December 3rd, 2012
Episode 317 of 474 episodes
Our Universe appears timeless and unchanging, the stars taking their nightly flight across the sky. But over long periods of time, you realize that our local region, and even the entire Milky Way is in constant motion. The constellations we see today would be very different millions or even thousands of years ago. Today we'll discuss stellar motion, how astronomers detect it and how it's useful.