A1 dynamical astronomy orbit simulations
========================================
Here are the orbital simulations used in the lectures.  All use just Newton's 
laws to move frame-by-frame through the motion of the gravitating bodies.  In 
principle this is quite easy to program, but for added precision these routines 
use a "Runge Kutta" ordinary differential equation solving algorithm.  It won't 
be clear from the code how this works, so it's a bit of magic for now (see
http://en.wikipedia.org/wiki/Runge%E2%80%93Kutta_methods if you want the details).

The simulations are written in Python, using the Visual Python module for the 
animation.  Python is a Good Thing. You can install Python and Visual Python by 
following the instructions at http://www.vpython.org/. Once Visual Python is up 
and running you can run (and modify) the simulation file orbits.py . 

Alternatively, you can run the Windows executable held in orbits.zip without 
having to install Python.  Unzip these files and click on orbits.exe in the 
orbits folder.

Whichever you choose, you can select the simulation using 1--7 on your
keyboard.  The scene can be rotated using the RH mouse button and zoomed using 
both buttons.

Files in this folder
====================

orbits.zip -- the windows executable, if you don't want to install Python
orbits.py  -- the Python source file, for those who do
simple-3-body.py -- just the 3-body simulation, to show how short the basic code is!

Have fun!

Graham Woan