Jupiter's Great Red Spot. 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.)
This is a reprocessed image of Jupiter’s Great Red Spot from the 1979 Voyager 1 encounter with the planet. Old data like this is being crunched by people like Bjorn Jonsson to create new and better detailed images that were not possible when the data sets were originally acquired.
The Great Red Spot of Jupiter, as seen from the Voyager 1 spacecraft, a gigantic hurricane-like storm system that has been raging for over 300-years, and perhaps much longer. Three Earths could fit inside it.