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Earth, Sun & Moon (Motorized Gearbox Orrery)

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Build a motorized planetary orrery where a central gear turns the Earth around the illuminated Sun while the Moon orbits Earth. A micro:bit controls revolution speed and toggles Day/Night LED simulation.

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Props & Materials Required

  • •Laser-cut wooden planetary orrery gear set
  • •Styrofoam/plastic Sun (with internal LED), Earth, and Moon spheres
  • •TT DC gear motor or N20 motor
  • •L298N / DRV8833 motor driver board
  • •BBC micro:bit V2 controller
  • •Potentiometer speed dial

Step-by-Step Instructions

1

Assemble Planetary Gears

Mesh the central Sun gear with the Earth arm gear and Moon spur gear.

2

Turn Motor Speed Knob

Turn the potentiometer knob. The motor drives the main gear — Earth revolves around the Sun while spinning on its axis!

3

Observe Day and Night

Turn ON the Sun LED in a dark room. Watch how half of the spinning Earth is bright (Day) while the back half is in shadow (Night).

4

Moon Orbit & Phases

Observe how the Moon completes 12 small orbits around Earth for every 1 full revolution Earth makes around the Sun!

Why It Works & Notes

Earth's rotation (causes Day/Night) and revolution (causes Year/Seasons) are notoriously tricky to visualize. A 3D motorized gear mechanism makes relative speed and orbital paths crystal clear.