On Wednesday (March 26), astronomers announced the historic discovery of a ring system around asteroid Chariklo, the largest Centaur asteroid that orbits between Saturn and Uranus in the outer solar system. In this artist's impression, the surface features of the asteroid can be seen with one of the dusty rings blocking the view.
Until now, ring systems have only been seen around Jupiter, Saturn, Uranus and Neptune -- this is the first small celestial body found possessing such a ring system and is indicative of an asteroid collision.
As seen from the asteroid's surface, the ring system would appear pretty dramatic when relecting the weak solar light. The 20 kilometer-wide ring system is 1000 times closer than the moon is to the Earth.
The ring system was discovered as the asteroid drifted in front of a distant star, blocking its light from view. This event is known as an occultation and astronomers got more than they bargained for during this particular celestial dance. As predicted, the asteroid blocked light from the star for a few seconds, but just before and just after the event, there was a slight and unexpected dip in starlight brightness. These extra dips have been interpreted as the presence of a dusty ring system around asteroid Chariklo -- an unprecedented find.
The occultation was predicted and observed by the MPG/ESO 2.2-meter telescope at the ESO's La Silla Observatory. To gain the most detail of the occulation, many South American telescopes participated in the observational campaign.