Mars is smaller and less massive than Earth and has only 38% of Earth’s surface gravity. If you weigh 50 kg on Earth, Mars you’d weigh 19 kg on Mars. The solar system’s largest canyon Mars’ two moons is visible in the are shown photo at left here → as the dark with their horizontal correct sizes streaks near relative to the center the photo of right edge. Mars at right. Mars moon images Known as courtesy of NASA. Valles Marineris, this canyon is Mars has a thin atmosphere made mostly of carbon dioxide. Like Earth, Mars Mars has the 4000 km long, largest volcanoes 200 km wide and has clouds, storms, frost, and polar ice caps. Unlike Earth, Mars gets cold in the solar system. up to 7 km deep. Four of them are visible It would stretch from enough that some of the frost and ice is frozen carbon dioxide (dry ice), as the frost-covered circular NASA/JPL/Malin Space Science Systems Toronto to Vancouver not frozen water. Ice can be found in craters on Mars, and may even regions in the center of this photo if placed on Earth. taken by the Mars Global Surveyor spacecraft. form glaciers covered by a thin layer of Martian soil (above right). Mars has two small moons, Phobos and Deimos, which are probably captured asteroids. 1 Martian day (1 sol) Phobos (left) orbits Mars in less than one Martian day, which is bad news for it. Phobos’ = 24.6 Earth hours gravity raises tiny tides on Mars’ surface, but Phobos moves so fast in its orbit that the 1 Martian year tidal bulge on the side of Mars nearest Phobos lags behind it. Phobos is pulled backwards = 687 Earth days and slowed down by the gravity of this tidal bulge. As Phobos slows down, it moves NASA/JPL/ closer to Mars. Eventually, Phobos will crash into Mars and leave a large crater behind. University of Arizona There is no liquid water on the surface of Mars today, but there is water ice on and under the surface. Patches of water ice were seen underneath the Phoenix spacecraft (left) after it landed on Mars in 2008. Phoenix also carried a Canadian weather station which York University researchers were in charge of overseeing. NASA/JPL/University of Arizona image mosaiced and color-coded for Aviation Mars is shown above with Week & Space Technology by Kenneth Kremer and Marco Di Lorenzo. its correct relative size to the Sun (the yellow circle) in this scale model..