year when Earth passes through a debris stream left behind by Comet Swift-Tuttle. As those tiny bits of comet dust hit our atmosphere at high speed, they burn up as bright streaks of light.

To view this meteor shower, look toward the northeast once it’s fully dark and watch for the constellation Perseus to clear the horizon. This is where the meteors originate, but let your eyes wander, because they can flash across any part of the sky.

For the best view, stay out late as the stars climb higher, find a dark open spot, and give your eyes 30 minutes to adjust.

An illustration of the night sky showing where to look for meteors, with text at the bottom reading 'August 13 looking northeast around 1:30am.' The bottom of the image shows a dark, silhouetted horizon of hills, marked with blue compass directions N (North), NE (Northeast), and E (East). In the center of the sky above NE is a teal burst icon labeled 'RADIANT,' indicating the point from which meteors appear to originate. A bright, white meteor streaks across the dark, starry sky, pointing back toward the radiant. Two other bright celestial objects are labeled: the star 'CAPELLA' is situated low in the sky below the radiant, and the planet 'SATURN' is positioned high up in the upper right corner. Small text in the bottom left corner reads 'Artist's concept.'
This illustration shows where in the night sky to look for the Perseid meteor shower.
NASA/JPL-Caltech

Aug. 14-16, Venus reaches its greatest eastern elongation, which is its widest apparent separation from the Sun during this evening appearance.

Look low in the western sky shortly after sunset for the bright object that will outshine every star around it. Through a telescope after sunset, Venus will look close to half lit, like a tiny lunar phase.

An illustration of the evening sky shortly after sunset, showing the positions of celestial objects. Text at the bottom center reads 'August 14 looking west just after sunset'. The bottom edge features a silhouetted, dark horizon of hills or mountains. Above the horizon, compass directions are indicated in purple: 'SW' (Southwest) on the left, 'W' (West) in the center, and 'NW' (Northwest) on the right. In the center, sitting very low on the horizon, is a faint crescent moon, labeled 'MOON'. Just to the left and slightly above the moon is a bright, white dot labeled 'VENUS'. Higher up and to the left of Venus is a smaller white dot labeled 'SPICA'. Above and to the right of Spica, towards the center of the image, is another labeled star, 'ARCTURUS'. The sky transitions from a deep reddish-purple near the horizon to dark blue at the top, sprinkled with numerous faint stars. In the bottom left corner, small text reads 'Artist's concept.'
This illustration shows where to observe Venus after sunset in August.
NASA/JPL-Caltech

On the night of Aug. 27, continuing into Aug. 28 for some time zones, the Full Moon slips through Earth’s shadow, resulting in a partial lunar eclipse. It will be visible from much of North and South America and parts of Europe and Africa.

A stylized flat map of the Earth indicating the viewing areas for a lunar eclipse, with text at the bottom reading 'AUGUST 27-28: LUNAR ECLIPSE'. Large, semi-transparent dark bands arch across the map to represent visibility zones. The darkest central band, labeled 'FULL ECLIPSE VISIBLE', covers all of North America and South America, as well as the eastern Pacific Ocean and western Atlantic Ocean. Flanking this central region on the left and right are lighter shaded bands labeled 'PARTIAL ECLIPSE VISIBLE'. The western partial eclipse band covers the western Pacific Ocean and New Zealand, while the eastern partial eclipse band covers Europe and Africa. The unshaded outer regions of the map, including most of Asia and Australia, are areas where the eclipse will not be visible.
Viewing areas for the August 2026 lunar eclipse.
NASA/JPL-Caltech

At maximum eclipse, about 93% of the Moon’s diameter will be inside Earth’s dark central shadow, called the umbra. The Moon will not be completely covered, but it can look dramatically darkened, with a rusty, coppery tint along the covered edge.

Unlike a solar eclipse, a lunar eclipse is safe to watch with just your eyes. Binoculars or a small telescope can give you a closer view of Earth’s curved shadow moving across the Moon.

Here are the phases of the Moon for August.

An infographic on a black background titled 'August 2026' showing four primary phases of the Moon arranged in a horizontal row. Each phase features an image of the Moon with text above indicating the phase name and a number below indicating the date in August. From left to right:  'Third Quarter' on the 5th, showing the left half of the Moon illuminated. 'New Moon' on the 12th, showing the Moon's face completely in shadow. 'First Quarter' on the 19th, showing the right half of the Moon illuminated. 'Full Moon' on the 27th, showing the entire face of the Moon illuminated.
NASA/JPL-Caltech

You can stay up to date on all of NASA’s missions exploring the solar system and beyond at science.nasa.gov. I’m Raquel Villanueva from NASA’s Jet Propulsion Laboratory, and that’s What’s Up for this month.

