Mars is the last rock planet in our solar system. It is half the size of Earth and has a very thin atmosphere. Because Mars is further from the sun, the temperature is from -60 C to around freezing point. Mars does have polar ice caps and the highest mountain in the solar system Mont Olympus (25 km high, 3 times higher than Mount Everest). Mars has two tiny moons Phobus and Deimos that will fall apart in the future and give Mars a ring.