Epicycle

every drawing is secretly spinning circles.

stacked rotating circles redraw any shape — even one you draw

Any closed curve, drawn by hand or otherwise, can be rebuilt exactly by stacking rotating circles at different speeds and radii — a Fourier series made visible. The same trick, adding up rotations, is what lets sound and images get represented and compressed as a short list of numbers instead of every point.

Concepts: geometry, motion.

An interactive you play with one thumb, on Wundr.