We found a simply beautiful Raspberry Pi project over at Instructables: this illuminated lunar phase clock.
Using John Conway’s lunar phase algorithm (that’s the same John Conway who invented the cellular automaton Game of Life in the 1970s), some simple circuitry (some soldering required, but this is an easy enough job), and a bit of elbow-grease for that handsome case, Aleator777 has produced an excellent tutorial that gives you all the steps you need to create your own lunar clock.
We love artistic, decorative projects like this one – and it’s a good way to teach your kids a little astronomy. Suggestions for improvements? (We note, for example, that Conway’s lunar phase algorithm only works for this century and last century.) Leave them in the comments!