ELI5: Explain Like I'm 5

Fundamentum Astronomiae

Okay kiddo, so fundamentum astronomiae is a big phrase that means "the foundation of astronomy." Astronomy is the study of stars, planets, and other objects in space.

Now, imagine you're playing blocks. You have to put the big blocks at the bottom to make a stable tower, otherwise the smaller blocks on top might fall over. In astronomy, it's the same thing. There are a lot of small details to learn, but there are a few important big ideas that need to be understood first. These big ideas are known as the fundamentum astronomiae, or the foundation of astronomy.

One of these big ideas is that the Earth goes around the sun. You might think the sun goes around the Earth because it looks like that from where we stand, but scientists have measured and observed the movements of the planets for a long time and found out that the Earth actually goes around the sun.

Another big idea is that space is big. Really big. There are trillions and trillions of stars out there, each with their own planets, and they're all really far apart.

Understanding these big ideas is important because they help astronomers make sense of all the other details they study. So, just like with your blocks, having a good foundation is important for building up your knowledge of astronomy.