Pixel Gravity is an N-body gravity simulator: a
computer program for creating imaginary astronomical universes--with
planets, solar systems,
or entire galaxies--and showing you what they would do in reality. It can make galaxies collide, build
a solar system with planets orbiting in any possible (or impossible) direction,
bombard Jupiter with Earths, or do anything else you want it to with various celestial objects.
Two merging galaxies. Click here if the video's broken. (Non-moving screenshots here).
It has lots of editing tools for
complex things in simple ways. Moving, editing, and orbiting
planets, as well as looking around your simulation, are all easily
doable with only your mouse. You can build
huge simulations or mess with a simulation while it's running without needing to type anything.
For more science-oriented users,
there are plenty of ways to view and edit the physical details of a
system directly, so you can do very exact and realistic simulations as
well as quick and simple ones. This program is precise enough to
correctly predict planetary transits, yet versatile enough
to make almost any kind of space-object simulation you can
All of this makes Pixel Gravity a useful tool for astronomy-related education
at any level, or just something fun to play with for anyone who likes astronomy.
There's a free demo version, which
does nearly everything the full version does, so go try
it out. If you like it or find it useful, you can buy the
full version (including future updates) from the download page.