Gas giant planets. Artwork comparing the four gas giant planets which lie in the outer solar system. The planets are (from top to bottom): Neptune, Saturn, Jupiter and Uranus. Their relative posit- ions in the solar system are (innermost to outer- most): Jupiter, Saturn, Uranus, Neptune. Gas giant planets are made of the light gases hydrogen and helium, with some trace chemicals. They have no definite solid surface but their constituent gases may form liquid and solid areas deep within the planet because of the intense pressure. Their rings are largely made of ice and dust grains. Gas giants lie in the outer solar system, and are much heavier than the inner planets such as Earth.