What is the Great Red Spot on Jupiter?

The Great Red Spot is a giant, spinning storm in Jupiter's atmosphere. It is like a hurricane on Earth, but it is much larger. Jupiter's Great Red Spot is more than twice the size of Earth! Winds inside this storm reach speeds of about 270 miles per hour. Nobody knows when the Great Red Spot first appeared on Jupiter, but it has been seen on Jupiter ever since people started looking through telescopes about 400 years ago.