Having just gone through the daylight savings change here in Europe, I found this really fascinating: how __do__ you set up time for the moon where time, at least as we understand it, doesn't really exist?

I'm sure that, starting from scratch on Earth, we'd probably come up with a system of time zones that is broadly similar to what we have today but with some new zones and some adapted zones. Then again, maybe we'd find a way to change things up altogether - is there any value to GMT being based on Greenwich if the UK is not the global power it once was?

Would time zones even be necessary on the Moon ? Sunrise and sunset occur on a scale of Earth days, not Earth hours.

Nope, no time zones. Just one time zone that is "the moon". But somebody somewhere needs to make a standard for that, and this is it.

Still tho, how about a prime meridian centered on where Neil Armstrong first set foot ?

They don't need any meridians. The entire place will be one zone. The time will be the same everywhere.

The problem is that the time there will move very slightly differently than here on earth, because of the lower gravity, to the tune of 60 ms per day. That's almost a second every two weeks.

So the question isn't "what time do we set the clocks to?" but "what time will it be an hour from now?" Have a leap-second every few weeks?

> Have a leap-second every few weeks?

Well, we have the software ready for it.

And yes, a prime meridian is not necessary, but NASA loves to name things. How about the Wright-Gagarin-Armstrong Meridian ?

60 µs per day, not ms.

GMT is a time zone used in Britain. It is no more special than any other. The standard is UTC.

If engineers were in charge, there would be no time zones. Brits would get up at 08:00, Indians at 04:00, and Americans at 12:00/13:00/14:00 depending on location. Shops would set their opening hours relative to local sunrise. It's already the case that work-shifts span calendar days for many people, and that franchise locations have differing hours of business, and that fuckwits telephone you when you're trying to sleep.

People's eyes glaze over when I rant about this. But yes, I fantasize about a world where you could say "let's set up a video call at 6" and there's no mental math when there's geographic distance involved.

Biggest downside I can think of, apart from the entire population groaning about making the switch, would be the confusion from reading literature from the before times. Oh, and all blood, sweat, and tears of all the devs who created timezone code going down the drain.

Some industries do this using UTC. For example flight departure and arrival times are in UTC on all paperwork. And also the meteo reports and forecasts, and airspace restrictions, and airport opening times etc.

Mostly out of a necessity that fights tend to cross timezones and planes come and go from all over the world and they don't want to have to figure out everywhere what the local time is.

Really only passenger info screens convert to local time.

The biggest downside would be the date rolling over during a record-keeping period. But this is already a problem and people handle it just fine. I mean, we say "tonight" for 02:30 on the following day, so meh.

No no no. We can't make the world adjust to our crappy code.

24:00 is "mid night". 02:30 is not less 'tonight' than 21:30, assuming no DST.

> But this is already a problem and people handle it just fine. I mean, we say "tonight" for 02:30 on the following day, so meh.

Because that only affects the comparatively small number of people awake respectively events happening at that time of day. If you move the calendar date change right into the middle of the waking hours of almost everybody else, things get quite a bit more annoying.

I'm willing to make that sacrifice if we can delete python's time zone library.

Swatch tried unsuccessfully to sell people on this idea back in the late 90s:

https://en.wikipedia.org/wiki/Swatch_Internet_Time

> If engineers were in charge, there would be no time zones

We might not specifically have time zones, but we'd have something that is equivalent.

We live on an approximately spherical world, its rotation is not tidal locked to its star, its rotational axis is not perpendicular to its orbital plane, we evolved to synchronize our biological rhythms including our sleep/wake cycle to local sunrise and sunset, we occupy a wide range of latitudes and longitudes, and we need to coordinate activities with people who are far away from us.

That puts a lower limit on the complexity of our time keeping system.

Instead of time zones, we'd have variable customary times for meals. I call that a reduction in complexity.

You are just moving the complexity from your date widget to the user, who in the end probably is better of using a sun dial.

This is how it works in China. China has one time zone, so if you are in Xinjiang, you just go to work/school a bit later than if you are in Shanghai.

Only engineers that haven't thought this idea through: https://qntm.org/abolish

Fortunately they're not in charge.

> It's already the case that work-shifts span calendar days for many people

They're still only a small minority a people, though. (In Germany for example ~5 % of people regularly work night shifts.)

