Jupiter’s Great Red Spot (GRS) is an atmospheric storm that has been raging in Jupiter’s southern Hemisphere for at least 400 years. Many believe that Giovanni Cassini was the first to observe it in the late 1600s, but scientists doubt that it had just formed at that time. About 100 years ago, the storm covered over 40,000 km of the surface. It is currently about one half of that size and seems to be shrinking. At the present rate that it is shrinking it could become circular by 2040. Scientists doubt that this will happen because of the distortion effect of neighboring jet streams. It is not known how long the spot will last, or whether the changes in size are a result of normal fluctuations.