At last week’s Crowdfunding SF Meetup, I was talking about Celestyme with a designer who suggested that a round display rather than dot-matrix with glyphs– to make it more like a digital orrery. This is more like my original design conception for the clock, which is why I reserved the domain digitalorrery.com a while ago, before I got celestyme.com. Hmm– which one? Both could presumably share a lot of the same back-end development, which is nice.
I think it would be totally lame to display the time in the middle with digits– you need hands. So I just searched around for optoelectronic components that might make good hands, but didn’t find anything good. No purpose-built analog clock-style displays. Some bar graph displays are curved such that you can make a circle with 12 of them, but the lines are so short. Others are long and thin, but you’d need a large and expensive number of them to make a clock face.
It seems easier, cheaper, and more elegant to go with a cheap electromechanical movement for the time in the middle, and then LEDs for the planetary positions. You can get clock movements for $3, and people have succeeded in controlling them from an Arduino.
Here’s a sketch of what this Digital Orrery version clock face might look like. The colored circles are LEDs (not exact colors) showing the same example time as the one used below, 12:30am GMT on January 25, 2014. They read outward starting from Mercury, just like the real solar system, and skipping Earth. Then an outer ring shows sun, moon, and rising/ascendant, without showing the phase of the moon like the dot-matrix version does.
Looking at the JPL DE421 ephemeris, and others from JPL, I’m intimidated at the prospect of figuring out how to calculate planetary positions from this data– it seems pretty complicated. Meanwhile, there’s a commercial software package called Swiss Ephemeris that’s based on the JPL DE406 ephemeris and purports to do exactly this. It seems to be written a couple of longtime dedicated astro geeks in Zurich, and informed by the Swiss national passion for accuracy and precision in timekeeping. It’s called the Swiss Ephemeris, and if you license it for your product, starting at around $680, you can also display their “Swiss Ephemeris Inside” logo.
If the planetary positions are indeed difficult to calculate, that suggests that my original idea of Arduino + SD card with JPL ephemeris might not have enough horsepower to do a good job. It might make more sense to go for a Raspberry Pi (or similar) running the Swiss Ephemeris. The whole software package fits on a CD-ROM (700MB), but I’m not sure how much of that is program code (which I think would need to fit into the Pi’s 512MB onboard) and how much is ephemeris tables that could easily on a 2GB SD card. Anyway, I’m gonna look into it. More expensive for sure, but it might be worth it to not re-invent the cosmic wheel and also have the #1 trusted name in planetary position calculation software.
Timepieces are fascinating, especially when they give you extra information, like the current phase of the moon or sunrise/sunset times. And whether you’re into astronomy, astrology, or both, it’s fun to know where the planets are currently in the sky.
Wouldn’t it be nice to have a clock that shows you not just the time, date, and moon phase, but also the zodiac locations of the sun, moon, and all planets, plus the rising sign and Mercury and Venus retrograde status?
And wouldn’t it be even more interesting and cool if the clock displayed this information digitally via a dot-matrix LED array, with all astrological symbols represented as 8×8 glyphs?