Did you know that outer space exists outside of our atmosphere? The term outer space refers to the area outside of our planet's atmosphere, and is also the space between the celestial bodies. The vastness of space is fascinating and deserves more study. However, before you go on to learn about outer space and its many facts, you may want to consider some background information first. In this book, we will discuss some of the most interesting Outer Space Facts. The number of planets in our solar system is quite astounding. We have landed on every planet except for Neptune, which has no atmosphere and is so large that it would take over a century to travel there. We also know that the number of galaxies outside our solar system is staggering. Approximately 100 billion galaxies are known to exist. And the human race has only explored a small fraction of them. Despite its large size, the moon is not very big, measuring less than fifteen million square miles. That's less than one-fourth of the size of the pacific ocean. In fact, it's smaller than all of Asia! However, astronauts can see both objects in the sky at the same time, so this makes it easier to compare them. Despite these facts, it's still worth remembering that there are a number of other facts that we don't know about outer space.