Authors : Timeea , Muhammet , Ahmet Bugra , Elli and Edgaras
Mars : What we know about the Red Planet
Mars is the fourth planet from the sun . Befitting the Red Planet ' s bloody color , the Romans named it after their god of war . In truth , the Romans copied the ancient Greeks , who also named the planet after their god of war , Ares . Other civilizations also typically gave the planet names based on its color — for example , the Egyptians named it " Her Desher ," meaning " the red one ," while ancient Chinese astronomers dubbed it " the fire star ." The bright rust color Mars is known for is due to iron-rich minerals in its regolith — the loose dust and rock covering its surface . The soil of Earth is a kind of regolith , too , albeit one loaded with organic content . According to NASA , the iron minerals oxidize , or rust , causing the soil to look red . 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 — reaches as deep as 6 miles ( 10 km ) and runs east-west for roughly 2,500 miles ( 4,000 km ), about one-fifth of the distance around Mars and close to the width of Australia .