What asteroid, observed by the Vera C. Rubin Observatory in January 2026, has the fastest spin of any known asteroid larger than 0.5 km, completing a rotation every 1.88 minutes?

Astronomers recently made a remarkable discovery using data from the Vera C. Rubin Observatory: an asteroid, designated 2025 MN45, that boasts the fastest spin rate of any known asteroid larger than 0.5 kilometers. Observed during the observatory's "First Look" event, this celestial body completes a full rotation in an astonishing 1.88 minutes. This rapid rotation is particularly significant because most asteroids of this size, often thought to be loosely bound "rubble piles," would be torn apart by such extreme centrifugal forces.

The asteroid 2025 MN45 measures approximately 710 meters (0.44 miles) in diameter, making its swift rotation a puzzle for scientists. Its ability to remain intact despite spinning so quickly suggests that it must possess a cohesive strength akin to solid rock, rather than a collection of smaller fragments held together by gravity. This finding provides crucial new insights into asteroid composition and evolution, challenging existing models of how these objects form and behave in our solar system.

The Vera C. Rubin Observatory, with its powerful LSST Camera, is uniquely capable of detecting such faint and fast-moving objects. The initial observations that led to the discovery of 2025 MN45 were among the first peer-reviewed scientific papers to utilize data from this groundbreaking observatory. As the Rubin Observatory continues its decade-long Legacy Survey of Space and Time, astronomers anticipate many more discoveries that will deepen our understanding of the universe and the dynamic objects within our own solar system.