As impressive as the highest peaks on Earth are, they barely compare to the tallest mountains in our solar system. Namely, Olympus Mons is a giant volcano on Mars that towers 16 miles above the neighboring plains and stretches 374 miles. It is so broad that it doesn’t look like a typical mountain found on Earth. If you were standing on it, it would simply appear like a soft slope. To better understand how tall it is, Olympus Mons is three times as high as Mount Everest (5.5 miles) roughly the same size as the state of Arizona, and as wide as France. It is even much bigger than Hawaii’s Mauna Loa, the tallest volcano on Earth, which rises 6.3 miles above the sea floor (and 2.6 miles above sea level).
Located in the Tharsis Montes region near the Martian equator, Olympus Mons is a shield volcano. This means that rather than fiercely ejecting molten material, it was created by lava slowly flowing down its sides. Due to this, the mountain has an almost flat appearance, with an average slope of only 2º to 5º. Olympus Mons’ shape results from many thousands of highly fluid, basaltic lava flows. At its summit, there is a 53-mile diameter crater, or caldera, comprising several mutually intersecting craters. Its size has long been attributed to the stability of the Martian crust and to a long accumulation time, possibly having taken billions of years to form. However, some mountain regions may be only a few million years old. This indicates a chance that it’s still an active volcano that could erupt at some point. Scientists think it could have stayed volcanically active for hundreds of millions of years, meaning it’s been active far longer than any volcano on Earth.
