Fastest-Spinning Asteroid Discovered by Rubin Observatory

Scientists analysing the first images from the Vera C. Rubin Observatory have identified the fastest-spinning asteroid ever observed in its size category. The asteroid, designated 2025 MN45, offers rare insights into asteroid composition and the early evolution of the solar system, marking a significant milestone for next-generation astronomical surveys.

Record-Breaking Rotation and Size

Asteroid 2025 MN45 measures about 2,300 feet (around 710 metres) in diameter, making it larger than most skyscrapers on Earth. Despite its size, it completes one full rotation in just 113 seconds. This makes it the fastest-spinning known asteroid larger than 500 metres across. Such a rapid spin challenges existing assumptions about the structural limits of large asteroids.

Discovery Through Rubin Observatory Survey

The asteroid was discovered using preliminary data from the Vera C. Rubin Observatory, whose LSST Camera is the largest digital camera ever built. The finding is part of an ongoing asteroid survey designed to improve understanding of how small solar system bodies formed and evolved. The results were published in The Astrophysical Journal Letters and represent the first peer-reviewed paper based on Rubin Observatory data.

Implications for Asteroid Composition

The extreme spin rate suggests that 2025 MN45 is not a typical “rubble pile” asteroid, which consists of loosely bound rocks and debris. According to researchers, it must possess internal strength comparable to solid rock to avoid breaking apart. This is notable because most large asteroids are believed to require a minimum rotation period of about 2.2 hours to remain intact. The asteroid is located in the main belt between Mars and Jupiter, where such fast rotators are rare.

Imporatnt Facts for Exams

• 2025 MN45 rotates once every 113 seconds, a record for its size class.
• The asteroid is about 710 metres wide and located in the main asteroid belt.
• The discovery used data from the LSST Camera at the Rubin Observatory.
• Most large asteroids are “rubble piles” with much slower rotation periods.

Future Discoveries from Rubin Observatory

The Rubin Observatory’s commissioning data has already revealed around 1,900 previously unknown asteroids. In addition to 2025 MN45, scientists identified several other super-fast and ultra-fast rotators. When the observatory formally begins its 10-year sky survey in the coming months, astronomers expect a dramatic increase in such discoveries, further reshaping knowledge of asteroid dynamics and solar system history.