What is Jupiters “red spot”?
The Great Red Spot is a persistent anticyclonic storm on the planet Jupiter, 22° south of the equator, which has lasted for at least 178 years and possibly as long as 343 years or more. The storm is large enough to be visible through Earth-based telescopes. It was probably first observed by Giovanni Domenico Cassini, who described it around 1665. The spot has been noticeably red at times throughout its observed history, yet has not been appreciably red in the visible spectrum since a rather brief period in the mid 1970s. Storms such as this are not uncommon within the turbulent atmospheres of gas giants. Jupiter also has white ovals and brown ovals, which are lesser unnamed storms. White ovals tend to consist of relatively cool clouds within the upper atmosphere. Brown ovals are warmer and located within the “normal cloud layer”. Such storms can last hours or centuries. Before the Voyager missions, astronomers were highly uncertain of the Red Spot’s nature. Many believed it to be a sol
The Great Red Spot is a great anti-cyclonic (high pressure) storm akin to a hurricane on Earth, but it is enormous (three Earths would fit within its boundaries) and it has persisted for at least the 400 years that humans have observed it through telescopes. Since it is anti-cyclonic in Jupiter’s Southern hemisphere, the rotation is counterclockwise, with a period of about 6 days. (A hurricane in Earth’s Southern hemisphere rotates clockwise because it is a low pressure system.) The clouds associated with the Spot appear to be about 8 km above neighboring cloud tops. The following two figures show a recent Galileo view of the Great Red Spot, and a closeup of the turbulence in its vicinity. The Coriolis effects that are responsible for cyclones and anti-cyclones on Earth are greatly magnified on Jupiter, which has a rotational frequency about 2 1/2 times that of Earth, but this alone would not account for the persistence and size of the Great Red Spot. There are other features similar t