Keep Exploring

Discover More Topics From NASA

The post What’s Up: August 2026 Skywatching Tips from NASA appeared first on NASA Science.

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A solar eclipse, one of the year's best meteor showers, Venus at its brightest in the evening sky, and a partial lunar eclipse to close out the month.On Augu...
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What’s Up: August 2026 Skywatching Tips from NASA

A solar eclipse, the Perseids, bright Venus after sunset, and a deep partial lunar eclipse highlight August’s skywatching.

Skywatching Highlights

  • Aug. 5: Last Quarter Moon
  • Aug. 12: Total solar eclipse across northern Russia, Greenland, Iceland, northern Spain, and part of Portugal; partial eclipse in parts of the U.S.; New Moon
  • Aug. 12-13: Perseid meteor shower peak under dark skies
  • Aug. 14-16: Venus reaches greatest eastern elongation and shines low in the west after sunset
  • Aug. 27-28: Partial lunar eclipse visible from much of North and South America and parts of Europe and Africa

Transcript

A solar eclipse, one of the year’s best meteor showers, Venus at its brightest in the evening sky, and a lunar eclipse to close out the month.

That’s “What’s Up” for August.

On Aug. 12, a total solar eclipse crosses northern Russia, Greenland, Iceland, and northern Spain, with a small corner of Portugal inside the path of totality.

In parts of the United States, from Alaska to North Carolina, the eclipse is partial. The Moon will take only a small bite out of the Sun, and the amount of coverage will vary with location.

A stylized flat map of the Earth indicating the viewing areas for a solar eclipse, with text on the left reading 'AUGUST 12: SOLAR ECLIPSE'. A semi-transparent dark shadow covers the northern portion of the globe, fanning out from the top edge. Within this shadow, a thin dotted line arcs down from the Arctic, crossing near Greenland and Iceland, passing over the Iberian Peninsula (Spain and Portugal), and ending near the Mediterranean Sea; this line is labeled 'PATH OF TOTALITY'. The broader shaded region surrounding this line is labeled 'PARTIAL ECLIPSE VISIBLE', and it covers northern North America, the Arctic, all of Europe, northern Africa, and northern and western Asia. The unshaded regions covering the rest of the map, including most of the United States, South America, central and southern Africa, and Australia, indicate areas where the eclipse will not be visible.
A map showing viewing areas of the August 2026 total solar eclipse.
NASA/JPL-Caltech

Remember to watch safely. Use certified eclipse glasses or a safe solar viewer any time any part of the Sun is visible. Regular sunglasses are not safe. And never use binoculars, a telescope, or a camera without a solar filter made for the front of the optics.

Later that same night, the Perseid meteor shower will light up the sky, peaking the evening of Aug. 12 into the early morning hours of the 13th. And with a New Moon arriving on the 12th, the skies will be ideally dark.

The Perseids happen every year when Earth passes through a debris stream left behind by Comet Swift-Tuttle. As those tiny bits of comet dust hit our atmosphere at high speed, they burn up as bright streaks of light.

To view this meteor shower, look toward the northeast once it’s fully dark and watch for the constellation Perseus to clear the horizon. This is where the meteors originate, but let your eyes wander, because they can flash across any part of the sky.

For the best view, stay out late as the stars climb higher, find a dark open spot, and give your eyes 30 minutes to adjust.

An illustration of the night sky showing where to look for meteors, with text at the bottom reading 'August 13 looking northeast around 1:30am.' The bottom of the image shows a dark, silhouetted horizon of hills, marked with blue compass directions N (North), NE (Northeast), and E (East). In the center of the sky above NE is a teal burst icon labeled 'RADIANT,' indicating the point from which meteors appear to originate. A bright, white meteor streaks across the dark, starry sky, pointing back toward the radiant. Two other bright celestial objects are labeled: the star 'CAPELLA' is situated low in the sky below the radiant, and the planet 'SATURN' is positioned high up in the upper right corner. Small text in the bottom left corner reads 'Artist's concept.'
This illustration shows where in the night sky to look for the Perseid meteor shower.
NASA/JPL-Caltech

Aug. 14-16, Venus reaches its greatest eastern elongation, which is its widest apparent separation from the Sun during this evening appearance.

