Geography of Mars Aurorae Sinus. The largest dark feature seen from Earth is Syrtis Major Planum. The shield volcano, Olympus Mons ("Mount Olympus"), rises 22 km above the surrounding volcanic plains, and is the highest known mountain on any planet in the solar system. It is in a vast upland region called Tharsis, which contains several large volcanos. See list of mountains on Mars. The Tharsis region of Mars also has the solar system's largest canyon system, Valles Marineris or the "Mariner Valley", which is 4,000 km long and 7 km deep. Mars is also scarred by countless impact craters. The largest of
Ahuna Mons Ahuna Mons Ahuna Mons is the largest mountain on the dwarf planet and asteroid Ceres. It protrudes above otherwise smooth terrain, it is not an impact feature, and it appears to be the only mountain of its kind on Ceres. Bright streaks run top to bottom on its slopes; these streaks are thought to be salt, similar to the better known Cererian bright spots, and likely resulted from cryovolcanic activity from Ceres's interior. It is named after the traditional post-harvest festival "Ahuna" of the Sumi Naga people of India. In July 2018, NASA released a comparison of physical features, including