Rubin Observatory spots fastest-spinning asteroid over 500 meters

Rubin Observatory data identified 2025 MN45, a roughly 710-meter main-belt asteroid that rotates every 1.88 minutes, and a peer-reviewed paper reports 76 measured asteroid rotation periods including 19 new super- and ultra-fast rotators.

Rubin Observatory data have revealed the fastest-spinning asteroid known with a diameter over 500 meters. The discovery appears in a peer-reviewed paper that is the first to use data from Rubin's LSST Camera. Researchers measured rotation periods for 76 asteroids during early commissioning observations. The results provide new information about asteroid structure and composition. Key findings: - The study presents 76 asteroids with reliable rotation periods measured from Rubin commissioning data. - Nineteen newly identified fast rotators are longer than about 90 meters; 16 have periods roughly between 13 minutes and 2.2 hours, and 3 have periods under 5 minutes. - The fastest main-belt asteroid reported, 2025 MN45, is about 710 meters in diameter and completes a rotation every 1.88 minutes. - Most of the new fast rotators are located in the main asteroid belt, with one identified as a near-Earth object. - Other notable fast rotators listed include 2025 MJ (1.9-minute period), 2025 MK (3.8 minutes), 2025 MV (13 minutes), and 2025 MG (16 minutes). - The paper appears in The Astrophysical Journal Letters and was presented at the AAS 247 meeting. Summary: The measurements show that some main-belt asteroids at several-hundred-meter scales can rotate far more rapidly than previously recorded, and the team calculates that 2025 MN45 would require cohesive strength similar to solid rock to remain intact. Rubin's light-collecting power and precise measurements made these detections at greater distances than earlier surveys. Scientists expect more such discoveries as the Rubin Observatory begins its decade-long Legacy Survey of Space and Time.