Astronomers say they’ve found an asteroid that spins faster than other space rocks of its size.
The asteroid, known as 2025 MN45, is nearly half a mile (710 meters) in diameter and makes a full rotation every 1.88 minutes, based on an analysis of data from the Vera C. Rubin Observatory. “This is now the fastest-spinning asteroid that we know of, larger than 500 meters,” University of Washington astronomer Sarah Greenstreet said today at the American Astronomical Society’s winter meeting in Phoenix.
Greenstreet, who serves as an assistant astronomer at the National Science Foundation’s NOIRLab and heads the Rubin Observatory’s working group for near-Earth objects and interstellar objects, is the lead author of a paper in The Astrophysical Journal Letters that describes the discovery and its implications. It’s the first peer-reviewed paper based on data from Rubin’s LSST Camera in Chile.
2025 MN45 is one of more than 2,100 solar system objects that were detected during the observatory’s commissioning phase. Over time, the LSST Camera tracked variations in the light reflected by those objects. Greenstreet and her colleagues analyzed those variations to determine the size, distance, composition and rate of rotation for 76 asteroids, all but one of which are in the main asteroid belt between the orbits of Mars and Jupiter. (The other asteroid is a near-Earth object.)
The team found 16 “super-fast rotators” spinning at rates ranging between 13 minutes and 2.2 hours per revolution — plus three “ultra-fast rotators,” including 2025 MN45, that make a full revolution in less than five minutes.
