The Big Bang, Cosmology part 1: Crash Course Astronomy #42

Thanks to observations of galaxy redshifts, we can tell that the universe is EXPANDING! Knowing that the universe is expanding and how quickly its expanding also allows us to run the clock backwards 14 billion years to the way the universe began - with a bang. Crash Course Astronomy Poster: -- Table of Contents Distant Galaxies Show a Red Shift in Their Spectra 2:07 The Universe is Expanding 2:51 This Model is Called “The Big Bang” 5:12 The Universe is Almost 14 Billion Years Old 11:43 -- PBS Digital Studios: Follow Phil on Twitter: Want to find Crash Course elsewhere on the internet? Facebook - Twitter - Tumblr - Support CrashCourse on Patreon: -- PHOTOS/VIDEOS Hubble Goes to the eXtreme to Assemble Farthest-Ever View of