♥ A graphic showing all 8 planets in our solar system, Mercury through to Neptune, to scale where one pixel = km. Scales were worked out with this very useful solar system scale calculator. Find out more about the planets on the Planet Facts page.
When Galaxies Collide: How The First Super-Massive Black Holes Were Born - Two black holes merge to become a supermassive black hole. It is thought that the first supermassive black hole was created 13 billion years ago.