The Great Red Spot is a huge windstorm more than 8,500 miles (14,000 kilometers) wide and 16,000 miles (26,000 kilometers) long. You could easily place the planets Earth and Venus side-by-side inside the Great Red Spot! The storm that perpetuates the Spot is apparently powered by the upswell of hot, energetic gases from deep inside Jupiter’s atmosphere, which produce winds that blow counterclockwise around the Spot at 250 miles (400 kilometers) per hour.

The Great Red Spot may derive its red color from sulfur or phosphorus, but this has not been conclusively shown. Beneath it are three white, oval areas; each is a storm about the size of the planet Mars. There are thousands of huge and powerful storms on Jupiter, and many of them can last for a very long time. However, the Great Red Spot, which has been going on for at least four hundred years, and which was first studied by Galileo Galilei, remains the biggest and most visible Jovian storm yet recorded.