Scientific America – Newfound ‘Quasi-Moon’ Has Been Earth’s Fellow Traveler for Thousands of Years

Astronomers have identified asteroid 2023 FW13 as a “quasi-moon” or “quasi-satellite,” meaning it orbits the sun in a similar timeframe as Earth but is only slightly influenced by Earth’s gravity. This asteroid, about 50 feet in diameter, orbits the sun while also circling Earth, coming within 9 million miles of our planet.

First observed in March 2023 by the Pan-STARRS observatory in Hawaii, its existence was confirmed by other observatories and officially listed by the Minor Planet Center. Estimates suggest 2023 FW13 has been following this path since at least 100 B.C. and will continue until around A.D. 3700. Despite its proximity, it poses no collision threat to Earth. Another quasi-satellite, Kamo’oalewa, was discovered in 2016 and may be a fragment of the moon.