Monty Python's "Galaxy Song"!
The Denver based Smash Syndicate's cover of Sun Ra's 'Space is the Place' song redone to say 'Space in your Face!' http://www.youtube.com/watch?v=wVZ1NDC6pl4&feature=youtu.be
"Supermassive Black Hole" as well as "Neutron Star Collision" - both are by Muse! They have many science, sustainability, and spacey songs so you nerds who aren't familiar with them should listen to their music!
Also, I must say the Big Bang theory intro is quite good.