I'd recommend a couple of songs by Christine Lavin--"Planet X" and "If We Had No Moon." You can find them on YouTube or buy them on iTunes. There's a neat video on YouTube set to the music for "If We Had No Moon".

"Planet X" is about Pluto--it's a little outdated, but full of great info regardless. Plus, I have to say that the fact that she can set the phrase "International Astronomical Union Working Group for Planetary System Nomenclature" to a catchy tune makes her one of my personal heroes.

"Planet X" lyrics: http://www.christinelavin.com/index...her_Really_Does_Know_Best&display=35

"If We Had No Moon" video: