Tumbling through Earth’s increasingly crowded orbit are about 5,000 satellites, half a million pieces of human-made debris and only one confirmed natural object: the moon. Now, astronomers working out of the University of Arizona’s Steward Observatory think they may have discovered a second natural satellite — or at least a temporary one.
Meet 2020 CD3, Earth’s newest possible “minimoon.”
A minimoon, also known as a temporarily captured object, is a space rock that gets caught in Earth’s orbit for several months or years before shooting off into the distant solar system again (or burning up in our planet’s atmosphere).
Related: Could the moon act as a fishing net for extraterrestrial life?
While astronomers suspect there is at least one minimoon circling Earth at any given time, these tiny satellites are rarely discovered, likely because of their relatively small size. Until now, only one confirmed minimoon has ever been detected: a 3–foot-wide (0.9 meters) asteroid called 2006 RH120, which orbited Earth for 18 months in 2006 and 2007.