Glossary term: Great Red Spot

Description: The Great Red Spot is a gigantic anticyclonic storm in the atmosphere of Jupiter located at 22 degrees south of its equator. About 15,000 kilometers (km) long and nearly 12,000 km wide, it is currently a little larger than Earth, although it has reached much larger dimensions in the past. Winds within the Great Red Spot can reach more than 400 kilometers per hour (km/h) (250 miles per hour (mph)). The reason for its red color is currently unknown although there are several competing hypotheses. A large red spot on Jupiter was discovered by the astronomer Giovanni Cassini in 1665 and was observed for half a century. However there is a century-long gap in observations so it is not known if this spot is the same feature as the one seen for the last two hundred years.

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Term and definition status: This term and its definition have been approved by a research astronomer and a teacher

The OAE Multilingual Glossary is a project of the IAU Office of Astronomy for Education (OAE) in collaboration with the IAU Office of Astronomy Outreach (OAO). The terms and definitions were chosen, written and reviewed by a collective effort from the OAE, the OAE Centers and Nodes, the OAE National Astronomy Education Coordinators (NAECs) and other volunteers. You can find a full list of credits here. All glossary terms and their definitions are released under a Creative Commons CC BY-4.0 license and should be credited to "IAU OAE".

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The planet Jupiter with horizontal cloud ribbons and the great red spot


Caption: This full disk view of Jupiter was obtained on 21 April 2014 with Hubble's Wide Field Camera 3 (WFC3). It shows the prominent great red spot, a gigantic cyclone. Cloud ribbons cover the surface, whose colours stem from gases like ammonia and other chemical compounds.
Credit: NASA, ESA, and A. Simon (Goddard Space Flight Center) credit link

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