Study suggests small asteroid 2024 PT5 likely originated from the Moon

Study suggests small asteroid 2024 PT5 likely originated from the Moon
by Clarence Oxford
Los Angeles CA (SPX) Jan 23, 2025

The near-Earth object 2024 PT5, a small asteroid discovered in 2024, has been identified as likely originating from the Moon. Scientists believe it was ejected into space thousands of years ago following a significant impact event, offering valuable opportunities to study both asteroid dynamics and lunar geology.

The asteroid, approximately 33 feet (10 meters) wide, was first observed on August 7, 2024, by the University of Hawai'i's Asteroid Terrestrial-impact Last Alert System (ATLAS) telescope in South Africa. Despite its close approach to Earth, the object posed no threat, as it orbited the Sun in a trajectory closely resembling Earth's.

Published in the January 14 edition of the Astrophysical Journal Letters, the study revealed that 2024 PT5's composition closely matches lunar rock samples. "We had a general idea that this asteroid may have come from the Moon, but the smoking gun was when we found out that it was rich in silicate minerals - not the kind that are seen on asteroids but those that have been found in lunar rock samples," explained Teddy Kareta, an astronomer at Lowell Observatory in Arizona who led the study. "It looks like it hasn't been in space for very long, maybe just a few thousand years or so, as there's a lack of space weathering that would have caused its spectrum to redden."

Further analysis involved the Lowell Discovery Telescope and NASA's Infrared Telescope Facility (IRTF) at Mauna Kea, Hawai'i. These observations confirmed that the sunlight reflected off the asteroid's surface did not resemble known asteroid types but instead matched lunar material.

Differentiating Space Rocks from Space Debris

Researchers also studied the object's motion to confirm it was not man-made debris, such as a remnant of past rocket launches. NASA's Center for Near Earth Object Studies (CNEOS) at the Jet Propulsion Laboratory used precise calculations to analyze how 2024 PT5 reacted to solar radiation pressure - the small force exerted by sunlight photons. Unlike hollow rocket parts, which are lighter and more easily influenced by solar radiation, the dense composition of 2024 PT5 showed it was natural rather than artificial.

"Space debris and space rocks move slightly differently in space," said Oscar Fuentes-Munoz, a coauthor of the study and postdoctoral fellow at JPL. "Human-made debris is usually relatively light and gets pushed around by the pressure of sunlight. That 2024 PT5 doesn't move this way indicates it is much denser than space debris."

Implications for Lunar and Asteroid Studies

The discovery doubles the number of known lunar-origin asteroids, joining 469219 Kamo'oalewa, identified in 2016. Both objects provide new avenues for understanding impacts on the Moon and the processes that send lunar material into space. Researchers hope that future discoveries will link specific lunar craters to such asteroids, yielding insights into the Moon's geology and cratering events.

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

Lunar-origin asteroids could also provide unprecedented access to material from deep below the Moon's surface, delivered to Earth's vicinity for study by natural processes. With advancements in telescope sensitivity, researchers anticipate discovering more such objects, broadening our understanding of both the Moon and near-Earth asteroids.

The ATLAS, IRTF, and CNEOS projects receive funding from NASA's Planetary Defense Coordination Office, which oversees efforts to detect and study near-Earth objects.

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