Inner Planets

MERCURY

• Mercury is the closest planet to the sun, so it naturally gathers heat, although its dark side can still get cold. Mercury can orbit the sun in 88 days. A day on Mercury is equal to 59 Earth days. It is also one of the two planets in the solar system that doesn't have any moons.

VENUS

• Venus is the next planet in the solar system. Its atmosphere traps heat, therefore it is the hottest planet. Because Venus is shrouded in acidic clouds, it's very difficult to see the surface from Earth. Venus, like Mercury, has no moons.

MARS

• Mars is the fourth planet, after Earth. It has two moons, Phobos and Deimos. Its thin atmosphere is composed mostly of carbon dioxide. On the surface of Mars lies the largest volcano in the solar system, Olympus Mons- a staggering 27 kilometres tall, the base of the volcano is about the size of the state Arizona. Due to iron oxide, Mars appears red.

ASTEROIDS

• Asteroids are rocky bodies that orbit the Asteroid Belt between Mars and Jupiter. Some also orbit the sun. Asteroids are relatively small, but some can be quite large- the largest Asteroid recorded, Ceres, is 945 kilometres in diameter.