Olympus Mons orbit around Mars in 1971 during a global dust-storm. The first objects to become visible as the dust began to settle, the tops of the Tharsis volcanoes, demonstrated that the altitude of these features greatly exceeded that of any mountain found on Earth, as astronomers expected. Observations of the planet from Mariner 9 confirmed that Nix Olympica was a volcano. Ultimately, astronomers adopted the name "Olympus Mons" for the albedo feature known as Nix Olympica. Olympus Mons is located between the northwestern edge of the Tharsis region and the eastern edge of Amazonis Planitia. It stands about from the other
Tharsis Montes is about across and stands above the ocean floor. The Tharsis Montes volcanoes lie near the equator, along the crest of a vast volcanic plateau called the Tharsis region or Tharsis bulge. The Tharsis region is thousands of kilometers across and averages nearly above the mean elevation of the planet. Olympus Mons, the tallest known mountain in the Solar System, is located about northwest of the Tharsis Montes, at the edge of the Tharsis region. The Tharsis Montes were discovered by the Mariner 9 spacecraft in 1971. They were among the few surface features visible as the spacecraft entered orbit