|Location||Sol System IV|
|Temperature||-87 to -5°C|
|Distance from Sun||1.67 AU|
Until the first flyby of the planet by Mariner 4 in 1965, it was thought that Mars had channels of liquid water; it is now known that such channels do not exist. However, after Earth, Mars is the most likely planet in our solar system to harbour liquid water – and perhaps life. It is the only planet besides Earth that has seasons, and also has a rotational period nearly the same as Earth.
Mars has the highest mountain in the solar system, Olympus Mons, the largest canyon in the solar system, Valles Marineris, and polar ice caps. It has two moons, Phobos and Deimos, which are small and oddly-shaped and may be captured asteroids.
Mars in fiction
Fictional representations of Mars have been popular since the early 20th century. Interest in Mars has been stimulated by the planet's dramatic red colour, by early scientific speculations that its surface conditions might be capable of supporting life, and by the possibility that Mars could be colonised by humans in the future. Almost as popular as stories about Mars are stories about Martians engaging in activity (frequently invasions) away from their home planet.
- In Heredity (1941), a short story by Isaac Asimov, twin brothers who have been raised separately on Earth and Ganymede must work together to operate a Martian fungus farm.
- The Martian Chronicles (1950) by Ray Bradbury features human-like Martians with copper-coloured skin, human emotions and telepathic abilities. They have an advanced culture, but the human explorers are greeted with incomprehension and eventually the Martian civilisation is accidentally destroyed by human disease. Bradbury wrote many other short stories set on Mars.
- The Sands of Mars (1951) by Arthur C. Clarke involves a reporter who makes the long voyage to a desert Mars to write about the human colonists and along the way discovers there is life on Mars after all.
- The Martian Way (1952) by Isaac Asimov in which arrogant Earth people are scornful of the Martian colonists, who barely survive by salvaging "space junk", yet their way of life is what fits the Martian colonists for further space exploration, reaching Saturn first and eventually (Asimov implies) leading the way to the stars.
- The Outward Urge (1959) by John Wyndham describes a comparatively realistic Mars landing, without any Martians.
- In Larry Niven's harsh Known Space stories (1964- ) Mars is a backwater bypassed by humans in their rush to the mineral wealth of the Asteroid Belt.