Mars is the fourth planet from the Sun, orbiting between Earth and the Asteroid Belt and Jupiter. It has been nicknamed "The Red Planet" because of its red color due to the rusted iron on its surface. It is the third smallest planet in the solar system after Pluto and Mercury. It was named after the Roman God of War. It has only 33% of gravity on Earth, this means an astronaut on Mars can jump higher than a human jumping on a trampoline on Earth. It has two moons named Deimos and Phobos, which unlike Earth's Moon, are shaped like a pair of potatoes and are very tiny. There are currently 7 man-made spacecrafts on or orbiting Mars. Five are orbiting around the planet, and two rovers on the surface. It is the second most known planet to humans after Earth. Mars is also similar to Earth in many ways; it has a similar axial tilt for seasons, polar ice caps, and a daily rotation that's only slightly slower. Mars is also home to the highest mountain and largest volcano in the solar system: Olympus Mons. It's as big as the state of Arizona and three times taller than Mount Everest, the tallest mountain on Earth. Mars has massive sandstorms that can last for months and cover most of the planet. Mars has ice water underneath its surface, which could hint that Mars used to have life on it Billions of years ago.