Look low in the western sky shortly after sunset for the bright object that will outshine every star around it. Through a telescope after sunset, Venus will look close to half lit, like a tiny lunar phase.

An illustration of the evening sky shortly after sunset, showing the positions of celestial objects. Text at the bottom center reads 'August 14 looking west just after sunset'. The bottom edge features a silhouetted, dark horizon of hills or mountains. Above the horizon, compass directions are indicated in purple: 'SW' (Southwest) on the left, 'W' (West) in the center, and 'NW' (Northwest) on the right. In the center, sitting very low on the horizon, is a faint crescent moon, labeled 'MOON'. Just to the left and slightly above the moon is a bright, white dot labeled 'VENUS'. Higher up and to the left of Venus is a smaller white dot labeled 'SPICA'. Above and to the right of Spica, towards the center of the image, is another labeled star, 'ARCTURUS'. The sky transitions from a deep reddish-purple near the horizon to dark blue at the top, sprinkled with numerous faint stars. In the bottom left corner, small text reads 'Artist's concept.'
This illustration shows where to observe Venus after sunset in August.
NASA/JPL-Caltech

On the night of Aug. 27, continuing into Aug. 28 for some time zones, the Full Moon slips through Earth’s shadow, resulting in a partial lunar eclipse. It will be visible from much of North and South America and parts of Europe and Africa.

A stylized flat map of the Earth indicating the viewing areas for a lunar eclipse, with text at the bottom reading 'AUGUST 27-28: LUNAR ECLIPSE'. Large, semi-transparent dark bands arch across the map to represent visibility zones. The darkest central band, labeled 'FULL ECLIPSE VISIBLE', covers all of North America and South America, as well as the eastern Pacific Ocean and western Atlantic Ocean. Flanking this central region on the left and right are lighter shaded bands labeled 'PARTIAL ECLIPSE VISIBLE'. The western partial eclipse band covers the western Pacific Ocean and New Zealand, while the eastern partial eclipse band covers Europe and Africa. The unshaded outer regions of the map, including most of Asia and Australia, are areas where the eclipse will not be visible.
Viewing areas for the August 2026 lunar eclipse.
NASA/JPL-Caltech

At maximum eclipse, about 93% of the Moon’s diameter will be inside Earth’s dark central shadow, called the umbra. The Moon will not be completely covered, but it can look dramatically darkened, with a rusty, coppery tint along the covered edge.

Unlike a solar eclipse, a lunar eclipse is safe to watch with just your eyes. Binoculars or a small telescope can give you a closer view of Earth’s curved shadow moving across the Moon.

Here are the phases of the Moon for August.

An infographic on a black background titled 'August 2026' showing four primary phases of the Moon arranged in a horizontal row. Each phase features an image of the Moon with text above indicating the phase name and a number below indicating the date in August. From left to right:  'Third Quarter' on the 5th, showing the left half of the Moon illuminated. 'New Moon' on the 12th, showing the Moon's face completely in shadow. 'First Quarter' on the 19th, showing the right half of the Moon illuminated. 'Full Moon' on the 27th, showing the entire face of the Moon illuminated.
NASA/JPL-Caltech

You can stay up to date on all of NASA’s missions exploring the solar system and beyond at science.nasa.gov. I’m Raquel Villanueva from NASA’s Jet Propulsion Laboratory, and that’s What’s Up for this month.

Keep Exploring

Discover More Topics From NASA

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July 25, 1920: The birth of Chushiro Hayashi

Born on July 25, 1920, Chushiro Hayashi graduated from the University of Tokyo with a degree in physics in 1942. After World War II service in the navy, he returned to school, finishing his doctorate in 1954 and becoming a professor at Kyoto University in 1957. An innovator, he applied fundamental physics to astronomy andContinue reading "July 25, 1920: The birth of Chushiro Hayashi"

The post July 25, 1920: The birth of Chushiro Hayashi appeared first on Astronomy Magazine.

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NASA’s MAVEN Illuminates New Understanding of Auroras at Mars

This illustration depicts charged particles from a solar storm stripping away charged particles of Mars' atmosphere, one of the processes of Martian atmosphere loss studied by NASA's MAVEN mission, beginning in 2014.
This illustration depicts charged particles from a solar storm stripping away charged particles of Mars’ atmosphere, one of the processes of Martian atmosphere loss studied by NASA’s MAVEN mission.
NASA/GSFC

NASA MAVEN (Mars Atmosphere and Volatile Evolution) mission scientists have uncovered a key puzzle piece in understanding certain types of auroras on Mars, finding that they form in a similar way to Earth-based auroras.
 
