Not sure if you guys have heard of this game yet. It is a fun physics game that lets you make rockets and fly them into space. Right now there is only the planet and the sun, but next update should include a moon!
It's free for now, but if you do the donate/pre-order you will get all updates and the full game for a lot less than what the game will cost when it's complete.
http://kerbalspaceprogram.com/index.php
KSP
Moderators: MorGrendel, hypo