The area where we live on the Flat Earth is encased within a Dome, or Firmament. In some texts its also referred to as The Vault of Heaven. Found in a very surprising amount of religions and societies, the idea can be traced to Babylonian, Sumerian, Egyptian, and Christian world-views, and likely a great many more. Even some Native American tribes were said to see the night sky like a tent. The stars? They were little holes poked in the hide of the tent.
As a scientific explanation it serves very well. It was after all only with Copernicus that we started to question the idea of the Firmament. By then we already knew quite a bit about calculating and predicting the movement of the heavens.