Our Solar System
Age: 4.6 billion years
The Solar System we live in contains the Sun, its eight orbiting planets and any other astronomical bodies that are under its gravitational pull such as comets and asteroids.
Comets originate from the Oort Cloud and Kuiper Belt, beyond Neptune, while most asteroids orbit in a region between Mars and Jupiter.
Mercury, Venus, Earth and Mars - the four planets closest to the Sun - are called terrestrial planets because they have solid rocky surfaces. Jupiter, Saturn, Uranus and Neptune are known as gas giants. Pluto, a dwarf planet, has a solid surface but is much icier than the terrestrial planets.
Our Solar System is just one star system among many within the Milky Way galaxy. There are 300 billion stars in the Milky Way and the nearest, Alpha Centauri, is 4.3 light years away. One light year is approximately 9,500 billion km, the distance travelled by light in one year.
There are around 100 billion galaxies in our Universe. So far, no one has detected life outside our home planet.
