At the centre of the Solar System is a star. The Sun is a huge ball of gas which provides light and heat to its planets. It contains 99% of all of the matter in the Solar System and, at 4.5 billion years old, is about half way through its life. Without the Sun, life on Earth simply wouldn't exist. The Sun is just one of millions of stars like it in the Milky Way galaxy but is the closest star to Earth. The next closest star is Proxima Centauri, nearly 268,000 times further away!