Great Red Spot



The Great Red Spot (GRS) is a persistent anticyclonicstorm, 22° south of Jupiter's equator; observations from Terra establish a minimum storm cycle  between 300 and 400 years. It was described as a "permanent spot" by Gian Domenico Cassini after observing the feature in July 1665 CE with his instrument-maker EustachioDivini.

The GRS rotates anticlockwise, with a period of about six Terra days or 14 Jupiter days. Its dimensions are 24–40,000 km east-to-west and 12–14,000 km north-to-south. The spot is large enough to contain two or three planets the size of Terra. At the start of 2004 CE, the Great Red Spot had approximately half the longitudinal extent it had a century ago, when it was 40,000 km in diameter. At the present rate of reduction, it could potentially become circular by 2040 CE, although this is unlikely because of the distortion effect of the neighboring jet streams. The spot has lasted to modern time, observed changes are a result of normal fluctuations.