Our Solar System consists of eight planets which orbit the Sun and is approximately 4.6 billion years old. The four small inner planets are “terrestial planets” and are Mercury, Venus, earth and Mars while the four outer planets are “Gas Giants, Jupiter, Saturn, Uranus and Neptune.
All planets have almost circular orbits that lie within a nearly flat disc called the “ecliptic plane”.
The Solar System also contains a number of regions populated by smaller objects. The asteroid belt, which lies between Mars and Jupiter, is similar to the terrestrial planets as it mostly contains objects composed of rock and metal.
COMETS
Comets are small Solar System bodies,typically only a few kilometres across, composed largely of volatile ices. They have highly eccentric orbits, generally a perihelion within the orbits of the inner planets and an aphelion far beyond Pluto. When a comet enters the inner Solar System, its proximity to the Sun causes its icy surface to sublimate and ionise, creating a coma: a long tail of gas and dust often visible to the naked eye.
