Scientists Discover Potential ‘Minimoons’ Hidden Near Earth: What This Means for Our Planet

Recent research reveals that 2024 PT5, a small rocky body discovered last year, may actually be a piece of the moon. This “minimoon” could have been ejected during a massive impact, hinting at a larger group of lunar fragments orbiting near Earth.

“Finding just one object would be interesting, but discovering two suggests there’s a whole population,” said Teddy Kareta, a planetary scientist at Lowell Observatory. This insight came during his presentation at the 56th Lunar and Planetary Sciences Conference.

As Earth orbits the sun, it moves through a cloud of debris, which includes both human-made objects and leftover materials from ancient collisions in our solar system. These near-Earth objects (NEOs) require monitoring to ensure they’re not a threat.

Astronomers in South Africa spotted 2024 PT5 in August 2024. It was moving slowly, at just 4.5 mph, making it an appealing target for the Mission Accessible Near-Earth Object Survey (MANOS). Only nine other asteroids have been recorded traveling at such a leisurely pace.

Kareta and Nick Moskovitz, principal investigator for MANOS, have been fascinated by the idea of finding moon rocks in space ever since the first fragment was detected in 2021. They used the Lowell Discovery Telescope to study 2024 PT5 shortly after its discovery, expecting it would yield valuable information.

Analysis revealed that 2024 PT5’s composition closely resembles rocks collected during the Apollo missions and the Soviet Union’s Luna 24. Measuring 26 to 39 feet in diameter, it isn’t just another asteroid; researchers believe it’s a remnant of a past lunar impact.

This research opens doors to understanding how planetary bodies, especially those without tectonic activity, change due to impacts. Identifying where lunar fragments come from can shed light on how collisions reshape these celestial bodies.

To better illustrate this, Kareta likens discovering new fragments to finding fresh evidence at a crime scene. “It’s like realizing there’s a new kind of evidence you didn’t know existed,” he said. While it might not immediately solve the mystery, every detail counts.

Material from the Earth-Moon system is likely to enter orbits around our planet post-impact. In a metaphorical sense, 2024 PT5 and Earth travel like cars on a highway—Earth moves rapidly, while 2024 PT5 meanders more slowly before they cross paths again in 2055.

In total, 2024 PT5 is the second identified lunar fragment. The first, Kamo’oalewa, was recognized in 2021 and has a longer orbital history and different characteristics. Kamo’oalewa’s orbit allows it to linger near Earth, providing an intriguing comparison. Recent studies suggest it may originate from a significant lunar impact that created the Giordano Bruno crater on the moon’s far side.

Researchers believe there are more fragments waiting to be found. Kareta suspects some asteroids might have been misidentified and could potentially be pieces of the moon. This emphasizes the importance of precise tracking and understanding of NEOs, as misclassifying an object could change our understanding of potential threats to Earth.

As technology improves, so does the potential for discoveries. The Vera Rubin Observatory is set to come online soon and is expected to help uncover more dim celestial objects. Kareta is optimistic that expanding our knowledge of lunar fragments will encourage other researchers to delve deeper into this fascinating area of study.

This research was published in January in The Astrophysical Journal Letters.

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