Results published Thursday in Nature Communications show the same mechanism that circulates and catapults charged particles into Earth’s atmosphere is happening at Mars on much smaller scales because of differences in the two planets’ magnetic fields.
 
The MAVEN spacecraft, in orbit around Mars, experienced a loss of signal with ground stations on Earth on Dec. 6, 2025. On June 3, NASA declared the mission had concluded after finding the spacecraft to be unrecoverable. However, data from the mission is still being used to inform NASA science and future missions to Mars.
 
When the Sun’s magnetic field lines get close to Earth’s magnetosphere, the large magnetic bubble protecting the planet, they can reconnect and inject energy and mass throughout Earth’s magnetosphere and magnetotail, ultimately firing electrons back into the atmosphere to generate Earth’s auroras. This process, called the Dungey cycle, drives electrical currents, accelerates charged particles that create auroras, and controls the circulation of plasma in Earth’s magnetosphere and ionosphere.
 
This new study shows that a miniature version of the Dungey cycle is happening over Mars’ strong crustal magnetic fields, which gives scientists a better look into the physics of Martian auroras.
 
“We knew that magnetic reconnection was happening at Mars but did not expect it to be like the Dungey cycle,” said Shaosui Xu, lead author of the study and associate research physicist at the Space Sciences Laboratory at the University of California, Berkeley.
 
Mars does not have a global magnetic field like Earth. Earth’s magnetic field is created by our planet’s churning core, while Mars has numerous miniature magnetospheres that arise from intensely magnetized crust scattered around the planet.  These regions were formed around 4 billion years ago when lava cooled in the presence of Mars’ ancient global magnetic field, which has since disappeared due to intense solar wind stripping the planet’s atmosphere.
 
The MAVEN mission has observed highly localized auroras over these crustal fields, similar to Earth’s auroras at the poles, but it wasn’t until now that scientists could fully understand the physics of how they form. The study used several instruments aboard the MAVEN spacecraft to build up a picture of the Dungey-like behavior: the Magnetometer and Solar Wind Electron Analyzer instruments, which were used to determine the magnetic configuration and derive electrical currents, and the STATIC (Suprathermal and Thermal Ion Composition) instrument, which was used to measure plasma flows in the ionosphere.
 
“We really pushed the limit of STATIC to get the data we needed,” said Xu. “It was the final piece to the puzzle in understanding these localized auroras.”
 
The realization that a Dungey-like cycle was happening within these crustal magnetic fields answered the question of how the electrons were being energized to create the auroras. It also shows that a Dungey-like mechanism can happen on both large and small scales, giving more insight into where in the solar system this process could be taking place.
 
“This is a remarkable result that changes how we think of Martian auroras and is another important step toward understanding why Mars and Earth have evolved so differently despite being governed by the same underlying physics.” said Shannon Curry, MAVEN’s principal investigator and a research scientist at the Laboratory for Atmospheric and Space Physics at the University of Colorado Boulder. “I am incredibly proud of our team’s work on this discovery and excited to uncover new insights into the Red Planet and its evolution.”
 
By finding out more about this process, scientists also are gaining a better understanding of how the solar environment interacts with the Red Planet as a whole, which is essential for future robotic and crewed missions.
 
“I remember in graduate school discussing with my advisor how the cycling of crustal magnetic fields could work at Mars,” said Xu. “It’s incredible to be part of the team that found the answer to that question.”
 
The MAVEN mission is part of NASA’s Mars Exploration Program portfolio. The mission’s principal investigator is based at the Laboratory for Atmospheric and Space Physics at the University of Colorado Boulder, which also is responsible for managing science operations and public outreach and communications. NASA’s Goddard Space Flight Center in Greenbelt, Maryland, manages the MAVEN mission. Lockheed Martin Space built the spacecraft and is responsible for mission operations. NASA’s Jet Propulsion Laboratory in Southern California provides navigation and Deep Space Network support.
 
