Earth May Capture Up to Six Minimoons at Any Given Time

Recent research indicates that Earth could temporarily capture as many as six fragments from the Moon, known as 'minimoons,' simultaneously orbiting the planet. These celestial bodies, typically less than 2 meters in diameter, are ejected from the Moon during impact events and can be briefly held by Earth’s gravity before continuing their journey around the Sun. The findings were published in a study in the journal Icarus on July 14, 2025.

Robert Jedicke, a researcher at the University of Hawaii and the lead author of the study, explained that when lunar impacts occur, small debris is ejected into space. While larger debris may escape into solar orbit, many fragments remain small and fast-moving, making detection challenging. 'It's kind of like a square dance, where partners change regularly and sometimes leave the dance floor for a while,' Jedicke stated in correspondence with Space.com.

The International Astronomical Union (IAU) has not officially defined the term 'minimoon.' However, previous research suggests that these objects are temporarily gravitationally bound to Earth, completing at least one orbit and coming within four times the Earth-Moon distance during their path. Minimoons can originate from various locations in the solar system, although a 2018 study indicated that most are believed to come from the asteroid belt situated between Mars and Jupiter.

In a significant development, recent discoveries challenge this theory, suggesting that some minimoons may indeed be fragments of the Moon. For instance, in 2016, the Pan-STARRS1 asteroid survey telescope in Hawaii detected a near-Earth object named Kamo'oalewa (or 469219 Kamo'oalewa), which measures between 40 and 100 meters in diameter. Although this object orbits the Sun alongside Earth, research indicated its likely lunar origin, possibly ejected during the impact that created the Giordano Bruno crater between 1 and 10 million years ago.

The implications of these findings are profound as they suggest a more complex relationship between Earth and its natural satellite. More recently, astronomers reported another temporary Earth satellite, designated 2024 PT5, discovered last year, which appears to share a composition more akin to the Moon than an asteroid. This further supports the notion that some minimoons are indeed remnants of lunar material.

The notion of minimoons captures the interest of both scientists and enthusiasts alike, as it opens new avenues for understanding the dynamics of celestial bodies in our solar system. Future studies may provide more insight into the origins and behaviors of these transient objects, enhancing our grasp of planetary interactions and the history of our own Moon. As technology advances, the prospect of detecting and studying minimoons could pave the way for significant discoveries in the fields of astronomy and planetary science.