A powerful new telescope in South America is already offering tantalizing hints of what it can do.
The Vera C. Rubin Observatory began studying the heavens from a Chilean mountaintop last spring, and its “first light” images wowed astronomers and space fans alike when they were released in June.
That initial dataset included observations of nearly 2,000 newly discovered asteroids, and we got some exciting new details about this group on Wednesday (Jan. 7). A new study reveals that 19 of the asteroids are “superfast rotators,” completing one spin in less than 2.2 hours — and one is the fastest-spinning big asteroid ever found.
Like all but one of the newfound superfast rotators, the record-setting space rock, called 2025 MN45, resides in the main asteroid belt between Mars and Jupiter. The object measures about 0.4 miles (710 meters) across and completes one rotation every 1.88 minutes, making it “the fastest-spinning asteroid with a diameter over 500 meters that astronomers have found,” according to a statement released Wednesday by the U.S. National Science Foundation’s NOIRLab. (The Rubin Observatory is a joint program of NOIRLab and the Department of Energy’s SLAC National Accelerator Laboratory.)
An asteroid’s rotation rate can reveal key information about it. Extremely rapid spins, for example, may point to a violent collision that shattered a larger parent body. Rotation can also offer insight into an asteroid’s internal structure and composition.
“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,” study leader Sarah Greenstreet, an NSF NOIRLab assistant astronomer and the head of the Rubin Observatory’s Solar System Science Collaboration’s Near-Earth Objects and Interstellar Objects working group, said in the same statement.
“We calculate that it would need a cohesive strength similar to that of solid rock,” she added. “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.”
2025 MN45 isn’t the overall spin-rate record holder. Astronomers have found a number of small asteroids — those just a few meters, or tens of meters, wide — that complete a rotation in less than a minute.
The Vera Rubin Observatory is still ramping up operations and has not yet begun its primary science mission. That effort, a 10-year project called the Legacy Survey of Space and Time (LSST), will create a wide-view, high-definition, time-lapse record of the universe. The survey will rely on images captured by the 3.2-billion-pixel LSST Camera, the largest digital camera in the world.
“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,” Aaron Roodman, deputy head of LSST and professor of particle physics and astrophysics at SLAC, said in the same statement.
“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,” he added.
The new study was published Wednesday in The Astrophysical Journal Letters. The results were also presented during a press conference that day at the 247th meeting of the American Astronomical Society in Phoenix, Arizona.