'Born from a cosmic crash': Earth's Minimoon may be a fragment of the Moon itself

Minimoon 2024 PT5

A newly discovered space rock called 2024 PT5, nicknamed a “Minimoon,” may be a fragment blasted off the Moon during a past impact event. Researchers suggest this is the second such object identified orbiting near Earth.

Evidence of a Larger Population

With a second possible lunar fragment now identified — the first being Kamo'oalewa in 2021 — scientists propose a hidden population of similar Moon-origin objects travelling in Earth-like orbits.

Unique Speed and Composition

Spotted in August 2024, 2024 PT5 moved unusually slowly at just 4.5 mph (2 m/s) relative to Earth. Spectral analysis revealed its composition closely matches that of Moon rocks retrieved by Apollo and Luna missions.

Tracking a Possible Source

The team suspects 2024 PT5 was ejected during a collision on the Moon. By matching its composition to lunar regions, they hope to identify the parent crater and better understand impact processes on airless bodies like the Moon.

Similar to Kamo'oalewa

Kamo'oalewa, the first known lunar fragment near Earth, follows a stable quasi-satellite orbit and shows signs of older space weathering. In contrast, 2024 PT5 briefly crossed Earth’s path before continuing its orbit and may be a fresher ejection.

Next Encounter Predicted for 2055

Though 2024 PT5 only stayed close to Earth for a short period in 2024, scientists expect it to align again with Earth’s orbit in 2055. Its temporary approach has helped boost interest in Earth-Moon system fragments.

Findings

The research, conducted as part of the MANOS survey, was led by Teddy Kareta and Nick Moskovitz from Lowell Observatory and published in January. Future telescopes like the Vera Rubin Observatory are expected to uncover more such hidden objects.