For hundreds of years, the clockwork orrery has been a way to demonstrate the movement of planets around the sun - as Wikipedia describes them: "An orrery is a mechanical model of the Solar System that illustrates or predicts the relative positions and motions of the planets and moons, usually according to the heliocentric model. "

It occurred to me that, the circular display of ten neopixels on the Circuit Playground might be a way to make a different kind of orrery... so I did. My programs are in this repository and consist of three programs:

• orrery.js - Javascript/Makecode version for the Circuit Playground (https://makecode.com/_EHeh61h4Dcvo for the Makecode IDE version)

• orrery.py - Circuit Python version for the Circuit Playground (copy to code.py on the device)

• neo-orrery.py - Circuit Python version for the NeoTrinkey  - again, copy to code.py on the device (you didn't think I'd leave the NeoTrinkey out did you?)

I opted to just do Mercury, Venus, Earth and Mars - adding more planets was too cluttered, plus the relative speeds of the inner planets are easier to see.

All versions start by showing Mercury (pale white), Venus (yellow), Earth (green) and Mars (red) as neo pixels moving at their relative speeds around the sun - from Mercury the fastest to Mars the slowest.

Each can switch to a random setting, changing the color and speeds of the four planets.

Makecode version: "A" stops/starts motion, "B" sets up a random solar system, and "Shake" resets to defaults.

Circuit Python Playground version: "B" sets up a random solar system and "A" resets to defaults

Circuit Python NeoTrinkey version: Touch pad #2 to get a random solar system and pad #1 to reset to defaults

NOTE:

The mechanics of the simulation are simple. Each program has a loop that increments a counter for each "planet."  There is a table of periods for each planet, an integer that is 100 times the length of the planet year, so, for example, Mercury's period is 22 and Earth's is 100. When a planet's counter reaches the value of its period, the counter is cleared and the planet's position is advanced one position.