For more information on NASA’s MAVEN mission, visit:
 
https://science.nasa.gov/mission/maven/
 
Karen Fox / Alana Johnson
Headquarters, Washington
240-285-5155 / 202-672-4780
karen.c.fox@nasa.gov / alana.r.johnson@nasa.gov
 
Lonnie Shekhtman
NASA’s Goddard Space Flight Center, Greenbelt, Md.
lonnie.shekhtman@nasa.gov

 

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NASA’s Lucy Reveals Wobbling, Peanut-Shaped Asteroid

Even small asteroids lead complex lives. During its flyby of the asteroid Donaldjohanson last year, NASA’s Lucy spacecraft revealed the asteroid to be a wobbly, peanut-shaped body that has undergone a lot of activity in its relatively short history. Formed as fragments coalesced after a violent collision 155 million years ago, the asteroid was transformed by the small but inexorable force of the Sun’s radiation, all while retaining signs of the brief presence of liquid water in its distant past.

Zooming through the main asteroid belt toward one of the Jupiter Trojan asteroid groups, the Lucy spacecraft collected the first close-up images and other data at Donaldjohanson on April 20, 2025, as it passed 650 miles away from the asteroid. The data revealed that, instead of spinning simply around one axis like most other asteroids and planets, Donaldjohanson has a more complicated two-axis rotation. Scientists also saw Donaldjohanson’s peanut shape and the craters and ridges on its surface.

A timelapse video made from images taken by NASA’s Lucy spacecraft as it approached the asteroid Donaldjohanson on April 20, 2025. The L’LORRI (Lucy Long Range Reconnaissance Imager) instrument, the spacecraft’s high-resolution black-and-white imager, collected these images over two hours as the spacecraft rapidly closed in on the asteroid from an initial separation of more than 58,000 miles (93,000 km), until the spacecraft passed a mere 650 miles (1000 km) from the 5-mile- (8 km-) wide asteroid.
NASA/Goddard/SwRI/JHU-APL

Lucy’s encounter with the asteroid was planned as a dress rehearsal for the spacecraft and mission team before its primary asteroid encounters, which begin with Lucy’s flyby of the Trojan asteroid Eurybates on Aug. 12, 2027. The instruments performed as expected, and, as a bonus, scientists got a rare opportunity to study a previously unexplored asteroid up close and to compare it to two asteroids with similar compositions but different histories: Bennu, the target of NASA’s OSIRIS-REx sample-return mission, and Ryugu, the site of JAXA’s (Japan Aerospace Exploration Agency) Hayabusa2 sample-return mission.

Here’s what Lucy’s science team has learned so far from Lucy’s encounter with Donaldjohanson, as reported on June 18 in the journal Science.

Wobbling rotation

With Earth-based telescopes, observers saw fluctuations in the light Donaldjohanson reflects, regular patterns of peaks and valleys, typical of an elongated object rotating once every 10.5 Earth days. But Lucy’s data revealed another pattern: Donaldjohanson appears to be rotating like a wobbly top. Paper authors reported that the asteroid rotates end-over-end once every 10.5 Earth days, and wobbles back and forth around its long axis once every 26.5 days.

The asteroid Donaldjohanson is shown slowly rotating in a tumbling, non-principal axis motion, with its angular momentum vector and rotation axes indicated. The surface is colored by gravity slope, which measures the angle between the local surface and the direction of gravity. Higher values (warmer colors) indicate steeper terrain relative to the local gravitational pull. Regions with limited stereo image coverage have been masked out where the shape model is less well constrained.
Kel Elkins/NASA’s Science Visualization Studio/DLR

Peanut shape

While the Earth-based observations hinted at Donaldjohanson’s elongated shape, the Lucy flyby revealed a “bilobate” structure: two lobes connected by a neck, like a peanut. These lobes are likely two fragments from an asteroid collision that gently came together afterward by their mutual gravity.

Donaldjohanson likely rotated at least 10 times faster when it formed, having slowed to its current rate in the last 20 to 60 million years, the team estimates. As it slowed, the balance between the centrifugal force pushing things apart and gravity pulling things together changed and loose rocky material slid down slopes creating the worn-down appearance of many craters, as the flyby images showed.

The paper’s authors say that the asteroid’s slowing rotation is likely caused by a subtle consequence of solar heating known as the YORP effect. Each part of the asteroid’s Sun-warmed surface radiates heat away as infrared light, and that radiation imparts a tiny recoil force to the surface. Because the asteroid’s shape isn’t symmetric, this results in a net torque, or twist, that can change the asteroid’s rotation. Thus, YORP can slow asteroid spins down or speed them up, as in the case of Bennu (once every four hours) and Ryugu (once about every seven hours), which both likely used to rotate much slower than they do today.

