In 1950 Immanuel Velikovsky published his bestselling Worlds in Collision, where he proposed that Venus was once a satellite of Jupiter that went AWOL and caused catastrophes on Earth as it flew past. Nobody believes this now, and few believed it then either, but you can see how it would work using a solar system simulation designed by PheT.
It's a neat little program that simulates gravitational forces between bodies. You can change most of the parameters, such as the relative masses, starting positions and initial velocities. Put your ingredients together and let the universe spin! It's worth starting with some of their presets and then tweaking some parameters so as to get a feel for how your solar system will evolve.
This image shows the evolution of a three-body system which started out as the Sun, Earth and Moon but I increased the mass of the Moon and then slightly decreased its starting velocity. I didn't get a collision but eventually the Moon was hurled out into empty space!
Enjoy!
