Astronomers Discover Unusual Asteroid Spinning Faster Than Anything Its Size

Researchers have identified 19 super- and ultra-fast-rotating asteroids, including one that is the fastest-spinning asteroid of its kind.

Researchers found the astronomical ballerinas using data from the world’s largest digital camera, located at the NSF–DOE Vera C. Rubin Observatory in Chile, during the observatory’s early commissioning phase. Their exciting results, described in a study published yesterday in The Astrophysical Journal Letters, are just a taste of the insights scientists expect Rubin to shed on the workings of the universe once it begins its Legacy Survey of Space and Time (LSST).

“As this study demonstrates, even in early commissioning, Rubin is successfully allowing us to study a population of relatively small, very-rapidly-rotating main-belt asteroids that hadn’t been reachable before,†lead author Sarah Greenstreet, also lead of Rubin Observatory’s Solar System Science Collaboration’s Near-Earth Objects and Interstellar Objects working group, said in a NOIRLab statement.

Fastest-spinning known asteroid of its kind

The rotational speed of an asteroid as it orbits the Sun can provide insight into its ancient formation, as well as its inner composition and lifelong development. For example, a fast spinner may be the result of an impact with a fellow asteroid, indicating its potential state as a fragment.

The paper highlights 76 asteroids, including 16 super-fast rotators (with rotation periods between around 13 minutes and 2.2 hours) and three ultra-fast rotators (with rotation periods of less than five minutes). These 19 asteroids are all longer than an American football field (around 90 meters). A champion among them, 2025 MN45, is the fastest-spinning known asteroid of objects larger than 0.3 miles (500 meters); 2025 MN45 has a diameter of 0.4 miles (710 meters) and rotates once every 1.88 minutes. It’s also one of five asteroids found by the team that are some of the fastest-spinning known asteroids under 0.6 miles (1 kilometer).

“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,†Greenstreet said. “We calculate that it would need a cohesive strength similar to that of solid rock. This is somewhat surprising since most asteroids are believed to be what we call ‘rubble pile’ asteroids, which means they are made of many, many small pieces of rock and debris that coalesced under gravity during Solar System formation or subsequent collisions.†The densities of these rubble piles determine how fast they can rotate without fragmenting.

Legacy Survey of Space and Time

The majority of fast-rotating asteroids identified by researchers are near-Earth objects (NEOs), meaning they orbit the Sun not far outside of Earth’s path. The orbit of main-belt asteroids (MBAs) takes them between Jupiter and Mars, and we know of fewer of these mostly due to the fact that they’re farther from us, making them more challenging to spot. Most of the recently discovered fast rotators are in the main asteroid belt or slightly farther out, emphasizing how far out researchers are able to identify these exceptionally fast twirlers thanks to the Rubin Observatory’s abilities.

Rubin’s Legacy Survey of Space and Time, slated to begin this year, should reveal more fast rotators and supply data regarding their compositions, strengths, and collisional histories. It will scan the Southern Hemisphere night sky for a decade to produce a magnificent time-lapse of the universe. The team’s research represents the first published peer-reviewed scientific paper to use information from the LSST Camera, the biggest camera ever built.

“We have known for years that Rubin would act as a discovery machine for the Universe, and we are already seeing the unique power of combining the LSST Camera with Rubin’s incredible speed. Together, Rubin can take an image every 40 seconds,†said Aaron Roodman, Deputy Head of LSST. “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.â€