Jupiter’s Great Red Spot May Soon Be a Great Red Memory

SCIENCE

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Discussion Ideas

Jupiter’s Great Red Spot is growing less great. What is the Great Red Spot? Browse our informative activity for some help.
- Jupiter’s Great Red Spot is a great big storm. Specifically, it’s an anticyclone, a weather system in which air typically rotates around a center of a high pressure. Anticyclones like the Great Red Spot rotate counterclockwise in their planet’s Southern Hemisphere.
- The Great Red Spot is about 1.3 times the size of Earth, and rotates at speeds between 430 and 680 kilometers per hour (270 and 425 miles per hour)—although winds in the center of the storm barely move at all.
- The Great Red Spot was probably first observed and reported in the 1600s, although it had likely been spinning for dozens if not hundreds of years before that.
- NASA’s Juno spacecraft got up close to the Great Red spot last year—about 3,400 kilometers (2,100 miles) above the violently swirling clouds. Juno stared directly at the storm for 12 minutes.

Why has the Great Red Spot been so long-lasting?
- The storm is caught between Jupiter’s racing belts and zones.
  - Belts are dark bands of clouds, generally thin and located at fairly low altitudes.
  - Zones are light bands of clouds, generally thicker than belts and located at high altitudes. Zones have lighter colors than belts due to a higher concentration of ammonia and light-reflecting ammonia ice.
- “Think of the GRS [Great Red Spot] as a spinning wheel that keeps on spinning because it’s caught between two conveyor belts that are moving in opposite directions. The GRS is stable and long-lived, because it’s ‘wedged’ between two jet streams that are moving in opposite directions.”

Why is the Great Red Spot shrinking?
- Good question. It’s a planetary puzzle scientists haven’t solved yet.
  - “That the storm now appears to be shrinking makes little sense, as it should gain more girth and power by continually gobbling up other storms around it … It’s ingesting smaller vortices — think of the Great Red Spot as a vampire eating smaller storms.”
  - Some scientists think that “although the Great Red Spot is still consuming storms, there might not be as many storms around to eat. Or the storms might not be spinning as rapidly, so they don’t provide the great crimson spot with the energy it needs to sustain itself.”