The smallest and most distant of the "gas giant" planets. Neptune has much in common with its three huge neighbors Jupiter, Saturn, and Uranus. It has strong winds, several light and dark spots on its surface, an internal heat source, rings, and moons. Neptune's Great Dark Spot is a storm about the size of the Earth.

Image credits: main image, courtesy of JPL, California Institute of Technology and NASA; Frank Summers: AMNH.