Mars is the fourth planet from the Sun and is often called the "Red Planet" because the iron oxide (rust) on its surface gives it a reddish appearance. It is a dusty, cold, desert world with a very thin atmosphere.
Even though it is much colder than Earth, Mars has seasons, polar ice caps, volcanoes, canyons, and weather. It is home to Olympus Mons, the largest volcano and highest known mountain in our entire solar system!
Because it is so close to us and made of rock, scientists have sent many rovers and orbiters to study Mars, hoping to discover if life ever existed there billions of years ago.