Jupiter and Saturn : Revised Edition

Jupiter and Saturn are the two largest planets in the solar system and the first two gas giant planets encountered when moving away from the Sun.

They are both immensely complicated systems not unlike miniature solar systems on their own: Jupiter has 63 known moons and its own ring system, whereas Saturn is famous for its rings and 62 known moons.

Astronomers are finding with some regularity new, distant moons orbiting each of these planets, so their number of known satellites continues to grow.