Center of the orthographic projection is at latitude 30 degrees N., longitude 150 degrees. The north polar residual ice cap, which is cut by spiral-patterned troughs and surrounded by the dark lowland plains of Vastitas Borealis, is located at the top. The right-central part is dominated by the Tharsis Montes volcanoes. The most prominent of the Tharsis Montes volcanoes is the largest known volcano in the solar system, Olympus Mons. The light-colored lowland plains of Amazonis, Elysium, and Arcadia Planitiae lies north and west of Olympus Mons. The heavily cratered highlands dominate the lower one-third.