I seen this mentioned on the
Daily Galaxy website
for an interactive space simulator in which you can:
Smash planets together, introduce rogue stars, and build new worlds from spinning discs of debris. Fire a moon into a planet or destroy everything you've created with a super massive black hole.
You can simulate and interact with:
Our solar system: the 8 planets,160+ moons, and hundreds of asteroids
Nearest 1000 stars to our Sun
Our local group of galaxies
An unlimited number of fictional scenarios
I just spent the last hour playing with this I'd recommend you have a look at it if you can download the 17Mb installer
  