The solar eclipse puts the race to unify Moon time in the spotlight

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Not only does it illuminate a new Space Race for precision-timekeeping on the Moon, it shows just how strange time is at every level.
Cut to 2024 and NASA has been tasked to work with international agencies to create a lunar standard time, known as Coordinated Lunar Time (abbreviated to ‘LTC’).
Even more intriguing, neo-futurist watchmakers SpaceOne have been working on a solution with the car designer Olivier Gamiette, and their Tellurium watch will launch at Watches and Wonders 2024 in Geneva this week.
The moon is tidally locked so that the earth is no use as a time reference, leaving the sun as the only answer.
This is fine, save that the ‘synodic’ lunar day is 29 days, 12 hours, 44 minutes and 3 seconds (on average – terms and conditions do apply) giving mañana a whole new meaning.
You can cheat by using an earth longitude meridian which will be in line every 24 hours (plus 50 minutes because this is the moon).
The other approach is to physically model the earth and moon within the wristwatch as in Ulysse Nardin’s fabulous Tellurium watch.
One of a trio of astronomical watches designed by watchmaker-inventor Ludwig Oeschlin in the late 80s, the Tellurium shows the relative positions of the Sun, Moon, and Earth with respect to each other.


Only one week after the US Office of Science and Technology Policy ordered NASA to create a lunar standard time by 2026, tonight’s solar eclipse sheds light on our current fascination with the Moon. It reveals a new Space Race for accurate timekeeping on the Moon and highlights how peculiar time is in general.

The peculiarities of space time were beyond even Stanley Kubrick’s imagination.

When American watchmaker Hamilton was given the assignment in 1967 to design Heywood’s watch to wear on his Pan-Am shuttle to the Moon station in 2001: A Space Odyssey, even the notoriously meticulous Stanley Kubrick was unable to explain just how strange time is in space. The general cosmic thinking stopped short of asking whether anyone in orbit around the Moon could benefit from a standard dial and GMT hour window.

In 2024, NASA is expected to collaborate with global organizations to establish Coordinated Lunar Time (abbreviated as “LTC”), which will serve as a lunar standard time. Even more intriguingly, neo-futurist watchmakers SpaceOne and car designer Olivier Gamiette have been developing a solution, and this week’s Watches and Wonders 2024 in Geneva will see the introduction of their Tellurium watch. I’ll talk more about that later because understanding the science underlying this very contemporary Space Race is helpful.

Unified lunar time creation involves complex and unusual physics.

There are a lot of variables to consider in the complex and strange physics of creating LTC. For example, at the current precision level of atomic clocks, it is claimed that you can only determine the time of an event that has already happened, with the current time being an estimate that is subject to change. The peculiarity that time moves more quickly on the moon (averaging 58.7 microseconds per day) due to gravity differences adds yet another level of complexity to timing on the moon. It makes sense that when you travel to another body, like the Moon or Mars, that each one gets its own heartbeat, NASA’s Kevin Coggins told the New York Post last week, albeit not in a very helpful way. A computational nightmare, for sure, but not particularly relevant to the wrist gear you’ve decided to pack for your moon trip (have you booked yet?).

The sun is the only solution because the earth is useless as a time reference.

When you go all the way to the macro level, lunar time becomes almost as bizarre. The sun is the only source of information because the moon is tidally locked, rendering the earth useless as a time reference. This is all well and good, but the “synodic” lunar day, which has an average length of 29 days, 12 hours, 44 minutes, and 3 seconds (subject to terms and conditions), gives a whole new meaning to the word “mañana.”. What therefore is the remedy?

An earth longitude meridian, which will line up every 24 hours (plus or minus 50 minutes due to the moon), can be used as a workaround. This kind of variation is something that a wristwatch movement could easily accommodate. I called around to several watchmakers in the business, and two of them said it was “a very interesting question” (which is Swiss for “I’ll call you”). A separate hours and minute train operating off the main movement would appear to be the easy way forward (the difference in time speeds being too small to worry about), according to a watch-movement designer with deep connections in the industry who spoke to me under condition of anonymity.

Jean-Marc Wiederecht, the creator of the Swiss movement design experts Agenhor, who has completed intricate technical briefs for Hermès, Fabergé, and H, supported this. leading watch brands, including Moser. Wiederecht says, “In such a case, an interesting function could be to display two different times, LTC and GMT on Earth, but I don’t think you would find the clients for this.”.

After some time, my anonymous source suggested that “you’d need something similar to the ‘Equation of Time’ complication that tracks sunset and sunrise times through the year if you wanted to track the true lunar day on a wristwatch.”. He declined to say if anyone was actually working on the watch.

As in the case of Ulysse Nardin’s amazing Tellurium watch, an alternative method involves physically simulating the earth and moon within the wristwatch. The Tellurium, created by watchmaker-inventor Ludwig Oeschlin in the late 1980s, is one of three astronomical timepieces that displays the relative positions of the Earth, Moon, and Sun. Although the Tellurium already indicates how much of the true moon day has passed on the outer ring of the dial, I’m sure Ulysse Nardin could be convinced to change the display from being earth-centric. After all, they’re made to order.

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