"Quasi-Moon" Discovered Orbiting Earth for Decades

EARTH, Laniakea Supercluster—Astronomers have announced the discovery of a new “quasi-moon” of Earth: a nearby asteroid dubbed 2025 PN7 that appears to have been shadowing the planet in orbit for decades, though it doesn’t orbit Earth in the same way our Moon does.

The asteroid, which measures roughly 19 meters (62 feet) across, is extremely faint, with an apparent magnitude of about 26, making it detectable only with powerful telescopes. It was first spotted on Aug 29, 2025, by the Pan-STARRS1 telescope atop Haleakalā in Hawaii. Archival data suggests that the rock has been loosely orbiting Earth for about 60 years and could continue in this peculiar arrangement for another six decades.

A quasi-moon is not a true satellite. Instead, it shares Earth’s orbital path around the Sun in a way that makes it look as if it is temporarily orbiting the planet. 2025 PN7 is considered one of Earth’s least stable quasi-satellites to date, slipping in and out of gravitational resonance.

The designation was first proposed by French journalist and amateur astronomer Adrien Coffinet, who stated that his calculations made it appear that 2025 PN7 was a quasi-moon in a post on the Minor Planet Mailing List on Aug 30.

“2025 PN7 seems to be a quasi-satellite of the Earth for the next 60 years,” Coffinet wrote.

Carlos de la Fuente Marcos of the Complutense University of Madrid
told Live Science why the discovery may have long remained hidden: “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.”

While the object poses no threat to Earth, its discovery adds to a growing list of quasi-moons and provides astronomers with new material to refine orbital models and test detection techniques. With upcoming observatories like the Vera Rubin Observatory set to scan the skies in unprecedented detail, scientists expect more hidden companions to be revealed. For now, 2025 PN7 stands as a reminder that Earth’s neighborhood is still full of surprises—shadowy wanderers that slip past unnoticed until the right telescope locks eyes on them.