Asteroid-like body appears to have rings

Artist's conception of Chariklo's rings.

Lucie Maquet

Centaurs are one of the mythical creatures invented by combining two organisms you wouldn’t regard as similar—in this case, parking a human torso on a horse’s shoulders. A group of oddball objects in our Solar System in orbit beyond the asteroid belt have earned the name “Centaur” because they're a bit like asteroids and a bit like comets. Recent observations of one of them show that it lives up to the spirit of the name in another way as well. It’s sporting a rakish accessory you probably associate with planets—rings.

Each of the gas giants in our Solar System—Jupiter, Saturn, Neptune, and Uranus—has rings, though only Saturn’s are visually prominent. Rings, which are made of many small chunks of ice or rock, can form when a moon comes too close to its host. The difference in gravitational pull from one side of the moon to the other can actually rip it apart. Rings can also form from other sources of material, like collisions between moons, or even particles ejected by moons like Saturn’s ice-spewing Enceladus.

At about 250 kilometers wide, “Chariklo” is the largest of the Centaurs. It orbits the Sun at a distance between Saturn and Uranus, but astronomers think it may have been brought in from an orbit beyond Neptune less than ten million years ago.