Orrery

space · mechanical model · planets · astronomy

Planets in motion. An orrery is like a mechanical clock but for the Solar System, showing how Earth, Mars, Venus, and other planets orbit the Sun. As you turn it or wind it up, the model demonstrates the real paths and speeds of the planets.

Gears do the work. Inside an orrery are lots of gears and wheels that turn together at different speeds. Each planet's gear is sized so that the whole model accurately represents how long each planet takes to complete one orbit.

Size shortcuts needed. Orreries don't show planets at their true sizes because Jupiter would be enormous compared to Mercury. Instead, they use scaled-down versions so you can see all the planets and their orbits together.

Ancient Greek invention. People have been building mechanical models of the Solar System since the time of Ancient Greece, thousands of years ago. The name 'orrery' comes from a famous model made around 1712 by inventor John Rowley for a wealthy patron named Charles Boyle.

Based on the Sun. Orreries follow the heliocentric model, which shows the Sun at the center with planets orbiting around it. This is the accurate model of how our Solar System really works.