In a milestone announced this month, astronomers at the University of Washington, using preliminary data from the Vera C. Rubin Observatory in Chile, have identified the fastest‑spinning asteroid ever recorded of its size: a main‑belt object designated 2025 MN45. Clocking a complete rotation every 1.88 minutes—about 113 seconds—the asteroid measures approximately 710 meters (0.44 miles) across, making it larger than eight American football fields or more than twice the length of the Empire State Building. This discovery marks the first peer‑reviewed scientific result based on data from the observatory’s LSST Camera, the largest digital camera in the world.

The findings were published on January 7, 2026, in the Astrophysical Journal Letters and presented at the American Astronomical Society’s 247th meeting in Phoenix, Arizona. The observations were gathered during the telescope’s early commissioning phase—spanning roughly 10 hours over seven nights between April and May 2025—and included nearly 1,900 previously unknown asteroids of which 19 were identified as “fast‑rotators.” Among these, 16 were classified as super‑fast rotators (spin periods between 13 minutes and 2.2 hours), and three—including 2025 MN45—were ultra‑fast, completing rotations in under five minutes.

To remain intact at such breakneck speed, 2025 MN45 must possess a cohesive strength similar to solid rock. This contrasts with the typical “rubble‑pile” asteroids—loosely bound aggregates of rock whose spin rates are limited by gravitational cohesion to about 2.2 hours per rotation in the main asteroid belt. The discovery therefore challenges prevailing assumptions about asteroid structure and suggests a much stronger internal composition.

Lead author Sarah Greenstreet, a University of Washington affiliate assistant professor of astronomy and NSF NOIRLab scientist, commented that the finding was “incredible,” especially considering that it arose from some of the observatory’s very first images. She emphasized that even in its early commissioning stage, the Rubin Observatory is proving capable of accessing previously unreachable parts of the asteroid population with exceptional sensitivity.

Beyond 2025 MN45, the team noted other rapid rotators including 2025 MJ71 (1.9‑minute rotation), 2025 MK41 (3.8 minutes), 2025 MV71 (13 minutes), and 2025 MG56 (16 minutes). The wider dataset—76 asteroids with reliable rotation measurements—reveals the Rubin Observatory’s unique capacity to detect small, fast‑spinning objects in the distant main belt. Once the full 10‑year Legacy Survey of Space and Time (LSST) begins in the coming months, scientists expect to exponentially expand knowledge of asteroid compositions, internal structure, and collisional histories.

Why this matters locally: While this discovery unfolds far beyond Earth, its implications ripple closer to home. Understanding asteroid composition and behavior directly informs planetary defense strategies—including predicting how objects might fragment or withstand stress during close approaches. Additionally, the University of Washington’s role in developing key detection software via the DiRAC Institute underscores the institution’s global scientific leadership, reinforcing local pride and influence in cutting‑edge astronomy.

The breakthrough also signals that the Rubin Observatory—equipped with the world’s largest digital camera and powered by UW‑developed software—will unlock countless new discoveries in our solar system. From revealing the strength of primitive bodies to refining models of early solar system formation, the findings highlight the intersection of local expertise and global exploration.