Epicycle

every drawing is secretly spinning circles.

a ball carves a shape into sand, pulled by circles turning on circles; draw your own

Any closed curve can be rebuilt by stacking rotating circles at different whole-number speeds and sizes: a Fourier series made visible. Few circles give a rough outline; more circles sharpen it. The same idea, adding up rotations, is how JPEGs, MP3s and MRI scans are built and compressed.

the same trick, circles added up, builds every JPEG, MP3 and MRI scan.

Concepts: geometry, motion.

An interactive you play with one thumb, on Wundr.