Fleeting water

As it passed by Donaldjohanson at 30,000 mph, Lucy recorded the signatures of iron-rich clay minerals on the surface. These clays must have formed in the distant past with the help of liquid water. However, the exposure must have been brief, Lucy scientists concluded, because iron in clays tends to be replaced with other elements, such as magnesium, as water lingers.

Indeed, scientists saw magnesium-rich clays at Bennu and Ryugu, which suggested prolonged water exposure, perhaps lasting millions of years, when they were still part of larger asteroids.

This difference in water exposure history, and other characteristics, may mean that the parent bodies of these asteroids formed at different times or in different regions of the solar system before relocating to the main belt.

Compare, contrast

Donaldjohanson is thought to be made from rocky remnants of a larger, carbon- and water-rich asteroid that collided with another object in the main asteroid belt. Bennu and Ryugu are thought to have formed in the same way and in the same region.

But Donaldjohanson is different. At 155 million years old, it is much younger than Bennu and Ryugu, which formed 1 to 2 billion years ago. Donaldjohanson also has remained in the asteroid belt since birth, while its wandering cousins migrated into orbits around the Sun that bring them close to Earth’s orbit about once a year (which made them perfect close targets for sample return missions).

Black background graphic with a large white title at top. Upper left shows a gray, pea-nut-shaped, rock-like object. Upper right shows a rectangular inset image of a dark textured rock fragment. Near the center are a mission patch logo and a small globe with Antarctica highlighted. Lower half contains two side-by-side charts with axes, tick marks, and blue and green plotted lines with scattered blue data points. Additional white, blue, and green labels appear throughout the graphic.
During its April 20, 2025, encounter with the main-belt asteroid Donaldjohanson, NASA’s Lucy spacecraft discovered evidence for iron-rich clays on the surface using its infrared spectrometer. These clays, which are similar to those found in carbon-rich meteorites such as QUE 97990, indicate that water was briefly present in the asteroid during the distant past.
NASA/Goddard/SwRI/Dan Gallagher

“It’s helpful for scientists to compare Donaldjohanson with asteroids like Bennu and Ryugu, which are seemingly similar asteroids, because every subtle difference is another clue to our origin story,” said Simone Marchi, Lucy deputy principal investigator and lead author of the study at the Boulder, Colorado, office of the Southwest Research Institute.

“Once we start learning more about the Trojans, a completely different population of space rocks with very different histories, our understanding of solar system formation is destined to be challenged,” said Marchi.

Named after a fossilized skeleton of a human ancestor discovered in Ethiopia in 1974, NASA’s Lucy will be the first mission to explore Jupiter’s Trojan asteroids, a population of well-preserved space rocks that formed early in our solar system’s history and could help scientists understand how the planets formed and moved around before settling in their current configuration.

Download story graphics from NASA’s Scientific Visualization Studio.

About Lucy:

Lucy’s principal investigator is based out of the Boulder, Colorado, branch of Southwest Research Institute, headquartered in San Antonio. NASA’s Goddard Space Flight Center in Greenbelt, Maryland, provides overall mission management, systems engineering, and safety and mission assurance. Lockheed Martin Space in Littleton, Colorado, built the spacecraft. Lucy is the 13th mission in NASA’s Discovery Program. NASA’s Marshall Space Flight Center in Huntsville, Alabama, manages the Discovery Program for the agency’s Science Mission Directorate in Washington.

For more information on NASA’s Lucy mission, visit:

By Lonnie Shekhtman

NASA’s Goddard Space Flight Center, Greenbelt, Md.

and

Katherine Kretke

Southwest Research Institute, Boulder, Colo.

Media Contacts:

Karen Fox / Molly Wasser

Headquarters, Washington
240-285-5155 / 240-419-1732
karen.c.fox@nasa.gov / molly.l.wasser@nasa.gov

Sarah Frazier

NASA’s Goddard Space Flight Center, Greenbelt, Md.
202-853-7191
sarah.frazier@nasa.gov

Simplified Summary

Zooming through the main asteroid belt toward one of the Jupiter Trojan asteroid groups, the Lucy spacecraft collected the first close-up images and other data at Donaldjohanson on April 20, 2025, as it passed 650 miles away from the asteroid. The data revealed that, instead of spinning simply around one axis like most other asteroids and planets, Donaldjohanson has a more complicated two-axis rotation. Scientists also saw Donaldjohanson’s peanut shape and the craters and ridges on its surface.

