Two large asteroids found spinning as fast as a fairground ride
New Scientist 2026-10-09 17:00:00
Context: Dmitrii Vavilov at the University of Washington in Seattle and his colleagues have analysed data from the Vera C. Rubin Observatory in Chile to study the rotation of asteroids. The team measured the rotation of 260 asteroids from a sample of over 9000 and identified two large asteroids in the asteroid belt between Mars and Jupiter that are spinning extremely fast. These asteroids are challenging existing models of asteroid formation and composition.
Key Facts
- Two large asteroids, each over 2 kilometres wide, were found to complete a full spin every 5 minutes, a rotation speed that is unprecedented for asteroids of their size.
- 66 asteroids out of 260 studied were deemed super-fast rotators, spinning quickly enough to complete a rotation in less than 2.2 hours, a limit at which asteroids should no longer be able to hold themselves together under their own gravity.
- The high rotation speed of the two large asteroids suggests that they are monolithic objects at least 30 times stronger than clay, rather than loose conglomerations of material known as rubble piles.
- The asteroids' fast spin may have been caused by the sun heating their surfaces and giving them torque, known as the YORP effect, although this is uncertain due to their large distance from the sun.