I had big plans for the Crash Course Astronomy episode about black holes, covering so many of the cool things about them.

In our final episode of Crash Course Astronomy, Phil gives the course a send off with a look at some of his favorite topics and the big questions that Astronomy allows us to ask.

It’s an example of an astronomical cycle visible to the naked eye, and the first of three subjects in Episode 3 of Crash Course Astronomy, a new series by Bad Astronomy’s Phil Plait.