The first triple asteroid near Earth has been discovered.
It was originally found in 2001, but new observations with the radar telescope at the Arecibo Observatory in Puerto Rico reveal it is three gravitationally bound rocks.
"This discovery has extremely important implications for ideas about the origins of near-Earth asteroids and the processes responsible for their physical properties," said Cornell University and Arecibo astronomer Michael C. Nolan. "Double, or binary, asteroid systems are known to be fairly common — about one in six near-Earth asteroids is a binary — but this is the first near-Earth triple system to be discovered."
Nolan said this finding prompts several questions: Are the objects orbiting in the same plane? How rapidly are the orbits changing with time? Did the smaller objects, which Nolan calls moons, form when this asteroid system formed in the main asteroid belt, or after it arrived in near-Earth space?