Man. Why didn’t they have stuff like this when I was a kid? Universe Sandbox is a space simulator that gives you the power to “control gravity, time and everything in it”…at least on your Windows-based computer. Although the developer says you can “smash planets together, introduce rogue stars, and build new worlds from spinning discs of debris”, some of the planetary impacts were a little disappointing. Moons might just sort of stick to the planet they hit. Hardly a significant drawback; the available simulations and the ways in which you can control them are amazing. One of my favorites right away was under “Fun Things To Do > Speed of Light”. Launch a light pulse from Earth and watch the circle slowly (on the grand scale) spread through the solar system. Knowing intellectually that light takes 8 minutes to reach us from the sun versus watching it happen was quite mind-expanding. This would be a great tool in the classroom and a blast for a science-minded kid. Take note though: strangely, the version you download is a 60 minute trial version. Kind of weird, but on the bright side, the purchase price is set by you if you decide to buy. Pretty cool.