Before any spacecraft visited Mars, Tharsis was the name given to a prominent albedo marking on the surface. Mariner 9 photographed the planet in 1971 and we learned that Tharsis is a volcanic plato. There are 12 large volcanoes in the region including the famous Olympus Mons which is the tallest volcano in the solar system and Alba Patera which is the largest volcano in the solar system in terms of areal extent. All the volcanoes in Tharsis region are now collectively known as Tharsis Montes and the name Tharsis was given to one of the lesser volcanoes, Tharsis Tholus. Although small by Mars standards Tharsis Tholus would be a giant on earth with its diameter of about 120 kilometers. According to crater counts it has not been active during the last 2 billion years.
This animation is Copyrighted © 1997 by A. Tayfun Oner. Any commercial/for-profit use needs to be addressed to Calvin J. Hamilton.