GREAT RED SPOT
You could fit Earth into it 3 times. It resides between opposing jet streams in Jupiter's southern hemisphere. It is several degrees warmer than its surroundings. It spins counter-clockwise (except for the center, which spins slowly clockwise). It has existed for at least hundreds of years. It's darker red colored center and reason for being are not fully understood. My theory: a manifestation of magnetic energy perhaps related to its magnetic "tether" to the Sun.