Earth Has a Small 'Quasi-Moon'

A small asteroid has been quietly following the Earth around the sun for decades, and this "quasi-moon" is expected to stick around for a while longer before shooting off into space. The asteroid dubbed 2025 PN7 was first detected in August by the Pan-STARRS observatory in Hawaii, but astronomers say it's likely been around since 1957, reports the New York Times. At an estimated 62 feet long, the asteroid might be the smallest quasi-moon yet discovered, though its exact size remains uncertain because of limited observations.

Unlike traditional moons, quasi-moons don't circle Earth directly. Instead, they follow their own orbits around the sun that closely match Earth's path, effectively shadowing the planet for decades or centuries at a time, per Live Science. Astronomers believe 2025 PN7 made its closest approach at about 2.5 million miles away in 1980, and they expect it to remain close to Earth until around 2083.

"It is small, faint, and its visibility windows from Earth are rather unfavorable, so it is not surprising that it went unnoticed for that long," says Carlos de la Fuente Marcos of the Complutense University of Madrid, co-author of the study in the journal Research Notes of the American Astronomical Society.