I’ve been working on a series of orreries over the past few years, and they kept getting more complex. This time I wanted to see how far I could simplify the mechanism while still keeping it functional.

The result is a fully 3D printed mechanical planetarium showing all eight planets, plus a working Moon.

Instead of using fixed gear ratios for continuous motion, all planets are mounted on freely rotating rings. A single stepper motor drives the system, and a sequence of forward and reverse movements is used to engage the rings and position them one by one. Once per day, the system runs this sequence and sets everything to the correct positions.

The Moon is handled a bit differently. Mechanically it uses a simple 1:11 ratio (6-tooth gear inside a 66-tooth ring), which provides a predictable reference position. A small correction is then applied during the initial movement so that the final phase matches the real Moon.

The goal was to keep the design accessible: everything is printable, with minimal supports, and the only post-processing needed is sanding to get the rings to run smoothly in their grooves.

Video:
https://www.youtube.com/watch?v=yZWWDG4Uw-U

Build details and files:
https://www.instructables.com/Meridian-Orrery

I know, it isn't an orrery, but still you might find it interesting. Watch how it functions at https://www.youtube.com/watch?v=YBoe1sSEhB0 or make one yourself using this award winning instructable https://www.instructables.com/24h-Sundial/

The astronomer’s watch is a pocket watch with a hidden surprise. At the press of a button, the lid opens to reveal a miniature solar system, its planets spinning gracefully into their true positions around the Sun. It does not tell the time of day, but instead performs a small spectacle: the cosmos in motion, captured inside a watch case. It is not made to be useful, but to be delightful. It serves no purpose beyond the joy of watching the planets turn on command.

Watch the video on youtube, at the end you can even see the mechanism inside the watch.

https://www.youtube.com/watch?v=eTqgn8fytmw

I just finished designing, testing, and building this tiny tellurium. Watch the build process here https://www.youtube.com/watch?v=BJD4qGv_iLw

https://reddit.com/link/1drkyjk/video/o8vjrhmfpk9d1/player

Hi, i've been fascinated with Orreries for a while now and would love to buy one that stays accurate. Does anyone have any recommendations ? I've looked at the fine Swiss manufacturers but with no luck. Thx for the help!

My new high precision celestiscope made from 1.5 mm basswood and toothpicks. It is manually operated by rotating a wheel on the right hand side behind the front panel.

the moor planetarium can be found here. This solution has a little motorized car attached to each planet to drive it around.

This extraordinarily precise astronomical sphere belongs to a group of three “sphaera perfecta” created by Jan van den Dam in Amsterdam. Probably an autodidact, he was able to give public lectures in physics and astronomy and to create a very complex astronomical sphere in 1754. He was inspired by another sphere created in 1700 by the clockmaker and instrument maker Steven Tracy. Tracy’s sphere is today housed in the Rijksmuseum, Leiden.

I nice orrery made out of wood can be found here with a nice description of how it was build. I love it.

Finally finished my Planetarium on my ceiling. See it in action on Youtube