SOLAR SYSTEM GUIDE
The solar system contains the Sun, eight planets, three dwarf planets, more than 100 moons, 250,000 known asteroids and 2000 known comets. At the centre of the solar system is a star named the Sun. Next are the four rocky inner planets: Mercury, Venus, Earth and Mars. Following are the four outer planets: Jupiter, Saturn, Uranus and Neptune mainly made of gas. One dwarf planet (1) Ceres is located between Mars and Jupiter while (134340) Pluto and (136199) Eris are at the edge of the solar system in the region known as the Kuiper Belt.
Between Mars and Jupiter is the asteroid belt containing rocky asteroids. Beyond Neptune is the Kuiper belt containing asteroids made from a mixture of ice and rock. Even further out, about 100,000 times further from the Sun than the Earth, is the Oort cloud, made from millions of frozen objects. The Oort cloud and the Kuiper belt are thought to be the places from which comets originate.
Our Earth is 150 million kilometres from the Sun, while Pluto is 40 times further away and Eris is almost 100 times further away. Such large distances between the Sun and each planet or dwarf planet make the solar system mostly empty space.
Remember, every star you see in the night sky marks the location of another system. In recent years astronomers have discovered over 200 new planets, called extra-solar planets or exoplanets, which orbit around various stars in the night sky.