Put your science hats on, folks - it's another installment of MinutePhysics, although this week he goes for about three minutes to discuss why everything is dark at night.
The simple answer is "well, the sun's not shining", but after dismissing that, we get an exploration of the beginning of the universe, telescopes, infrared and the Doppler Effect. Feel free to quote the video at parties.
These videos are so awesome, I'm just going to give the URLs out to my son when he asks me these questions (they're coming any time soon now).
Keith Shaw rounds up the best in geek video in his ITworld.tv blog. Follow Keith on Twitter at @shawkeith. For the latest IT news, analysis and how-tos, follow ITworld on Twitter, Facebook, and Google+.