Astronomy is full of astronomical numbers and if physics tells us anything it is that nothing is obvious. Astonishing facts about the universe are absolutely everywhere and you do not even have to go far from home to find some. There are 100 quadrillion cells that make up every human body. On Earth there are approximately 6.9 billion people, but if you gathered them all into one place, standing side by side they could occupy an island the size of the Isle Of Man all at once. Facts about time in the universe are pretty amazing, too, e.g. If the history of the Earth were compressed into 24 hours then the first humans would appear just 40 seconds before midnight. When you look at the sky you are seeing history, in fact when you look at anything you are looking at something that happened in the past. Some stars that we see today have already died in colossal supernovae, but things that happen to them we may not see for thousands of years to come on Earth. And there are more stars than there are grains of sand on the entire Earth... between 10 sextillion and 1 septillion. The mere notion of size and distance in the universe is itself difficult to grasp. For instance, the diameter (in metres) of the Virgo Supercluster, that's the cluster of galaxies including out own 'local group' of galaxies (about 200 million light years) is 2 1024 Try reducing that to regular integers on your calculator and taking it in! There are big meaningful numbers, but there are also big meaningless numbers. Some numbers, while full of meaning to physicists seem meaningless once we see them written down. One such example would be 'Planck density', or the density (in kg/metre3) of the universe at one unit of Planck time after the Big Bang, which is: 5,100,000,000,000,000,000,000,000,000,000,000,000,000, 000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000 (5.1 1096). But these are only the beginning of mind-blowing facts about the universe. Some of the best ones only concern the numbers in passing.