Youtube keep taking this down but it keeps coming back. Also this is an opportunity to remind you that as we go through the course you can click on the labels at the bottom of the posts to review past postings. For example as well as my yearly version of this post the Abiogenesis label has a small, but interesting, collection of posts
For everyone who has ever wondered what it would be like when a 500km diameter asteroid crashes into the earth here's a simulation. Asteroids of this size would have impacted the earth during the late heavy bombardment I mentioned. 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.