This project is an N-body simulator, which means it calculates the effect of gravity between a number of different bodies (planets, stars, asteroids) to determine their orbits as time goes on.
It was written primarily as a toy for me to practice optimizing code that performs a lot of floating-point computation. As such, it is quite heavily optimized for the Sandy Bridge architecture (or later). I run it on an Intel(R) Core(TM) i5-2500K CPU @ 3.30GHz.
The universe.txt file included provides the starting point for the calculations. It was based on data from JPL's HORIZONS system, which can be found here.