New research suggests that at any given time, Earth may temporarily capture up to half a dozen fragments from the moon, known as minimoons, before they continue their journey around the sun.
However, due to their small size and rapid movement, these objects are difficult to detect, reported Space.com.
When impacts occur on the moon, they eject debris into space. While some larger pieces may be launched, most of the fragments are small—under 6.5 feet (2 meters) wide—and travel at high speeds. Typically, this lunar debris ends up in solar orbit, but occasionally, some of it is briefly caught by Earth’s gravity before resuming its path around the sun, according to a study published in the journal Icarus.
It’s “kind of like a square dance, where partners change regularly and sometimes leave the dance floor for a while,” Robert Jedicke, a researcher at the University of Hawaii and lead author of the study, told Space.com by email.
While the International Astronomical Union hasn’t officially defined what a minimoon is, earlier studies suggest it refers to an object that is temporarily gravitationally bound to Earth, completes at least one orbit, and comes within roughly four times the Earth-moon distance during its path.
Minimoons can originate from various parts of the solar system, but a 2018 study proposed that most come from the asteroid belt located between Mars and Jupiter. However, recent discoveries of minimoons with apparent lunar origins are challenging that theory.
In 2016, Hawaii’s Pan-STARRS1 asteroid survey telescope detected a near-Earth object, named Kamo’oalewa (or 469219 Kamo’oalewa), measuring between 131 and 328 feet (40 to 100 meters) wide.
Though it orbits the sun alongside Earth, later research showed it likely originated from the moon, possibly ejected during the impact that created the Giordano Bruno crater 1 to 10 million years ago.
More recently, astronomers reported another temporary Earth satellite, 2024 PT5, which was discovered last year. Its composition appears to resemble the moon more than an asteroid, further supporting the idea that some minimoons may be fragments of lunar material.