The post NASA’s Lucy Reveals Wobbling, Peanut-Shaped Asteroid appeared first on NASA Science.

  •  

NASA’s Lucy Reveals Wobbling, Peanut-Shaped Asteroid

Even small asteroids lead complex lives. During its flyby of the asteroid Donaldjohanson last year, NASA’s Lucy spacecraft revealed the asteroid to be a wobbly, peanut-shaped body that has undergone a lot of activity in its relatively short history. Formed as fragments coalesced after a violent collision 155 million years ago, the asteroid was transformed by the small but inexorable force of the Sun’s radiation, all while retaining signs of the brief presence of liquid water in its distant past.

Zooming through the main asteroid belt toward one of the Jupiter Trojan asteroid groups, the Lucy spacecraft collected the first close-up images and other data at Donaldjohanson on April 20, 2025, as it passed 650 miles away from the asteroid. The data revealed that, instead of spinning simply around one axis like most other asteroids and planets, Donaldjohanson has a more complicated two-axis rotation. Scientists also saw Donaldjohanson’s peanut shape and the craters and ridges on its surface.

A timelapse video made from images taken by NASA’s Lucy spacecraft as it approached the asteroid Donaldjohanson on April 20, 2025. The L’LORRI (Lucy Long Range Reconnaissance Imager) instrument, the spacecraft’s high-resolution black-and-white imager, collected these images over two hours as the spacecraft rapidly closed in on the asteroid from an initial separation of more than 58,000 miles (93,000 km), until the spacecraft passed a mere 650 miles (1000 km) from the 5-mile- (8 km-) wide asteroid.
NASA/Goddard/SwRI/JHU-APL

Lucy’s encounter with the asteroid was planned as a dress rehearsal for the spacecraft and mission team before its primary asteroid encounters, which begin with Lucy’s flyby of the Trojan asteroid Eurybates on Aug. 12, 2027. The instruments performed as expected, and, as a bonus, scientists got a rare opportunity to study a previously unexplored asteroid up close and to compare it to two asteroids with similar compositions but different histories: Bennu, the target of NASA’s OSIRIS-REx sample-return mission, and Ryugu, the site of JAXA’s (Japan Aerospace Exploration Agency) Hayabusa2 sample-return mission.

Here’s what Lucy’s science team has learned so far from Lucy’s encounter with Donaldjohanson, as reported on June 18 in the journal Science.

Wobbling rotation

With Earth-based telescopes, observers saw fluctuations in the light Donaldjohanson reflects, regular patterns of peaks and valleys, typical of an elongated object rotating once every 10.5 Earth days. But Lucy’s data revealed another pattern: Donaldjohanson appears to be rotating like a wobbly top. Paper authors reported that the asteroid rotates end-over-end once every 10.5 Earth days, and wobbles back and forth around its long axis once every 26.5 days.

The asteroid Donaldjohanson is shown slowly rotating in a tumbling, non-principal axis motion, with its angular momentum vector and rotation axes indicated. The surface is colored by gravity slope, which measures the angle between the local surface and the direction of gravity. Higher values (warmer colors) indicate steeper terrain relative to the local gravitational pull. Regions with limited stereo image coverage have been masked out where the shape model is less well constrained.
Kel Elkins/NASA’s Science Visualization Studio/DLR

Peanut shape

While the Earth-based observations hinted at Donaldjohanson’s elongated shape, the Lucy flyby revealed a “bilobate” structure: two lobes connected by a neck, like a peanut. These lobes are likely two fragments from an asteroid collision that gently came together afterward by their mutual gravity.

Donaldjohanson likely rotated at least 10 times faster when it formed, having slowed to its current rate in the last 20 to 60 million years, the team estimates. As it slowed, the balance between the centrifugal force pushing things apart and gravity pulling things together changed and loose rocky material slid down slopes creating the worn-down appearance of many craters, as the flyby images showed.

The paper’s authors say that the asteroid’s slowing rotation is likely caused by a subtle consequence of solar heating known as the YORP effect. Each part of the asteroid’s Sun-warmed surface radiates heat away as infrared light, and that radiation imparts a tiny recoil force to the surface. Because the asteroid’s shape isn’t symmetric, this results in a net torque, or twist, that can change the asteroid’s rotation. Thus, YORP can slow asteroid spins down or speed them up, as in the case of Bennu (once every four hours) and Ryugu (once about every seven hours), which both likely used to rotate much slower than they do today.

