S1, E1: Brian Cox seeks to understand the nature of time. From an extraordinary calendar built into the landscape of Peru to the the beaches of Costa Rica, Brian explores the cycles of time which define our experience of life on Earth. But even the most epic cycles of life can't begin to compare to the vast expanse of cosmic time. Just as the Earth orbits the Sun, the Solar system orbits the entire Milky Way Galaxy in a cycle that takes a staggering 250 million years to complete.