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Olympus Mons

Large volcano on Mars, the largest known volcano in the solar system. It consists of a central structure that ascends about 13 mi (21 km) above Mars's mean radius and is 335 mi (540 km) wide at the base; it is surrounded by an outward-facing cliff rising as much 6 mi (10 km) above the surrounding area. At the summit is a crater 53 mi (85 km) in diameter. For comparison, Earth's largest volcano, Mauna Loa, is 75 mi (120 km) wide at the base and rises 5.6 mi (9 km) above the ocean floor.

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