By way of comparison, here on Earth, Mount Everest stands approximately 8.8km above sea level, while the world\u2019s tallest volcano, Chile\u2019s Nevados Ojos del Salado, stands just 6.8km high.<\/p> And Olympus Mons isn\u2019t just tall \u2013 it\u2019s broad, too.<\/p> In fact, it has a surface area of some 300,000\u00a0km2<\/sup>\u00a0(120,000\u00a0sq\u00a0mi) \u2013 that\u2019s roughly the size of Poland or Italy!<\/p> That\u2019s because, like the volcanoes that make up the islands of Hawaii, Olympus Mons is a shield volcano.<\/p> This means it has broader, flatter profile \u2013\u00a0 like a warrior\u2019s shield lying on the ground \u2013 than the cinder cone, lava cone or lava dome types that probably spring more immediately to mind when you hear the word \u2018volcano\u2019.<\/p> Shield volcanos form when a fissure in the planetary surface oozes very fluid, low-viscosity lava, which tends to spread out further and more quickly than the more viscous lava associated with other types of volcano.<\/p> Olympus Mons lies at the heart of a region of volcanic activity called Tharsis Rise.<\/p> This activity is caused not by the movement of tectonic plates \u2013 Mars is too small to have those \u2013 but rather by the presence, just below the surface, of a huge magma hotspot.<\/p> It is this that has enabled the volcano to reach its enormous size.<\/p> Since its vulcanism isn\u2019t subject to fluctuations over time (as a result of plate tectonics), layers of lava have been able to build up in one place over millions of years \u2013 although for the past 25 million years or so, this Martian volcano has lain dormant.<\/p> The Martian volcano is visible from Earth through a telescope as an albedo feature \u2013 an area of brightness\u00a0\u2013 that was traditionally labelled Nix Olympica\u00a0(Latin for ‘Olympic Snow’).<\/p> Astronomers had long suspected this to be a mountainous region, but it wasn\u2019t until NASA\u2019s Mariner 9<\/a> spacecraft confirmed that topography in 1971, that Olympus Mons was given its current name.<\/p> In Latin, the name means ‘Mount Olympus’.<\/p>Not just tall, but large<\/strong><\/h2>
![\"Image](\"https:\/\/c02.purpledshub.com\/uploads\/sites\/48\/2024\/07\/olympus-mons-mars-express-1024x648.jpg?fit=800%2C506\")
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Why so big?<\/strong><\/h2>
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