The Great Red Spot of Jupiter is a massive anticyclonic storm that is large enough to contain two or three Earth-sized planets. The storm has lasted at least 340 years and is large enough to be seen through Earth-based telescopes.
The Great Red Spot is the most powerful storm in the solar system. It is thought to have been first observed by the astronomer Cassini, who described the storm as early as 1665. Observations of the storm over the centuries have revealed that it is gradually losing strength and shrinking, having lost more than half its size since the late 1800s.