Olympus Mons on Mars Is the Largest Volcano in the Solar System

Volcanoes are not unique to Earth, and the biggest one known is on another planet. NASA states that Mars is home to the largest volcano in the solar system, Olympus Mons, and that its base covers an area as large as the state of Arizona. A single mountain with a footprint the size of a large US state is hard to picture, which is why NASA uses the comparison. Mars holds a second record on the same NASA page. Valles Marineris, which NASA describes as the largest canyon in the solar system, extends about 2,400 miles, or 3,870 kilometers, in length. Together the two features give Mars both the largest volcano and the largest canyon known in the solar system.