Okay, I'm allowed to have the odd repeat. I think I shall make it a tradition to start this course with a bang.
We didn't actually get onto abiogenesis and the very early history of the earth today (don't worry we'll get to it later). However I don't think I'll let that stop me posting this clip from the Discovery Channel. For everyone who has ever wondered what it would be like when a 500km diameter asteroid crashes into the earth. If you go to YouTube to watch it you can click a little link to watch it in high def. (highly recommended). You might also want to wait until you can crank up the speakers. The perfect soundtrack to the end of the world.