Newly Discovered Asteroid Hints at a Hidden Population of Earth’s ‘Quasi-Moons’
BOSTON - Earth is currently accompanied by a recently discovered asteroid, 2025 PN7, that orbits our planet as a “quasi-moon,” and experts believe it’s just one of perhaps at least six others sharing a similar, temporary relationship with Earth.The discovery, made in July by researchers at the University of Hawaii using the Pan-STARRS telescope in Haleakala, Hawaii, sheds light on a previously underappreciated population of objects gravitationally influenced by Earth.
These “quasi-moons” aren’t true satellites like our Moon, but rather asteroids that follow a complex orbital dance with Earth, remaining in a stable configuration for decades before drifting off into space. 2025 PN7 is expected to remain a companion to Earth until 2083, a substantially longer period than the few months Earth shared with asteroid 2024 PT5 last year.
“These objects are all on similar orbits to the Earth and remain reasonably stable over many years,” explains Jonathan Blazek, an astrophysicist at Northeastern University. “In the long term, the orbits will drift, and the quasi-moons will move away. 2025 PN7 is expected to stick around for roughly another 60 years.”
The Pan-STARRS telescope is specifically designed to identify new objects within our solar system and track transient astronomical events like supernovae. Though, the upcoming Rubin Observatory, which began collecting data earlier this year, is poised to dramatically increase the rate of discovery of these solar system objects.”The Rubin Observatory…is an even larger telescope that will find many new solar system objects,” says Blazek, who is involved with the project.
Despite its orbital proximity, 2025 PN7 poses no threat to Earth. Experts estimate the asteroid is approximately 20 meters in diameter – roughly the size of a small office building – and therefore has a negligible gravitational impact. blazek notes that the Moon is about a quadrillion (10^15) times more massive than the quasi-moon, and McCleary adds that it’s far too small to measurably affect Earth’s tides.
