Rubin Observatory Spots a Record-Breaking, Fast-Spinning Asteroid

The NSF–DOE Vera C. Rubin Observatory in Chile is already living up to its reputation as the most prolific sky scanner ever built. In an announcement dated January 7, 2026, astronomers reported that even in pre-survey observations, the observatory discovered asteroid 2025 MN45, a roughly 710-meter-wide object that completes a full rotation every 1.88 minutes. That makes it the fastest-spinning asteroid larger than 500 meters ever found.

Spinning that quickly is remarkable because most large asteroids are loose rubble piles that would fly apart at such speeds. “This asteroid must be made of material that has very high strength in order to keep it in one piece as it spins so rapidly,” said lead astronomer Sarah Greenstreet. The team identified 19 super- and ultra-fast-rotating asteroids in all, with 2025 MN45 the standout. The observatory’s First Look event in June 2025 had already turned up thousands of asteroids, about 1,900 of them never seen before.

“Rubin Observatory in Chile is already living up to its reputation as the most prolific sky scanner ever built.”

Rubin’s power comes from a giant digital camera paired with a wide-field telescope that can image enormous swaths of sky in quick succession, capturing how objects move and change over days. Full survey operations were set to begin in early 2026, and in its first year alone scientists expect Rubin to discover on the order of a million new asteroids, transforming our census of the small bodies sharing the Solar System.

For now, the findings are based on early data rather than the decade-long survey to come, so catalogs and orbits will keep being refined as more observations roll in. But the early haul is a powerful preview. A telescope that can flag a tiny, blisteringly fast asteroid in its first nights of looking promises a flood of discoveries, including better tracking of near-Earth objects, that will keep astronomers busy for years.