The Sun is an imposing presence in our Solar System, providing the heat and light that sustains life on Earth. The Sun was created in a cloud of gas and dust 4.6 billion years ago. Gravity brought clumps of the cloud together, while the temperature and pressure at the centre rose until it became hot enough for nuclear fusion to take place.
With a radius of around 700 000 kilometres (more than a hundred times larger than the Earth's) the Sun dwarfs all the planets in the Solar System and contains 99.8% of its mass. The Sun has a north and south pole, just like the Earth, and rotates on its axis. A planet's distance from the Sun can determine whether it's able to sustain life. Those too close experience extreme temperatures, while those too distant are so dark and cold that life cannot survive. The light from the Sun is so intense that even here on Earth, some 93 million miles away, it is dangerous to look at the Sun with the naked eye.
