Skip to content The solar system is kind of hard to observe in motion all at once. Sometimes, it’s nice to have a little model to look at, so you can see the relative motions of celestial bodies play out in front of you. Such a device is called an orrery, and [illusionmanager] has built rather a nice example of their own. The build represents all the planets in the solar system, plus the sun and our very own Moon. An ESP32 lives at the heart of the build, running an astronomical simulation to calculate the proper positions of all the celestial objects. It then drives a small stepper motor via a TMC2209 driver, turning the mechanism back and forth until all the pieces are positioned correctly, using a reed switch and magnet to detect the initial zero position. The orrery is able to be driven by a single motor in this manner thanks to an ingenious mechanism, wherein the rings interlock with each other when turned in one direction, and not in the other.…