Outer planet

Outer planets

The four outer planets, called giant planets or Jovian planets, collectively make up 99% of the mass orbiting the Sun. All four giant planets have multiple moons and a ring system, although only Saturn's rings are easily observed from Earth. Jupiter and Saturn are composed mainly of gases with extremely low melting points, such as hydrogen, helium, and neon, hence their designation as gas giants. Uranus and Neptune are ice giants, meaning they are largely composed of 'ice' in the astronomical sense (chemical compounds with melting points of up to a few hundred kelvins such as water, methane, ammonia, hydrogen sulfide, and carbon dioxide.) Icy substances comprise the majority of the satellites of the giant planets and small objects that lie beyond Neptune's orbit.