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| Asteroids typically come from the main asteroid belt, but a small group of near-Earth objects may actually originate from the Moon, ejected by past impacts. |
In a surprising breakthrough, astronomers have found that the small near-Earth asteroid 2024 PT5, which captivated the world’s attention in 2024, may have been ejected from the Moon’s surface following a massive impact thousands of years ago. The discovery, made possible through observations by several NASA-supported telescopes, sheds light on a rare population of asteroids and could provide new insights into lunar science.
2024 PT5, measuring only about 33 feet (10 meters) across, doesn’t pose any threat to Earth but follows an unusual orbit that closely matches our planet’s, suggesting it may have originated in the Moon’s vicinity. While initially thought to be a typical near-Earth object, researchers have gathered new evidence supporting the idea that it is actually composed of rock that was once part of the Moon’s surface.
The study, published on January 14 in The Astrophysical Journal Letters, details how the asteroid’s composition matches lunar rock samples collected during past missions. “We suspected that this asteroid may have come from the Moon, but the breakthrough came when we found it to be rich in silicate minerals that are typically found in lunar rocks, not those seen in other asteroids,” said lead researcher Teddy Kareta, an astronomer at Lowell Observatory in Arizona.
2024 PT5 was first detected on August 7, 2024, by the ATLAS telescope in South Africa, which is part of a NASA-funded program aimed at identifying potential Earth-threatening objects. Follow-up observations using the Lowell Discovery Telescope and the NASA Infrared Telescope Facility in Hawai’i revealed that the asteroid’s spectral signature closely matched that of lunar rock.
Further analysis of the object’s motion helped rule out the possibility of it being human-made space debris. Objects like old rocket boosters, which also inhabit Earth-like orbits, respond differently to sunlight’s radiation pressure compared to natural asteroids. “2024 PT5’s movement under the influence of solar radiation pressure was too small to be artificial,” said Oscar Fuentes-Muñoz, a co-author of the study. “This confirmed that the object is likely a natural asteroid.”
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| Researchers tracking asteroid 2024 PT5’s motion have found that it never gets captured by Earth’s gravity, instead lingering nearby before continuing its orbit around the Sun. |
2024 PT5 joins a growing list of asteroids thought to have originated from the Moon. In 2016, asteroid 469219 Kamo’oalewa was discovered with a similar Earth-like orbit and is also believed to have been ejected from the lunar surface after a major impact. As astronomical instruments improve, researchers anticipate discovering more such objects, offering exciting new opportunities for studying both asteroids and the Moon.
One of the key aspects of studying these Moon-originating asteroids is their potential to offer insights into the impact cratering processes on the lunar surface. Additionally, these asteroids could provide access to material from deep below the Moon’s surface, which would otherwise be difficult to study.
“This is a fascinating opportunity to explore the Moon from a new perspective,” said Kareta. “We’re studying an asteroid that essentially tells us a story about the Moon’s history.”
With the increasing number of lunar-origin asteroids being discovered, the future of asteroid and lunar science looks particularly bright, offering new pathways to understanding our celestial neighbor.
This research was conducted as part of NASA’s planetary defense program, which is managed by the Planetary Defense Coordination Office at NASA Headquarters.
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