Orrery (Orrery Gravitational Systems) was conceived as a desk-top laboratory in which I and my students could explore the complex behaviour of gravitational systems.  All activity is 2-dimensional, making the interactions of celestial bodies uniquely visible.  Students can construct their own solar systems and watch them evolve.


OrreryGS (Orrery Gravitational Systems)

An orrery is a model of the solar system, named after the 4th Earl of Orrery (of Ireland) who had an interest in science and was a patron to the designer of the first mechanical model of the solar system. I have always been fascinated by such models since I first saw one as a child, and built my own in software when I first got a PC in 1984.  It was with the first distribution (to friends) of the software "Orrery" that I decided to brand my hobby products by the name "Orrery Software". 

A solar system is a complex adaptive system in which the size and placement of the planets is continuously adjusting to chaotic variations in orbits through negative feedback mechanisms. This software does not emulate or attempt to reproduce physical reality. Rather, starting from initial conditions, and driven by iterated applications of the laws of gravity, all of these orreries develop according their own internal changes. With this software you can examine working versions of the early Greek models of the universe, and working versions of each of the known planets with their assemblage of rings and moons. It includes the only working Ptolemaic model of the solar system that I am aware of.  

You can also create your own gravitational systems using the "tinker" wizards. This is where you can gain real insights into how gravity works. All gravitational interactions have been collapsed to two dimensions to improve understanding through visualization. The tinker wizards take a little effort to learn to use. If you want to know where the moon will be at 10:30 this evening, this is not the software for you. However, if you want to see a simple solar system form in a few minutes in front of your eyes, and you want to understand how this could happen, this software is for you. To download it, click here OrreryGS.zip (1.1 Mb). The help files associated with OrreryGS are extensive but are designed to function in Windows XP or earlier.  If you wish to make the help files operable in Windows Vista, Windows 7, or Windows 8 environments, visit this site and install WinHlp32.exe on your system.  To go to the download site, click here (http://support.microsoft.com/kb/917607).


Starting with a star and a swirling cloud of particles. (above)

Planets form in minutes as ejecta is tossed spacewards. (below)

Last updated: September 2014.