'This data visualization was created from real flight data. It shows the air traffic which flies on a typical summer day and highlights the intensity of the operation in Europe - an operation which runs 24x7x365.'
Discovering that the world was also round meant the people could use the system of celestial coordinates to describe points on Earth. The tricky thing was using astronomy to work out exactly where one must be. After all, the sky moved, and the Earth didn’t.
Mars in a Minute: How Do You Get to Mars?