Great Red Spot

Great Red Spot

. The largest and oldest known weather system in the solar system is Jupiterís Great Red Spot. The spot's diameter is twice that of Earth, and one-sixth the diameter of Jupiter itself. The red vortex swirls in the counterclockwise direction in Jupiterís southern hemisphere, showing that it is a high-pressure anti-cyclone. It has been observed for centuries, probably ever since astronomers turned the first telescopes toward the giant planet. Some small eddies are sucked into the Great Red Spot, helping to sustain it, while other eddies roll around the perimeter, probably reinforcing its circulation. A long-lived white oval is seen just below the Red Spot, also rotating in the anti-cyclone manner. This oval is one of three systems that formed in 1939. They had slowly contracted in length and drifted about the planet approaching and moving apart. The Voyager 1 spacecraft took this image on 25 February 1979. (Courtesy of NASA and JPL.)

Copyright 2010, Professor Kenneth R. Lang, Tufts University