Ancient Skies

NARRATOR

But mapping the Earth was dwarfed by Ptolemy's crowning achievement. An epic project, using math and geometry to chart our vast and constantly moving heavens. And the starting point of this new map was one of the most fundamental ideas in ancient astronomy. Every year, we send hundreds of satellites into space. They orbit our Earth at up to 17,500 miles per hour. Without them, modern life would grind to a halt. But this space-age technology effectively operates on an ancient idea. Satellites behave as if the planet they orbit is the center of the universe. It's a concept that's not quite as crazy as it sounds. We do not experience the Earth as moving. We experience the Sun as moving around us. It's experientially true, it's the world we live in.

NARRATOR

Wherever you stand on Earth, the skies and everything in them appear to move around us. For Ptolemy, this wasn't just a matter of perspective. It was a matter of fact. An Earth-centered universe. The first building block in a model that would shape our understanding of the skies for the next 1,500 years.