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This image, taken by Voyager 1 on March 1, 1979, shows Jupiter's Great Red Spot, a tremendous atmospheric storm. It rotates counterclockwise, once every six days, and is large enough to hold several Earths. Jupiter's deep, layered atmosphere is made of hydrogen and helium.

Voyager 1 and 2 were launched in March and July of 1979. The Grand Tour was designed to explore Jupiter, Saturn, Uranus and Neptune. The spacecraft trajectories took advantage of an alignment of the planets which occurs once every 175 years, utilizing gravity assist to reduce the need for large onboard propulsion systems.