Closer observations of Saturn’s tiny moons could give scientists a window into a tumultuous time in the early solar system. During that period, collisions were more common and the planets jostled for position, with Jupiter thought to have migrated from nearer the sun farther out to its current orbit. “That gives you additional information on the formation of the solar system,” Dr. Denk said.

Yet the irregular moons we are seeing so far may only be the beginning. “We estimated that there are potentially thousands,” around Saturn and Jupiter, Dr. Ashton said. Uranus and Neptune, too, may have many such irregular moons, but their vast distance from the sun makes them difficult to discover.

Saturn, despite being smaller than Jupiter, appears to have many more irregular moons. It may have three times as many as Jupiter, down to about two miles in size. The reason is unclear, Dr. Ashton said.

Jupiter’s original moons may have tended to be larger, and less likely to shatter. Or Saturn may have captured more objects into its orbit than Jupiter. Or Saturn’s moons may have been on orbits that were more likely to overlap and collide, producing smaller, irregular moons.