Description
Mars is the fourth planet from the Sun in our solar system, orbiting the Sun in an orbit between Earth and Jupiter. The planet is smaller than Earth and, with a (maximum) magnitude of -2.9, less bright than Venus and usually less bright than Jupiter. Mars is sometimes called the red planet, but is actually more ochre-colored. The planet is named after the Roman god of war. Mars is easily visible with the naked eye, especially during the months around opposition. At night, Mars appears as a bright reddish "star," which, due to its relative proximity, is not a point source but a disk. Therefore, Mars does not twinkle like a distant red star like Aldebaran. Mars is a terrestrial planet with a thin atmosphere. In some places, its surface is dotted with impact craters, like the Moon's, while in other places, like Earth, volcanoes, valleys, sand dunes, and polar caps occur. Furthermore, the rotation period ("day") and the seasonal changes on Mars are similar to those on Earth. Before space exploration, it was often assumed that life and liquid water existed on Mars. After the Mariner 4 spacecraft flew past Mars in 1965, it was assumed that neither was possible. However, in 2003, the ESA Mars Express probe provided clarity on this matter, discovering water in the form of water vapor and ice. In 2008, the Phoenix spacecraft directly examined ice samples. Observations by the Mars Reconnaissance Orbiter may have detected flowing water during the warmest months on Mars. Mars has two moons, Phobos and Deimos, both small, irregularly shaped bodies. It has been hypothesized that these two moons are asteroids captured by Mars' gravity.
