The reddish iron oxide prevalent on its surface gives Mars a reddish appearance.

Mars was the most prominent of the military gods in the religion of the Roman army.

A Martian year is 687 Earth days.

The term sol is used by planetary scientists to refer to the duration of a solar day on Mars. The term was adopted during the Viking project in order to avoid confusion with an Earth day.

The Martian atmosphere consists of approximately 96% carbon dioxide, 1.9% argon, 1.9% nitrogen, and traces of free oxygen, carbon monoxide, water and methane.

Mars is the site of Olympus Mons, the largest volcano and second-highest known mountain in the Solar System (next to Rheasilvia central peak on the asteroid Vesta).

NASA's Mariner 4 captured the first images of another planet ever returned from deep space; their depiction of a cratered, seemingly dead world, largely changed the scientific community's view of life on Mars.

Dust in the Martian atmosphere has fine particles that permit blue light to penetrate the atmosphere more efficiently than longer-wavelength colors.

Copernicus was the first astronomer to postulate that Mars and a few other bodies known at the time were planets. The heliocentric theory that he published in 1543 marked the first time that astronomers widely considered the possibility that the Sun was the center of the Solar System instead of the Earth.

Although NASA scientists quickly determined that the face was created by tricks of light and shadows, some people believed that the face was the remnant of an alien civilization, suggesting that other rocky outcroppings in the area might be a crumbling extraterrestrial city. Other high resolution images subsequently confirmed that the face is an optical illusion revealed only as the light hits the surface and wells of the rocks at specific angles.