Asteroid Encounter: New Insights Reveal Earth’s Tiny Visitor May Be a Piece of the Moon!

The diminutive near-Earth body 2024 PT5 attracted global interest last year after a NASA-sponsored telescope identified it as lingering near to, but not orbiting, our planet for a number of months. The asteroid, which measures approximately 33 feet (10 meters) across, does not present a threat to Earth; however, its trajectory around the Sun closely resembles Earth’s path, suggesting it may have originated from the vicinity.

In a research study released on Jan. 14 in the Astrophysical Journal Letters, scientists have gathered additional evidence supporting the local origin of 2024 PT5: It seems to consist of rock material that was dislodged from the Moon’s surface and cast into space following a significant impact.

“We had a general suspicion that this asteroid might have originated from the Moon, but the crucial evidence emerged when we discovered that it was abundant in silicate minerals — not the types typically found on asteroids, but those identified in lunar rock specimens,” stated Teddy Kareta, an astronomer at Lowell Observatory in Arizona, who spearheaded the investigation. “It appears that it hasn’t been in outer space for an extended period, possibly just a few thousand years, given the absence of space weathering that would have altered its spectrum to appear redder.”

The asteroid was initially observed on Aug. 7, 2024, by the NASA-supported Sutherland telescope in South Africa as part of the University of Hawai’i’s Asteroid Terrestrial-impact Last Alert System (ATLAS). Kareta’s team subsequently utilized observations from the Lowell Discovery Telescope and the NASA Infrared Telescope Facility (IRTF) located at the Mauna Kea Observatory in Hawai’i to demonstrate that the spectrum of sunlight reflected from the small object’s surface did not correspond to that of any documented asteroid category; instead, the light reflected appeared to resemble lunar rock more closely.

Not (Old) Rocket Science

A further clue was obtained from monitoring the object’s movement. Alongside asteroids, debris from the Space Age, including old rockets from historic launches, can also occupy orbits akin to Earth’s.

The variation in their orbits relates to the manner each type reacts to solar radiation pressure, resulting from the momentum of photons — quantum light particles emitted by the Sun — generating a minuscule force upon striking a solid object in space. This exchange of momentum from numerous photons over time can shift an object a little, resulting in acceleration or deceleration. Whereas a man-made object, like an empty rocket booster, behaves similarly to a lightweight can in the wind, a natural entity, such as an asteroid, would be considerably less influenced.