back to article If we plan to live on the Moon, it's going to need a time zone

There are a lot of technical challenges humanity will have to tackle as we prepare a long-term presence on and around the Moon, and the European Space Agency just reminded us of one more: we don't have an agreed, coordinated method of telling time on our natural satellite.  That hasn't been a problem up until now, the ESA …

  1. Lil Endian Silver badge
    Coat

    Just ensure that every visitor to the Moon has bad teeth. That way it'll always be tooth hur.... No! Nope, I can't say it!

    1. MyffyW Silver badge

      I wasn't sure where you were going with that - bad teeth often being a synonym for us inhabitants of this sceptered isle, I thought you might be making a vote for Greenwich Mean Time. But have an upvote anyway.

      1. Anonymous Coward
        Anonymous Coward

        British oral health is actually better then in the US:

        https://dentistry.co.uk/2016/01/06/english-have-better-teeth-than-americans/

        1. jake Silver badge

          Consider the source ... They WOULD say that, now wouldn't they?

          1. Anonymous Coward
            Anonymous Coward

            The original source was UK & US researchers looking into English and American dental surveys. As noted in the article if you had read it.

  2. jake Silver badge

    Just set the entire moon to Coordinated Universal Time (UTC +0) ...

    ... and be done with it. No need for that fscking useless so-called "daylight savings time", either.

    Works for the ISS, and various other bits of space debris junk kit.

    1. elsergiovolador Silver badge

      Re: Just set the entire moon to Coordinated Universal Time (UTC +0) ...

      Create a special tax zone, setup a bank and call its offer the "moonlight savings time", for all the people doing a little bit of moonlighting to afford their Avocados.

      1. Anonymous Coward
        Anonymous Coward

        Re: Just set the entire moon to Coordinated Universal Time (UTC +0) ...

        You're trying to get all of them in the B Ark, aren't you?

        Nice try :).

        1. Snowy Silver badge
          Coat

          Re: Just set the entire moon to Coordinated Universal Time (UTC +0) ...

          Given what happened to those that stayed behind, I think the B ark is the best choice :)

      2. Tubz Bronze badge

        Re: Just set the entire moon to Coordinated Universal Time (UTC +0) ...

        Speaking of taxes, as no one nation owns the moon, how do you tax people, as technically working abroad in international free space?

        1. Anonymous Coward
          Anonymous Coward

          Re: Just set the entire moon to Coordinated Universal Time (UTC +0) ...

          Presumably they are still being paid at home?

        2. ThatOne Silver badge
          Devil

          Re: Just set the entire moon to Coordinated Universal Time (UTC +0) ...

          It will certainly be owned by corporations, and they know how to get their money back: Just raise the price of oxygen. It's not like you can refuse to pay or buy elsewhere...

          1. elsergiovolador Silver badge

            Re: Just set the entire moon to Coordinated Universal Time (UTC +0) ...

            Make sure to patent breathing and charge a licence fee.

            1. DJV Silver badge

              Fail...

              ...due to prior art...

              1. Anonymous Coward
                Anonymous Coward

                Re: Fail...

                By whom? Ryanair?

                :)

                1. The Oncoming Scorn Silver badge
                  Coat

                  Re: Fail...

                  The Doctor reveals the limit of breaths is an algorithm to stop people "wasting" oxygen, part of the company's automated profit-making system; killing the wearers was just the logical endpoint of corporate profit over human life.

                  He hacks the station's systems to cause the station to self-destruct if they are killed, and convinces the others this is a "good death" and revenge against the corporation.

                  The computers recognise this threat to corporate profits and recalculate the suits' programming, and the zombies turn over their oxygen supplies to the survivors.

                  https://en.wikipedia.org/wiki/Oxygen_(Doctor_Who)

                  Icon - Looking for me sonic.

              2. AVR

                Re: Fail...

                Nah. No one's been breathing genuine MoonAir before. If you wanted additive-free air then you should have brought your own.

              3. Ken Shabby
                Facepalm

                Re: Fail...

                Subscription only, want to default?

