analemma

3 Articles

Geochron world time clock

Geochron: Another Time, Another Timeless Tale

October 26, 2024 by 10 Comments

The Geochron World Time Indicator is a clock that doubles as a live map of where the sun is shining on the Earth. Back in its day, it was a cult piece that some have dubbed the “Rolex on the wall.” Wired’s recent coverage of the clock reminded us of just how cool it is on the inside. And to dig in, we like [Attoparsec]’s restoration project on his own mid-1980s Geochron, lovingly fixing up a clock he picked up online.

[Attoparsec]’s recent restoration shares insights into the clock’s fascinating mechanics. Using a synchronous motor, transparent slides, and a lighted platen, the Geochron works like a glorified slide projector, displaying the analemma—a figure-eight pattern that tracks the sun’s position over the year.

But if you’re looking for a digital version, way back in 2011 we showcased [Justin]’s LED hack of FlorinC’s “Wise Clock”, which ingeniously emulated the Geochron’s day-night pattern using RGB LEDs, swapping out the faceplate for a world map printed on vellum. That’s probably a much more reasonable way to go these days. Why haven’t we seen more remakes of these?

A Look Inside The Geochron Clock

May 31, 2024 by 6 Comments

There are plenty of cool clocks out there, and maps by their very essence are cool, too. But a map that’s also a clock — or is it a clock that’s also a map? — has to be the coolest thing ever.

Of course we’re talking about the Geochron, a world clock that makes the relationship between the Earth and the Sun clear and has graced the offices of executives who want to impress visitors with the global nature of their importance for decades. [Attoparsec] has long coveted one of these electromechanical beauties, and when a used one popped up online for a pittance, at least compared to what they cost new, he jumped at the chance.

The Geochron he ended up with was in need of some TLC, but surprisingly little considering its mid-1980s vintage. The real treat in the video below is getting to see how these wonderful devices work. They’re basically simple slide projectors. While we here in the future would simply do everything in software on a nice flat-screen display, the base map, night-day terminators, and calendar are all contained on transparent elements that move under the power of a synchronous motor across a lighted platen. The analemma display is particularly cool; an indicator tracks the Sun’s position over the Earth with a cam that encodes the equation of time in its shape, moving through its familiar bi-lobed loop as the seasons progress.

Any clock that comes with a set of blueprints for installation purposes is alright in our book, and kudos to [Attoparsec] for landing this prize and getting it back in shape. His description of it as “the greatest clock of all time” is apt, but perhaps with a little competition. Or maybe a lot.

Continue reading “A Look Inside The Geochron Clock” →

Chandelier Mimics The Solar Analemma

September 24, 2022 by 14 Comments

The solar analemma is the shape the sun traces out when photographed each day at the same time and same location for a whole year – but you probably knew that already. [makendo] decided to use this skewed figure-eight shape as the inspiration for a chandelier, and the results are stunning.

A laser cutter was used to cut out segments of the analemma shape in plywood, such that they could slot together into the full form. These were then glued together on to a plywood sheet as a template to cut out the full-size form in a single piece. Some laminate edging was then added and the entire thing was given a coat of black gloss paint. String lights were cut up to provide the many globe fittings required, and installed on the back of the chandelier.

[makendo] notes that with a full 51 bulbs in the chandelier, it’s way too bright for most dining room settings. A dimmer is thus used to tone down the output to reduce eyestrain at mealtimes. It’s a fun build, and we’ve always loved light fixtures that are inspired by astronomy. If you like the moon more than the sun, though, there’s a build for you too!