Massive asteroid defies spin limits with a 1.9-minute rotation

Astronomers using the Vera C. Rubin Observatory observed a 710-meter asteroid, 2025 MN45, completing a rotation in 1.9 minutes—far faster than the ~2.2-hour limit for an object of its size—hinting at a solid rock or metal composition and prompting a rethink of asteroid rotational physics, based on data published in The Astrophysical Journal Letters.