The sky may not look very different each night, but the stars that light it up are moving away from each other at a speed of hundreds of thousands of kilometres a second. Even more amazingly they have been doing this for between 10,000 million and 20,000 million years! That is the period when scientists calculate that the universe began with a huge explosion. They call this the Big Bang. When the Big Bang happened, all the matter in the universe exploded from a tiny point of fantastic energy shooting off in every direction. The galaxies, stars and planets in the universe were formed from this matter. And the Big Bang was packed with such force that they are still hurtling away from each other at incredible speeds thousands of millions of years later.
Picture Credit : Google
