Mars is the fourth planet from the Sun and the second-smallest planet with a thin atmosphere, having the surface features reminiscent both of the impact craters of the Moon, and the valleys, deserts and polar ice caps of Earth. It is the most widely searched planet for life.

It is hypothesized that the Solar System formed from a giant rotating ball of gas and dust known as the pre-solar nebula. Much of it formed the Sun while more of its dust went on and merged to create the first proto-planets. Mars was one of these planets and after the gravity pulled enough swirling gas and dust, it became the fourth planet from the Sun.

Mars has a relatively pronounced orbital eccentricity of about 0.09. Of the seven other planets in the Solar System, only Mercury has a larger orbital eccentricity. It is known that in the past, Mars had a much more circular orbit. At one point, 1.35 million Earth years ago, Mars had an eccentricity of roughly 0.002, much less than that of Earth today. It is believed that the closest distance between Earth and Mars will continue to mildly decrease for the next 25.000 years.

Mars Facts