Astro Blog

By Robin George Andrews , The New York Times.  Excerpt: New research suggests that Theia, the object whose collision with Earth is theorized to have caused the formation of the moon, came from closer to the sun. ...A study published Thursday in the journal  Science  ...looking at chemical clues hidden in Earth’s rocks, meteorites and moon matter, scientists have found ghostly remnants of Theia. And they show that Theia and the early Earth were built from the same construction materials....  Full article at https://www.nytimes.com/2025/11/20/science/moon-collision-earth-theia.html . 

By Paul Voosen , Science.  Excerpt: ...the Moon formed some 65 million years after the start of the Solar System—and only tens of millions of years after Earth. The findings promise to resolve decades of debate about the Moon’s age, says Thorsten Kleine, a cosmochemist at the Max Planck Institute for Solar System Research who  presented new work  here at the Lunar and Planetary Science Conference (LPSC). Several strands of research are converging on a new and older age for the Moon, he says: “It’s about 4.5 billion years.”...  Full article at https://www.science.org/content/article/impact-formed-moon-struck-practically-newborn-earth .

By Zexian Cui et al, Science.  Summary: Between 1969 and 1976, the Apollo and Luna missions collected samples from the ...near side of the Moon—the one that always faces Earth. Observations from lunar orbit have shown that the far side has very different geology from the near side, for unknown reasons. ...In June 2024, the Chang’e-6 spacecraft landed within an impact basin on the far side of the Moon, collected samples, then brought them back to Earth. In a new Science paper , researchers present early results from analyses of a Chang’e-6 sample, which contains volcanic basalt...the volcanic eruption occurred 2.8 billion years ago....  Paper at https://www.science.org/doi/10.1126/science.adt1093 . 

By Nathaniel Scharping , agu.  Excerpt: In 2009, NASA intentionally crashed a spacecraft into the Moon ...The  Lunar Crater Observation and Sensing Satellite  (LCROSS) was designed to search for frozen lunar water and other volatiles in the lunar regolith by knocking them off the Moon. ...The LCROSS impact kicked up a cloud of regolith containing plenty of water (5.6% by mass), ...But it did so in a permanently shadowed area of the Moon, leaving scientists unable to directly observe the crater after its formation. ... Fassett et al.  ...researchers ...see the LCROSS crater directly.... The LCROSS impact crater is about 22 meters across, the researchers report, slightly smaller than the LCROSS team  originally estimated . ...the volatiles themselves are young and came from outside the Moon—perhaps from comets, asteroids, or the solar wind—rather than from volcanic eruptions early in the Moon’s history. ...These data could be complemented by future missions, such ...

By Yuri Amelin  and  Qing-Zhu Yin , Science.  Excerpt: Analyses of rocks and soils delivered by the Apollo and Luna missions have established that the Moon is ancient, dry, and depleted of volatile elements. Studies also have indicated that early in its history, the Moon was covered with molten rock. This magma ocean eventually cooled and produced a compositionally diverse surface crust ( 1 ). How long the Moon produced magma has been an open question. On page 1077 of this issue, Wang  et al . ( 2 ) report that volcanism on the Moon occurred as recently as 120 million years ago (Ma). This implies that the Moon may still be able to produce magma. ...Determining the time range of lunar volcanism can be expanded by studying volcanic glass beads produced by lava fountains (eruptions) and preserved in lunar regolith (surface rock and debris) ( 11 ). These beads, despite sizes of only a few tens of micrometers, can be dated with argon ( 40 Ar/ 39 Ar) and uranium-...

By Rachel Fritts , Eos/AGU.  Excerpt: The giant impact that formed the Moon may also have led to extrastrong mantle plumes that enabled the first subduction event, kick-starting Earth’s unique system of sliding plates. In a new study,  Yuan et al.  find evidence tracing the first subduction event to the same impact that created our Moon. ...Yuan’s team explored postimpact mantle convection using both 2D and 3D thermomechanical modeling. They found that the increase in temperature at the core-mantle boundary after the giant impact could have led, over time, to strong  mantle plumes —phenomena still seen today that can sometimes lead to volcanic activity far from plate boundaries....  Full article at https://eos.org/research-spotlights/earths-subduction-may-have-been-triggered-by-the-same-event-that-formed-the-moon . 

