4THE COPERNICAN SYSTEM. The orbits are not to scale, of course, but the rotational periods are proportionally accurate. The Earth completes one “year” in 20 seconds, while Mercury revolves in 4.8 seconds and Saturn in 590 seconds.

This demo uses the rotation.css stylesheet to position the “fixed stars” around the solar system; no other elements require it.

1. Ptolemaic System • 2. “Egyptian” System • 3. Tychonic System • 4. Copernican System