Two large asteroids found spinning as fast as a fairground ride — SkimNews
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- Dmitrii Vavilov at the University of Washington and colleagues analyzed first-light data from the Vera C. Rubin Observatory in Chile, which began its 10-year sky survey in June 2026, measuring rotation for 260 asteroids out of a sample of more than 9,000 based on brightness changes from irregular shapes.
- 66 of the 260 were classified as super-fast rotators with rotation periods under 2.2 hours, the threshold at which self-gravity alone should no longer hold an asteroid together.
- Two main-belt asteroids between Mars and Jupiter, each wider than 2 kilometers, were found completing one full rotation every 5 minutes — a speed never before recorded for asteroids of that size.
- Vavilov argues the extreme spin rates imply the two rocks are monolithic objects at least 30 times stronger than clay rather than loose rubble piles, meaning prevailing models of how asteroids have collided and reaccumulated over the solar system's 4.6-billion-year history may be wrong.
- Standing on the surface would mean moving at more than 100 km/h (60 mph), producing a "rollercoaster" sensation that would make clinging to the surface difficult, per Vavilov.
- The YORP effect — torque generated by uneven solar heating — is a candidate mechanism for spinning the asteroids up, yet remains uncertain because of their large distance from the sun, a point Vavilov called "another mystery."
Why it matters: Two multi-kilometer asteroids spinning every 5 minutes should fly apart if standard rubble-pile models hold, so the discovery forces planetary scientists to reconsider how collision histories are reconstructed over 4.6 billion years and raises the prospect that some large asteroids are pristine, monolithic relics from the solar system's formation rather than reassembled debris — a finding that hinges on just 2 unusual objects out of 9,000 surveyed and will require follow-up observations to confirm.
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