            2. hplasm
              Terminator

              Re: Just set the entire moon to Coordinated Universal Time (UTC +0) ...

              COME ON, COHAAGEN! GIVE THESE PEOPLE AIR!

              Icon because..

              1. Anonymous Coward
                Anonymous Coward

                Re: Just set the entire moon to Coordinated Universal Time (UTC +0) ...

                Yes, quite an eye-popping problem..

                :)

                1. Graham Dawson Silver badge

                  Re: Just set the entire moon to Coordinated Universal Time (UTC +0) ...

                  I'm sure the solution will be a breath of fresh air and I hope we can all keep abreast of new developments.

              2. Bartholomew Bronze badge

                Re: Just set the entire moon to Coordinated Universal Time (UTC +0) ...

                Now I can't stop thinking about a three ...

                1. Anonymous Coward
                  Anonymous Coward

                  Re: Just set the entire moon to Coordinated Universal Time (UTC +0) ...

                  (I think we have veered enough off the beaten path now that someone who has not seen the first of the two Total Recall movies is going to wonder WTF we're on about :) ).

                  I liked the second one too as they changed the story just enough to keep it interesting.

                  1. Inventor of the Marmite Laser Silver badge

                    Re: Just set the entire moon to Coordinated Universal Time (UTC +0) ...

                    The original novel was better. We can remember it for you wholesale.

                2. Benegesserict Cumbersomberbatch Bronze badge

                  Re: Just set the entire moon to Coordinated Universal Time (UTC +0) ...

                  Eccentrica Gallumbits?

        3. Eclectic Man Silver badge
          Alien

          Re: Just set the entire moon to Coordinated Universal Time (UTC +0) ...

          The USA claims taxes on global earnings by its citizens, wherever they work. 'Merican Nobel laureates pay taxes on their prize money, Boris Johnson (then part USAn) had to pay tax on the profit he made on his main residence in the UK when he sold it, despite it being free of tax in the UK. I believe that ton the ISS you are bound by the laws of your home nation. So British Astronauts can gamble over the airwaves, but USA ones may not.

          The real issue with taxing people on the Moon would be determining the tax year, and sending in your completed tax return.

          Whilst, as a Brit, I wholly approve of Universal Time (aka Greenwich Mean Time) being used as the official galaxy wide time standard, that is too much hubris, even for me (but not for former PM Boris Johnson: https://www.huffingtonpost.co.uk/entry/boris-johnson-galactic-britain-twitter_uk_6152e7a9e4b001641198c6f5 ).

          Alien icon, obvs.

          1. Peter Gathercole Silver badge

            Re: Just set the entire moon to Coordinated Universal Time (UTC +0) ...

            CUT and GMT are not (quite) the same. They were, at one time, but since GMT is a sidereal time system that is actually based on the Earth's rotation, and CUT is supposed to be an absolute reference, as the Earth wobbles, they add or subtract leap-seconds to GMT (although I think I heard that they were going to stop that).

            If you do not adjust time as a result of wobble, then you face the problem that the Sun may not be exactly overhead at 12:00 noon GMT.

            It's a problem for the future, as the Earth's orbit around the Sun will change in the (very) long term. GMT will have to diverge from CUT.

            1. Elongated Muskrat

              Re: Just set the entire moon to Coordinated Universal Time (UTC +0) ...

              Where I live, the sun is exactly* overhead at about 12:12 GMT

              *I'm pretty sure it's only so on certain days of the year, as well, due to the fact the Earth is slouching in space, and won't sit up straight and stop wobbling, and I don't live on the equator.

              1. Bill Gray

                Re: Just set the entire moon to Coordinated Universal Time (UTC +0) ...

                > I'm pretty sure it's only so on certain days of the year

                You are correct. There is an 'equation of time' correction, which can cause a sundial to run about a quarter hour ahead or behind mean solar time over the course of a year. (Except for some really clever sundials, usually with an oddly-shaped gnomon or other way of correcting for this.) Thus, where I live, the Sun is due south at about 11:36 AM local time, but it can be between about 11:21 and 11:51, depending on the time of the year.

