Scientists have found a new moon hidden in one of Saturn's dazzling outer rings. The international Cassini spacecraft spotted the moon, which measures about a third of a mile wide. The discovery was announced Tuesday in a notice by the International Astronomical Union. Researchers have long puzzled over the formation of Saturn's G ring, one of the planet's more mysterious arcs. They now think the G ring was likely formed from icy debris that scattered when meteorites crash into the newfound moon.