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

While observing an object called 8405 Asbolus, a 48-mile-wide (80-kilometer) chunk of ice and dust that lies between Saturn and Uranus, astronomers using NASA's Hubble Space Telescope were surprised to find that one side of the object looks like it has a fresh crater less than 10 million years old, exposing underlying ice that is apparently unlike any yet seen. This shows that these mysterious objects do not have a simple homogenous surface, say researchers.

Hubble didn't directly see the crater - the object is too small and far away - but a measure of its surface composition shows a complex chemistry.