By DANIEL CLERY , Science.  Excerpt: Astronomers suspect an unusual near-Earth rocky object is not a typical escapee from the Solar System’s asteroid belt, but is instead a chunk of the Moon blasted into space eons ago by a spectacular impact. Now, a team of researchers has modeled what sort of lunar impact could have ejected such a gobbet of Moon and deposit it in a stable, nearby orbit. Surprisingly, only one strong candidate emerged: the asteroid strike that created the famous Giordano Bruno crater, the youngest large crater on the Moon, the  group reports today  in Nature Astronomy. ...The odd asteroid, known as 469219 Kamo‘oalewa, was discovered in 2016 ...measures between 40 and 100 meters across and rotates particularly fast—once every 28 minutes. It follows an elliptical orbit around the Sun that moves in sync with Earth, giving the impression that the asteroid orbits Earth, even though it is outside the planet’s gravitational influence. The asteroid’s curiou...

https://eos.org/articles/the-moon-is-even-older-than-scientists-thought By Matt Hrodey , Eos/AGU.  Excerpt: Thanks to one of the slowest-ticking clocks in the universe, scientists have determined the Moon is about 40 million years older than previously thought. That means the Earth was a young 100 million years old when an object about the size of Mars slammed into it, slinging magma out into Earth’s orbit. ...As the Moon’s mantle cooled, it formed tiny zircon crystals, ...sometimes contain other elements, such as uranium ...can be used to date when the crystal originally formed, going back billions of years, if necessary. ...the researchers obtained lunar dust collected by Apollo 17 in 1972 and analyzed the tiny zircon crystals and uranium contained inside. ...Radioactive isotopes of uranium (such as Uranium-238) contain unstable combinations of protons and neutrons in their nuclei and will eventually break down into lead... Scientists determined the age of the Moon by counting th...

https://eos.org/articles/a-day-in-the-life-used-to-be-17-hours By Emily Shepherd , Eos/AGU.  Excerpt: The Moon was a lot closer to Earth 2.46 billion years ago, and the shorter distance contributed to shorter days. ...new research has calculated the distance of the Moon 2.46 billion years ago, nearly doubling the age of the previous estimate. Because the length of the day is tightly, tidally tied to the location of the Moon, the research has also calculated how long a day lasted at the time: 17 hours. ...To determine the distance of the Moon, scientists studied rhythmic patterns in Earth’s orbit and axis called  Milankovitch cycles , explained  Margriet Lantink , a geologist at the University of Wisconsin–Madison and lead author of the  new study in the  Proceedings of the National Academy of Sciences of the United States of America ....

https://eos.org/articles/to-make-a-big-moon-start-with-a-small-planet By Kimberly M. S. Cartier , Eos/AGU.  Excerpt: In a contest of which planet in the solar system has the most relatively massive moon, Earth takes the prize. The Moon is roughly 1% of Earth’s mass, whereas the moons of all the remaining moon-bearing planets—that’s all of them save for Mercury and Venus—are less than one ten thousandth their planets’ masses. ...“We think that a giant impact is a very efficient way to form fractionally large moons,” said  Miki Nakajima , a planetary scientist at the University of Rochester in New York. Large collisions are thought to be a common occurrence in the chaos of a still-forming solar system, but if all giant impacts formed fractionally large moons, our solar system would be rife with them. ...Using computer simulations, Nakajima and her colleagues explored what happens when rocky or icy would-be planets of various sizes collide. The researchers found that after such a...

