Which planet is known as the Red Planet?

Mars is known as the Red Planet because iron-bearing minerals in its surface dust and rocks oxidize, or rust, producing its distinctive orange-red appearance.

Mars is the fourth planet from the Sun and is a rocky world with a thin atmosphere made mostly of carbon dioxide. Fine dust is widespread across the planet and can be lifted by winds, sometimes forming enormous dust storms. From Earth, this dusty surface gives Mars its reddish color even when viewed without a telescope.

The planet’s red appearance has been noticed for thousands of years. Ancient sky-watchers associated its striking color with blood and war; the Romans connected it with Mars, their god of war. That name remains in use today, and it also influenced the naming of the planet’s two moons, Phobos and Deimos, after figures associated with the war god in Greek mythology.

Mars is not uniformly red. Its surface also includes dark volcanic rock, pale dust, ice caps, craters, valleys, and enormous volcanoes. Olympus Mons, the tallest known volcano in the Solar System, stands on Mars.