The asteroid was found in the first images from the Vera C. Rubin Observatory
PHOENIX — A newly discovered asteroid is spinning about as fast as a Ferris wheel. With a rotation period of just 112 seconds, it is the new record holder for the fastest rotating asteroid over a width of more than 500 meters. Scientists believe it must be made of solid rock to avoid breaking.
“It’s unlike anything we’ve ever seen before,” said astronomer Sarah Greenstreet. during a January 7 press conference at a meeting of the American Astronomical Society. Previous record holders had rotation periods of around 30 minutes to an hour. “This makes our asteroid spin the fastest, much faster than anything we’ve reliably known before,” she says.
The rock, named 2025 MN45, is one of the first asteroids discovered by the Vera C. Rubin Observatory in Chile. Rubin is imagine the whole southern sky every few nights for 10 years, giving it an unprecedented view of celestial objects that move and change, like asteroids.
Rubins “first look” imagesfilmed over nine nights last spring and released in June, contained about 2,100 solar system objects, about 90 percent of which had never been seen before. By observing how the brightness of the asteroids in this set changed over time, astronomers measured the rotation periods of 76 of them.
“Rotation rates are important because they are one of the only ways to know the internal force, composition and collision history of asteroids,” said Greenstreet, of the University of Washington in Seattle. Rapid rotation means an asteroid must be strong enough to hold itself together. Most large asteroids with known densities are loosely related »pile of rubble” which would collapse if they rotated faster than once every 2.2 hours.
Sixteen of the asteroids Rubin discovered were spinning faster than this limit, Greenstreet said. Three of them were spinning faster than once every five minutes – about the previous record for fast-spinning asteroids of this size. (Smaller ones can spin faster because they have less material to hold on to.)
All ultrafast rotators, including the 2025 MN45, are likely made of solid rock or clay, Greenstreet said. 2025 MN45 may have been released from the dense core of a larger parent body after a massive collision.
“We think there could potentially be a lot” of these fast spinners in the belt between Mars and Jupiter, Greenstreet said. Learning more about the diversity of asteroids can help astronomers piece together the history of our solar system.