https://www.sciencemag.org/news/2021/03/remains-impact-created-moon-may-lie-deep-within-earth Source:    By  Paul Voosen .  Excerpt: Scientists have long agreed that the Moon formed when a protoplanet, called Theia, struck Earth in its infancy some 4.5 billion years ago. Now, a team of scientists has a provocative new proposal: Theia’s remains can be found in two continent-size layers of rock buried deep in Earth’s mantle. For decades, seismologists have puzzled over these two blobs, which sit below West Africa and the Pacific Ocean and straddle the core like a pair of headphones. Up to 1000 kilometers tall and several times that wide, “they are the largest thing in the Earth’s mantle,” says Qian Yuan, a Ph.D. student in geodynamics at Arizona State University (ASU), Tempe. Seismic waves from earthquakes abruptly slow down when they pass through the layers, which suggests they are denser and chemically different from the surrounding mantle rock. ...Evidence from Ic...

https://www.sciencemag.org/news/2020/12/china-lands-its-moon-rocks-inner-mongolia Source:  By   Paul Voosen , Science Magazine.  Excerpt: China’s Chang’e-5 mission made a triumphant return around 1 p.m. EST today, landing in the middle of the night on the dark frozen plains of Inner Mongolia, Chinese   state media reported . The capsule’s return marks the first time China has collected rocks from the Moon—and the first time any nation has accomplished the feat since 1976. The 3-week-long mission   was the most complicated   in the history of China’s robotic space exploration program, involving a lunar landing, furious scooping and drilling of up to 2 kilograms of grit, and then an ascent and rendezvous with an orbiter, which carried the samples back to Earth. The China National Space Administration, typically secretive with its missions, showed growing confidence in its space program, with live broadcasts of the rocket launch and return of its sample caps...

https://eos.org/research-spotlights/moon-may-hold-billions-of-tons-of-subterranean-ice-at-its-poles Source:  By Jerald Pinson, Eos/AGU.  Excerpt: New research indicates that if even a moderate amount of the water delivered by asteroids to the Moon was sequestered, the lunar poles would contain gigaton deposits (1 billion metric tons) of ice in sheltered craters and beneath its surface. ...“We looked at the entire time history of ice deposition on the Moon,” said   Kevin Cannon , a planetary scientist at the Colorado School of Mines in Golden and lead author of the   new study   in the AGU journal Geophysical Research Letters. Cannon and his team used conservative estimates for the amount of water that asteroids were likely to contain upon impact with the Moon and how much of it was likely to be retained once the dust had settled. ...“If the very oldest regions have been stable and accumulating ice for billions of years, then some could have very substantial de...

https://www.nasa.gov/image-feature/ames/planetary-impact-simulation s Source:    By Frank Tavares, NASA.  Excerpt: The histories of planets across our solar system and beyond are filled with collisions and transformations. New research is helping scientists understand how colossal impacts, like the one with Earth thought to have formed the Moon, are impacting the atmospheres of rocky planets.In the animation above, a Mars-like mass grazes an Earth-like mass, replicating the traditional theory for the impact that formed the Moon. Some atmosphere is lost, accompanied by a shockwave....    

https://www.nytimes.com/2020/08/15/science/moon-lasers-dust.html Source:    By Katherine Kornei, The New York Times.  Excerpt: The moon is drifting away. Every year, it gets about an inch and a half farther from us. Hundreds of millions of years from now, our companion in the sky will be distant enough that there will be no more total solar eclipses. For decades, scientists have measured the moon’s retreat by firing a laser at light-reflecting panels, known as retroreflectors, that were left on the lunar surface, and then timing the light’s round trip. But the moon’s five retroreflectors are old, and they’re now much less efficient at flinging back light. To determine whether a layer of moon dust might be the culprit, researchers devised an audacious plan: They bounced laser light off a much smaller but newer retroreflector mounted aboard a NASA spacecraft that was skimming over the moon’s surface at thousands of miles per hour. And it worked. These results were publish...

