Astronomers have identified an asteroid spinning at a speed previously thought impossible for objects of its size, challenging existing theories about asteroid composition and structural integrity. The discovery, made by researchers analyzing early data from the Vera C. Rubin Observatory in Chile, marks a significant moment in planetary science.
The Record-Breaking Asteroid
The asteroid, designated 2025 MN45, measures approximately 710 meters in diameter and completes a full rotation in just 1.92 minutes. This makes it the fastest-spinning large asteroid ever observed, exceeding the theoretical limits for “rubble pile” asteroids—the loose collections of rocks and dust that make up most space rocks.
How Was This Possible?
The typical expectation is that asteroids held together loosely by gravity would disintegrate if spun too quickly. The current speed of 2025 MN45 means it must be made of much stronger material than scientists expected. The asteroid is likely either a single, solid rock or even composed of metal, as even clay would not hold it together at that speed.
What This Means for Space Rock Science
The Rubin Observatory’s first nine nights of observations revealed 76 asteroids with calculable rotation periods, including 19 “super-fast” rotators spinning in under 2.2 hours. But the discovery of three “ultra-fast” rotators, including MN45, suggests that asteroids can spin much faster than previously thought. This finding suggests that our understanding of how these asteroids are formed and held together is incomplete.
The Rubin Observatory’s Role
The Vera C. Rubin Observatory is expected to continue spotting even more asteroids as it completes its 10-year survey of the southern sky. This will allow scientists to explore the surprising diversity of these space rocks further and refine our understanding of asteroid composition and stability.
The discovery of 2025 MN45 underscores how much we still have to learn about the formation and dynamics of asteroids. Further research is necessary to determine how these ultra-fast rotators manage to maintain their structure against centrifugal forces.
