Extinct Martian Volcano Dwarfs Everest

This image, taken by the camera on the Mars Global Surveyor, shows the martian volcano Arsia Mons on the right of the frame. Towering some 30,000 feet (9 kilometers) above the surrounding plains, Arsia Mons is one of the largest volcanoes known. The volcano’s summit — a large crater called a caldera — is approximately 68 miles (110 kilometers) across.