Fleeting water

As it passed by Donaldjohanson at 30,000 mph, Lucy recorded the signatures of iron-rich clay minerals on the surface. These clays must have formed in the distant past with the help of liquid water. However, the exposure must have been brief, Lucy scientists concluded, because iron in clays tends to be replaced with other elements, such as magnesium, as water lingers.

Indeed, scientists saw magnesium-rich clays at Bennu and Ryugu, which suggested prolonged water exposure, perhaps lasting millions of years, when they were still part of larger asteroids.

This difference in water exposure history, and other characteristics, may mean that the parent bodies of these asteroids formed at different times or in different regions of the solar system before relocating to the main belt.

Compare, contrast

Donaldjohanson is thought to be made from rocky remnants of a larger, carbon- and water-rich asteroid that collided with another object in the main asteroid belt. Bennu and Ryugu are thought to have formed in the same way and in the same region.

But Donaldjohanson is different. At 155 million years old, it is much younger than Bennu and Ryugu, which formed 1 to 2 billion years ago. Donaldjohanson also has remained in the asteroid belt since birth, while its wandering cousins migrated into orbits around the Sun that bring them close to Earth’s orbit about once a year (which made them perfect close targets for sample return missions).

Black background graphic with a large white title at top. Upper left shows a gray, pea-nut-shaped, rock-like object. Upper right shows a rectangular inset image of a dark textured rock fragment. Near the center are a mission patch logo and a small globe with Antarctica highlighted. Lower half contains two side-by-side charts with axes, tick marks, and blue and green plotted lines with scattered blue data points. Additional white, blue, and green labels appear throughout the graphic.
During its April 20, 2025, encounter with the main-belt asteroid Donaldjohanson, NASA’s Lucy spacecraft discovered evidence for iron-rich clays on the surface using its infrared spectrometer. These clays, which are similar to those found in carbon-rich meteorites such as QUE 97990, indicate that water was briefly present in the asteroid during the distant past.
NASA/Goddard/SwRI/Dan Gallagher

“It’s helpful for scientists to compare Donaldjohanson with asteroids like Bennu and Ryugu, which are seemingly similar asteroids, because every subtle difference is another clue to our origin story,” said Simone Marchi, Lucy deputy principal investigator and lead author of the study at the Boulder, Colorado, office of the Southwest Research Institute.

“Once we start learning more about the Trojans, a completely different population of space rocks with very different histories, our understanding of solar system formation is destined to be challenged,” said Marchi.

Named after a fossilized skeleton of a human ancestor discovered in Ethiopia in 1974, NASA’s Lucy will be the first mission to explore Jupiter’s Trojan asteroids, a population of well-preserved space rocks that formed early in our solar system’s history and could help scientists understand how the planets formed and moved around before settling in their current configuration.

Download story graphics from NASA’s Scientific Visualization Studio.

About Lucy:

Lucy’s principal investigator is based out of the Boulder, Colorado, branch of Southwest Research Institute, headquartered in San Antonio. NASA’s Goddard Space Flight Center in Greenbelt, Maryland, provides overall mission management, systems engineering, and safety and mission assurance. Lockheed Martin Space in Littleton, Colorado, built the spacecraft. Lucy is the 13th mission in NASA’s Discovery Program. NASA’s Marshall Space Flight Center in Huntsville, Alabama, manages the Discovery Program for the agency’s Science Mission Directorate in Washington.

For more information on NASA’s Lucy mission, visit:

By Lonnie Shekhtman

NASA’s Goddard Space Flight Center, Greenbelt, Md.

and

Katherine Kretke

Southwest Research Institute, Boulder, Colo.

Media Contacts:

Karen Fox / Molly Wasser

Headquarters, Washington
240-285-5155 / 240-419-1732
karen.c.fox@nasa.gov / molly.l.wasser@nasa.gov

Sarah Frazier

NASA’s Goddard Space Flight Center, Greenbelt, Md.
202-853-7191
sarah.frazier@nasa.gov

Simplified Summary

Zooming through the main asteroid belt toward one of the Jupiter Trojan asteroid groups, the Lucy spacecraft collected the first close-up images and other data at Donaldjohanson on April 20, 2025, as it passed 650 miles away from the asteroid. The data revealed that, instead of spinning simply around one axis like most other asteroids and planets, Donaldjohanson has a more complicated two-axis rotation. Scientists also saw Donaldjohanson’s peanut shape and the craters and ridges on its surface.

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