The Vera C. Rubin Observatory, a state-of-the-art telescope in Chile, has identified the fastest-spinning large asteroid ever observed. This discovery showcases the observatory’s early potential, even before its main science mission begins. The asteroid, designated 2025 MN45, completes one rotation in just 1.88 minutes, a record among asteroids larger than 500 meters in diameter.
Unprecedented Spin Rate
The asteroid resides in the main belt between Mars and Jupiter and measures approximately 0.4 miles (710 meters) across. Its extreme spin rate is noteworthy, as it challenges existing assumptions about asteroid composition and formation.
“Clearly, 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,” explains Sarah Greenstreet, lead study author and astronomer at NSF NOIRLab.
This suggests the asteroid is not a typical “rubble pile” – a loosely bound collection of debris – but rather composed of solid rock. This finding is surprising, given that most asteroids are believed to have formed from such loose aggregations of material.
What This Means
An asteroid’s rotation rate reveals critical information about its history. Rapid spins often indicate catastrophic collisions, where a larger parent body was shattered into fragments. The rate also gives clues about the asteroid’s internal structure and the strength of its materials.
The Vera Rubin Observatory has already identified 19 other “superfast rotators” – asteroids spinning in less than 2.2 hours – but none have matched 2025 MN45’s extreme velocity.
The Legacy Survey of Space and Time
This discovery is just a preview of what the Rubin Observatory will deliver. Its ten-year Legacy Survey of Space and Time (LSST) will use a 3.2-billion-pixel camera to create a high-definition time-lapse record of the universe.
“The ability to find thousands of new asteroids in such a short period of time, and learn so much about them, is a window into what will be uncovered during the 10-year survey,” says Aaron Roodman, LSST deputy head.
The observatory can capture an image every 40 seconds, making it a powerful discovery engine. The Rubin Observatory is expected to revolutionize our understanding of the solar system and beyond.
The rapid identification of this superfast asteroid demonstrates the observatory’s capacity for breakthrough discoveries. This heralds a new era of asteroid research and a deeper understanding of the violent processes that shape our solar system.
