The theories explaining many astronomical observations come from an iterative process of forming a general theory, designing a model, testing and refining. This project aims to retrace the steps leading to some of the astronomical theories which are now considered fact.
The focus will not be on state of the art and very complex astronomical models and the maximal degree of realism. Instead it will be on creating the simplest possible models which still realistically demonstrate the mechanisms at work at a level of accuracy that would make them relevant for introductionary astronomy courses.
A couple of videos can be found on youtube. Unfortunately they turned out a little dark during compression so they should probably be viewed in full screen to be interesting.
A protoplanet is impacted by a slightly smaller protoplanet. The collision blasts material outwards, but not far enough to form as moon. This is a "failed" experiment trying to form an orbiting moon. This problem, along with a successfull experiement is described in the paper.
A fluid planet with zero initial momentum is accelerated towards a gravity source. As the fluid planet gets closer to the gravity source, it is deformed by the difference in gravitational pull on the near side and the far side.
A fluid moon is given an initial motion vector which puts it in orbit arround a gravity source. The orbit is however within the Roche radius and the difference in gravitational pull (the tidal forces) breaks the moon into smaller pieces which eventually form an orbiting disk around the gravity source. Transferance of momentum due to viscosity in the orbiting material makes some material fall into the gravity source while other material is thrown out in a higher orbit.
A cloud of particles with small random motion callapses under its own gravity. As the cloud shrinks in size, it begins to spin faster in order to conserve angular momentum.
This video shows the dynamic spetial subdivision tree used for the Barnes Hutt N-body approximation of gravity. This is explained in detail in the paper
The videos below are of an earlier 2D version of the simulator which actually had walls surrounding the scene. This causes the particles to sometime bounce off the walls. The simulations are otherwise interesting enough to watch.
A rotating disk of particles clump together and form many orbiting "planets". These planets collide and combine into a few larger planets.
Another rotating disk forms objects and during this we see a matter bridge connecting the central body with the orbiting ones. Eventually the tidal forces "breaks" the moon and the low orbiting parts are caught by the planet and this speeds up all the moon material. This is both due to the tidal bulge on the planet accelerating the moon which is in a prograde orbit and the transferance of momentum from the low part of the "broken" moon to the higher orbiting parts. This throws the last of the moon out into a higher safe orbit outside the Roche radius. Here it stays.
Yet another "solar system creation" with the old version of the code. Here the "planets" are held together both by gravity and by surface tension. Obviously, on an astronomical scale, surface tension has no relevant effect, but still this shows some interesting things such as sling shots, planets breaking up when close to a gravity well and so on.