Jupiter, Saturn, Neptune, and Uranus—the “gas giants” of our solar system—are composed of cores of ice and rock larger than Earth that are covered with thick atmospheres of hydrogen and helium and buried under immense oceans of liquefied hydrogen and helium thousands of miles deep. None of these planets have any real “surfaces” in the normal sense of the word—only mushy regions where gases become compressed into liquids and where liquids become compressed into solids, all of which are hidden in total and perpetual darkness.
