Sunday, July 29, 2007


According to Claudius Ptolemaeus, who proposed the Ptolemaic System, the Earth was the center of the universe, and each planet revolved around it. However some observations (such as retrograde motion, where a planet starts to go 'backwards' in the sky for a time) didn't match with a theory based on perfectly circular orbits. To account for this, Ptolemaic astronomers came up with the notion of an epicycle - each planet revolved about a point, which in turn revolved around the Earth. A bit like a spirograph, in fact.

Last night I started to wonder what it would look like if you had epicycles around epicycles around epicycles - fractal epicycles, if you like. Fifty lines of Python or so later, I had some crude pictures of the orbits planets might have in this strange alternate universe:

epicycle test 2

A few more examples here.


Blogger Tim said...

I like these, especially 115.

It's interesting what can be done with such a simple idea combined with randomness.

You made these with a script written in Python?

I remember studying the retrograde motion of Mars in a first year astronomy class. It completely confounded me until I saw it displayed visually at a planetarium.

7/29/2007 8:10 PM

Blogger Kerry Mitchell said...

Epicycles are cool. They are similar to the notion of Fourier clocks, wherein one hand rotates normally and another hand rotates from the tip of the first, half as long and twice as fast. This process continues indefinitely. It's the basis for my image Time.


7/30/2007 2:51 AM

Blogger Thomas said...

very interesting indeed :)

to what depth did you nest the cycles?

8/01/2007 3:51 AM

Blogger Kerry Mitchell said...

I believe that I went 6 deep.

8/01/2007 5:41 PM


Post a Comment

<< Home