Mars is entitled after the very old Roman god of war, as befitting the red planet's bloody color. The Romans copied the very old Greeks, who named the fourth planet from the sun after their god of war, Ares. Other civilizations also normally provided the planet titles based on its hue — for demonstration, the Egyptians named it "Her Desher," meaning "the red one," while very old Chinese astronomers dubbed it "the fire star."

Physical Characteristics of the Planet Mars

Regolith

The brilliant rust hue Mars is renowned for is due to to iron-rich minerals in its regolith — the loose dirt and rock covering its exterior. The dirt of Earth is a kind of regolith, albeit one laden with organic content. 

Geology

The cold, thin atmosphere means liquid water currently cannot exist on the Martian surface for any length of time. This means that although this desert planet is just half the diameter of Earth, they have the same amount of dry land.

The red planet is home to both the highest mountain and the deepest, longest valley in the solar system. Olympus Mons is roughly 17 miles (27 kilometers) high, about three times as tall as Mount Everest, while the Valles Marineris system of valleys — named after the Mariner 9 probe that discovered it in 1971 — can go as deep as 6 miles (10 kilometers) and runs east-west for roughly 2,500 miles (4,000 kilometers), about one-fifth of the distance around Mars and close to the width of Australia or the distance from Philadelphia to San Diego.