https://eos.org/articles/the-quaking-shrinking-moon Source:   By Rachel Crowell, Eos/AGU. Excerpt: New evidence suggests that the Moon may still be tectonically active. Between 1969 and 1977, lunar seismometers at four Apollo landing sites recorded 28 shallow moonquakes. However, the data transmitted by those seismometers were low resolution by current standards, making it difficult to locate the moonquakes’ epicenters. ...The orbital timing of these quakes was also significant. Seven of them occurred at near apogee, when compression of the Moon is near its maximum and fault slip events are likely to occur, according to the study. ...Although these results illustrate an exciting discovery, they also show the need for putting modern seismometers on the Moon....  

https://www.nytimes.com/2019/05/01/science/moon-earth-collision.html Source:   By Robin George Andrews, The New York Times. Excerpt: ...A study [ https://www.nature.com/articles/s41561-019-0354-2 ] published on Monday in Nature Geoscience suggests that the moon was forged from the fires of an ocean of magma sloshing over baby Earth’s surface. If correct, this model may solve a longstanding paradox. Lunar meteorites and samples collected during the Apollo missions show that the moon and Earth have remarkably similar geochemical fingerprints. Scientists suspect that this was likely the result of a giant impactor the size of Mars, known as Theia, that slammed into a young Earth and sent into orbit a spiral of material that coalesced into the moon. Countless computer simulations show that this is possible, but there’s a problem. Such an impact on a relatively solid Earth would have created a moon made mostly out of Theia, not Earth (at least in simulations resulting in the Earth-mo...

https://eos.org/research-spotlights/how-the-moon-got-its-concentric-rings Source:   By Emily Underwood, Eos/AGU. Excerpt: The Moon is pockmarked with impact craters from collisions with meteorites and asteroids, some as big as 1,000 kilometers in diameter. These massive impact craters contain three or more concentric rings, a mysterious feature that has long intrigued scientists interested in how Earth’s early surface and those of other planets evolved. Now a new study, in which scientists simulated an asteroid bigger than New York City slamming into a Moon-like object, explores how such rings form. ...To get a fresh perspective on this complex crater structure, Johnson et al. took advantage of data from NASA’s Gravity Recovery and Interior Laboratory (GRAIL) mission: two washing machine–sized spacecraft that orbit the Moon and produce a high-resolution map of its gravitational field. Using this new, 10-kilometer-scale data, the authors were able to build a high-resolution comp...

https://eos.org/articles/apollo-may-have-found-an-earth-meteorite-on-the-moon Source:   By Kimberly M. S. Cartier, Eos/AGU. Excerpt: The meteorite may have been blasted off of Earth during an impact, mixed with lunar rocks, and brought back to Earth 4 billion years later by astronauts. A rock sample brought back by Apollo 14 may contain the first evidence of Earth material on the Moon. New analysis of zircon grains in one lunar sample suggests that the zircon formed under conditions typical in Earth’s crust and not on the Moon. ...“I expect there could be a bit of controversy because this is the first of its kind,” [Jeremy] Bellucci said. “Hopefully,” he said, “it inspires a search for more Earth materials and further analyses on these samples.”...

https://eos.org/research-spotlights/the-case-of-the-missing-lunar-heat-flow-data-is-finally-solved Source:   By Sarah Stanley, Eos/AGU. Excerpt: Decades-old data analyzed for the first time suggest that astronauts’ disturbance of the Moon surface increased solar heat intake, warming the ground below. During the Apollo 15 and 17 missions, astronauts installed four temperature-sensing probes in shallow, 1.0- to 2.4-meter-deep holes drilled into the Moon. They aimed to measure how much of the Moon’s heat was lost to space, which could provide insights into the origin and the differentiation history of the Moon. The Apollo Heat Flow Experiment ran from 1971 to 1977.  ...In 2011, the researchers reported that they had found about 10% of the missing tapes at the Washington National Records Center in Maryland. ...They found that from 1974 until the Heat Flow Experiment concluded in 1977, the lunar subsurface warmed up, with greater warming occurring at shallower depths. This cont...