I have always been fascinated by astronomy and was excited when Crash Course announced their astronomy course. So far 15 episodes (each about 10 minutes long) have been released and I like them a lot.
Crash Course Astronomy is hosted by “Bad Astronomer” Phil Plait. He gives very understandable and comprehensive explanations of key concepts of astronomy, the solar system and planets.
You can find Crash Course Astronomy as a playlist on their YouTube Channel.
The whole Crash Course project (which includes many other excellent courses, such as World History, Chemistry, etc.) is supported by crowd funding via Patreon.