Without timezones, in locations further away from the meridian a far larger number of people will suddenly be impacted. Having the calendar day change smack in the middle of waking hours of most people is rather annoying.

I am extremely glad engineers are not in charge. Only an engineer (with a teeny-tiny dash of mid to high levels of egoism because of presumably how smart he thinks he is; the keyword being "thinks") thinks of humans as nothing else except extremely mechanical machines

If they're going to bother creating a time measurement system for the moon they might as well just invent the Stardate already and use that for everything we do in space from now on regardless of where we are.

Time to add a `--stardate` flag to the `date` command then?

Maybe just --star

> might as well just invent the Stardate already and use that for everything we do in space from now on regardless of where we are

Until we have FTL, that isn't physically possible. If we do, GMT comes with backwards compatibility.

Tcl is once again ahead of the curve with a stardate format option (%Q)

> Coordinated Lunar Time (LTC)

Ah yes. It appears that the French have already seized control of the appellation process. Except that French media are reporting it as "le temps lunaire coordonné" (TLC?). So the White House seems to be (somewhat blindly?) reproducing the oddity of how "UTC" (with the letters in that order) isn't quite "Universal Coordinated Time".

Inventing metric gives them a gravitas in the field of metrology that America lacks.

Ain't it the truth

Accuracy counts. "... a moon-centric time reference system that accounts for its differing gravitational forces. In a memo on Tuesday, OSTP chief Arati Prabhakar noted that Earth-based clocks would appear to lose 58.7 microseconds per Earth-day as a result of these factors."

Simple fix. Make the whole moon GMT. Reset the clock every day at 00:00 to account for slippage. For time keeping on the moon just have a moon time off some atomic clock.

"Works for me!"

It's probably time to start the Falsehoods Programmers Believe About Lunar Time article.

Falsehoods Programmers Believe About Spacetime

You can only travel forwards at 1 second per second.

> ... that accounts for its differing gravitational forces ...

I salute maintainers of timezone libraries. This is going to be a fun one. You are now responsible for space and time.

This comment made me curious.

Apparently, TAI specifically defines the second (in terms of cesium transitions) at sea level (where gravitational potential is equal). I never knew that second part.

...and one level of language-precision further, these articles get into how "sea level" differs from "where gravitational potential is equal":

https://en.wikipedia.org/wiki/Ocean_surface_topography

https://en.wikipedia.org/wiki/Geoid

I just know this is going to take weeks or months of planning meetings, stakeholder sensing sessions, and arguments over minutiae. Not a good use of official time and taxpayer resources.

It's all arbitrary anyway. Just pick something that makes sense. UTC, UTC+1 (ESA), UTC-6 (Houston), whatever.

It's not about a "timezone", the article is about high precision time keeping and how to set a standard for it on the moon.

Because (according to the article) an earth clock when moved to the moon wold be a few micro seconds per day slower then it was on earth, causing drift.

So just setting UTC or UTC+1 isn't the ting they're trying to decide. It's more about a scientific method to derive highly accurate time on the moon, which can't just be earth type atomic clocks because they would drift.

Wouldn't the solution be to use microseconds? Maybe I'm just being naive, I love science, but as I get older it gets hard to keep all the whims of tech in my head.

tech/science*

Yes, that would be the solution.

Do you know how to make a microsecond on the moon? No, you do not. No one does. NASA has been assigned to figure it out.

A clock that ticks in microseconds on Earth will tick in (local) microseconds on the Moon.

No, no. Time is a function of the gravitational field. Two different masses, two different ticking and tacking.

The consensus is that gravitational time dilation occurs has a constant effect, not that it's qualitatively different in some complicated way that requires a Presidential directive to figure out.

Do you have any evidence that they're more "different" than Earth "local microseconds" versus moon "local microseconds"?

A microsecond up there is different from a microsecond down here, because of gravity difference, kinda like interstellar but much much more subtle.

See discussion on BBC version of this story here:

https://news.ycombinator.com/item?id=39916102

Watch them try to integrate it into earths time and calendar system somehow

"U.S. leadership in defining a suitable standard - one that achieves the accuracy and resilience required for operating in the challenging lunar environment - will benefit all spacefaring nations," - some American who believes the US should be the authority for this, shockingly.

Why would anyone bother following the US standard for lunar time? They can't even work out the metric system.