Mars this, there are far fewer craters on Mars compared with the Moon, because the atmosphere of Mars provides protection against small meteors and surface modifying processes have erased some craters. Martian craters can have a morphology that suggests the ground became wet after the meteor impacted. The shield volcano Olympus Mons ("Mount Olympus") is an extinct volcano in the vast upland region Tharsis, which contains several other large volcanoes. Olympus Mons is roughly three times the height of Mount Everest, which in comparison stands at just over . It is either the tallest or second-tallest mountain in the Solar System,
Solar System all have impact craters and tectonic surface features, such as rift valleys and volcanoes. The term "inner planet" should not be confused with "inferior planet", which designates those planets that are closer to the Sun than Earth is (i.e. Mercury and Venus). Asteroids except for the largest, Ceres, are classified as small Solar System bodies and are composed mainly of refractory rocky and metallic minerals, with some ice. They range from a few metres to hundreds of kilometres in size. Asteroids smaller than one meter are usually called meteoroids and micrometeoroids (grain-sized), depending on different, somewhat arbitrary definitions. The asteroid