Mars

Mars is the fourth planet from the Sun and lies beyond Earth. It is the second smallest planet in the solar system after Mercury. Its surface is covered in iron oxide, which gives it a rusty red appearance visible in the night sky.

Mars is a rocky, arid planet. It has a very thin atmosphere composed mainly of carbon dioxide. The atmospheric pressure is far lower than Earth's, so liquid water cannot persist on the surface. Temperatures are extremely cold.

Surface features

Mars contains massive volcanic mountains, the largest of which is Olympus Mons, counted among the highest mountains in the solar system. It also has deep canyons, including the Valles Marineris system. Both poles have deposits of ice consisting of frozen water and frozen carbon dioxide; their extent changes with the seasons.

Orbit and moons

A Martian day is similar to an Earth day, though slightly longer. Its year, the time it takes to orbit the Sun, is close to two Earth years. Mars has two small moons that do not orbit in regular patterns: Phobos and Deimos.

Exploration

Mars is the most explored planet by unmanned probes. Three types of missions have been used: flybys, orbiters, and landers including rovers. Research aims include determining whether water existed in the past and searching for signs of past life. No confirmed evidence of life on Mars has been found to date.