杏吧原创

MOST of the dozen small moons discovered around Saturn last year are debris
from cometary impacts, says a team led by Brett Gladman of the C么te d鈥橝zur
Observatory in Nice. The moons all have large irregular orbits. The team grouped
them according to the inclinations of their orbits to Saturn鈥檚 orbit (
Nature, vol 412, p 163). Gladman thinks two groups are the remains of
larger objects captured by Saturn鈥檚 gravity but later shattered by comets. A
third group were fragments from impacts with the 220-kilometre moon, Phoebe.