Newly discovered asteroid spins at record-breaking speed
The Vera C. Rubin Observatory detected nearly 2,000 new asteroids in about 10 hours, including MM45, rotating in under two minutes.
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A crop of asteroids discovered by the new Vera C. Rubin Observatory is wowing astronomers, with one of the space rocks spinning at a record-breaking speed.
Among the nearly 2,000 asteroids detected last year by the telescope operated by the National Science Foundation’s NOIRLab and SLAC National Accelerator Laboratory, 19 are classified as super-fast or ultra-fast rotators.
A new study published in The Astrophysical Journal Letters revealed that one of these objects is the fastest-known asteroid larger than 500 meters, completing a full rotation in about two minutes. The study examined 76 asteroids, including 16 super-fast rotators spinning between 13 minutes and 2.2 hours. Three ultra-fast rotators complete a full spin in less than five minutes, including asteroid MM45, which rotates every 1.88 minutes.
Such rapid rotation is notable because most asteroids are considered “rubble piles,” made up of smaller rocks held together primarily by gravity.
This artist’s illustration depicts 2025 MN45 — the fastest-rotating asteroid with a diameter over 500 meters that scientists have ever found. The asteroid is shown surrounded by many other asteroids, depicting its location within the main asteroid belt. The Sun and Jupiter are shown in the distance. (Image credit: NSF–DOE Vera C. Rubin Observatory/NOIRLab/SLAC/AURA/P. Marenfeld)
Spin rates can provide astronomers with clues about an asteroid’s composition. According to NOIRLab, fast rotation requires an object to have significant internal strength.
The asteroid, roughly the size of eight American football fields, must be made of exceptionally strong material to avoid flying apart as it spins around every 1.88 minutes.
“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,” said study author Sarah Greenstreet, with NOIRLab. “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.”
Another newly discovered asteroid is not far behind MM45, with a rotation period of about 1.9 minutes.
NSF–DOE Vera C. Rubin Observatory is seen with its dome open during First Look observation activities in April 2025. Messier 41, the Little Beehive Cluster, can be seen over the telescope in this telelens photo. (Image credit: RubinObs/NOIRLab/SLAC/NSF/DOE/AURA/P. Horálek (Institute of Physics in Opava)
What also stands out is how quickly these discoveries were made — over just 10 hours of observations rather than months. Rubin’s Legacy Survey of Space and Time (LSST) will eventually create the largest astronomical movie of the Southern Hemisphere night sky over a 10-year period, and astronomers are eager to see what else it uncovers.
“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 and professor of particle physics and astrophysics at SLAC. “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.”
The National Science Foundation and U.S. Department of Energy-funded observatory is named after the late astronomer Vera Rubin, who provided the first convincing evidence for dark matter.
The LSST is expected to begin full operations in 2026 and will use the largest digital camera ever built.
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