Icy Mystery In Space

Centaur's bright surface spot could be crater of fresh ice.

The unexpectedly varied surface of a wayward piece of space debris has given astronomers new insights into the characteristics and behavior of centaurs, ghostly comet-like bodies that lie just beyond Pluto's orbit.

While using NASA's Hubble Space Telescope to observe Centaur 8405 Asbolus, a 48-mile-wide chunk of ice and dust that lies between Saturn and Uranus, astronomers were surprised to find that one side of the object looks like it has a fresh crater, less than 10 million years old.

The finding poses a mystery because the underlying ice exposed by the crater is unlike any yet seen, say researchers. "This shows that these mysterious objects do not have a simple homogenous surface," said a Hubble program spokesman.

Scientists using Hubble didn't directly observe the crater because it is too small and far away. Instead, its surface composition was determined by using the space telescope's near-infrared camera to determine the chemical composition of the ice.