Simulation of retrograde moon orbit

Pre moon

It is assumed that our moon was not always in a stable orbit around earth. What is fascinating to me is the question how earth did capture the moon, in a stable orbit, with or without a collision.

Nowadays we have computers and can run simulations to answer a question, what would happen if ....?

So i did setup a simulation with Universe sandbox with lots of assumptions about how the planetary system would look like back then. I know, this is not very scientific, nevertheless there are intresting observations to be made, which i didnt anticipate.

How i started is roughly to see in this picture.


I let the simulation run for eons (you need a beefy setup for this) and quickly discovered some things i didnt expect:

  • The Orbits of the planets slowly got on a flat disk-line, like if there was a disk attracting them. This is due to the larger planets which pulls earth and moon towards them, making the orbits disk like.
  • The change of a collision seams to increase, if the orbits are not spherical. However i could not find a simulation starting point where collision earth moon would occure, it missed each time by a hair, giving earth a small nod to its orbit. This is really nice to observe. I didnt expect that to happen.
  • In the end the simulation reaches a point where there are only stable orbits. Nothing intresting would happen from that point.

All in all i learned something.

If you also own Universel sandbox, you can download this setup and repeat this simulation. Be patient this can take a while.