Mars, the mysterious red ball 141,637,725 miles (227,943,824 km) from the sun, is a desolate rock that may have once held rivers of flowing water. The Red Planet possesses stark landscapes featuring both the highest mountain and the deepest, longest valley in the solar system. Its radius is about 2,106.1 miles (3,389.5 km).
Mars is much colder than Earth, largely due to its greater distance from the sun. The average temperature hovers around a frosty minus 80 degrees F (minus 60 degrees C). Channels, valleys, and gullies cut into the entire surface of Mars, and suggest that liquid water might have flowed across the planet's surface. Let's go there next!