Astronomers announced today that a small asteroid, officially catalogued as 2025 PN7, has been orbiting the Sun in near-perfect step with our planet for the past six decades — effectively acting as a quasi-moon until at least 2083.
The object, roughly the size of a ten-story building (18–36 meters across), was first detected in late July 2025 by the Pan-STARRS 1 telescope atop Haleakalā, Hawaii. Follow-up observations from telescopes in Chile and Arizona quickly confirmed its unusual path: a near-1:1 orbital resonance with Earth.“It’s not gravitationally bound to us like the real Moon,” explained Dr. Sarah Kessler, lead researcher at NASA’s Center for Near-Earth Object Studies (CNEOS). “Instead, it’s locked in a stable ‘horseshoe’ dance with Earth as both of us circle the Sun.
From our perspective, it looks like a distant second moon trailing behind us.”2025 PN7 currently loops between 299,000 kilometers at its closest (farther than the actual Moon’s average 384,000 km) and 17 million kilometers at its most distant. It poses no collision risk and exerts no measurable influence on tides, earthquakes, or human affairs.
The quasi-moon has likely been in this configuration since around 1965, undetected until modern survey telescopes became sensitive enough to spot such faint, slow-moving objects against the star field.“This is a beautiful example of orbital mechanics in action,” said Paul Chodas, director of CNEOS. “Earth collects these temporary companions fairly often — we’ve known about a handful before — but 2025 PN7 is one of the longest-lasting we’ve ever tracked.”After 2083, gravitational tugs from the Sun and planets will nudge the asteroid out of its Earth-like orbit, sending it into a more traditional horseshoe pattern before it eventually drifts away entirely.
The discovery comes just one day after the actual Moon reached its New Moon phase on November 20 — the smallest and farthest New Moon until 2043 — creating a poetic coincidence of lunar headlines.While 2025 PN7 won’t be visible to the naked eye or even most backyard telescopes, professional astronomers plan to study it intensively over the coming decades to learn more about the population of near-Earth asteroids and the delicate gravitational balancing act that keeps our solar system running smoothly.