                Also, note that the sun will only pass overhead if you're in the tropics, and then only twice a year.

                1. Peter Gathercole Silver badge

                  Re: Just set the entire moon to Coordinated Universal Time (UTC +0) ...

                  I (obviously) meant directly over head in Greenwich when I was talking about GMT. And yes, I should have said "at it's highest", as Greenwich is significanty north of the equator.

            2. rmallins

              Re: Just set the entire moon to Coordinated Universal Time (UTC +0) ...

              I'm pretty sure it's TAI you're actually thinking of rather than UTC. UTC is based upon TAI. UTC has leap-seconds occasionally inserted (and theoretically removed, though that hasn't happened yet) to track the rotation of the earth. If we were to use a terrestrial timebase on the moon, TAI would probably be a better choice than UTC, because it is not linked to the rotation of the earth. Though as others here have pointed out, making a clock near the moon track TAI accurately would be a challenge. I believe that's why a new standard is being considered.

              TAI (French acronym like UTC): https://en.wikipedia.org/wiki/International_Atomic_Time

          2. katrinab Silver badge
            Alien

            Re: Just set the entire moon to Coordinated Universal Time (UTC +0) ...

            Some problems:

            If you take an atomic clock up to the moon, it won’t remain in sync with a similar clock on earth.

            I presume a lunar day isn’t anything link a terrestrial day in terms of length

            I’m not sure if the moon has any concept of a year in terms of changing seasons.

            Given that the terrestrial month sort-of relates to phases of the moon, I assume that would apply to phases of the Earth up there? It is mostly arbitrary these days down here, but maybe it could actually be really important on the moon?

            1. Inventor of the Marmite Laser Silver badge

              Re: Just set the entire moon to Coordinated Universal Time (UTC +0) ...

              A mean solar day, sunrise to sunrise etc., on the Moon, a lunar day for short, is 29.5306 Earth days. Local lunar days can vary even more than solar days on Earth, over 6 hours shorter or 7 hours longer than the mean.

        4. Primus Secundus Tertius Silver badge

          Re: Just set the entire moon to Coordinated Universal Time (UTC +0) ...

          As I understand it, any US citizen (which I am not) has to pay federal income tax wherever they are.

        5. Stork Silver badge

          Re: Just set the entire moon to Coordinated Universal Time (UTC +0) ...

          Same way as you tax seafarers. Where they live when they are on leave.

        6. Ideasource

          Re: Just set the entire moon to Coordinated Universal Time (UTC +0) ...

          Through imports and exports, as well as travel visas fees. Reinforced by threat of violence and occasional demonstration of brutality by a militaristic action alternating with withholding of humanitarian aid and intercepting other efforts to aid from outside sources.

          Same way we do it on Earth.

          Pay tribute or we'll find some way to make you a victim of targeted suffering and/or die. It's the only reason anyone ever paid taxes. High-level abstractions and conscious excuses from the oppressed don't count. Those are just the wailing of the Damned trying to normalize their suffering to get through the day.

      3. MyffyW Silver badge

        Re: Just set the entire moon to Coordinated Universal Time (UTC +0) ...

        Any reference to moonlighting that doesn't include Bruce Willis and Cybill Shepherd is suspect, in my book.

      4. Stork Silver badge

        Re: Just set the entire moon to Coordinated Universal Time (UTC +0) ...

        I thought it was tomatoes these days

    2. m4r35n357

      Re: Just set the entire moon to Coordinated Universal Time (UTC +0) ...

      Without a convenient molten iron core to moderate the "daylight", most people will be living permanently underground anyway. Remember that, galactic "colonists" and terraformers!

      1. Bartholomew Bronze badge

        Re: Just set the entire moon to Coordinated Universal Time (UTC +0) ...

        Exactly if you are mostly living under at least 5 meters (16 feet) of regolith to mimic the radiation shielding effects of earths atmosphere, does it matter what time it is ? Solar X-rays are safely absorbed (converted to heat) in the troposphere 6 to 20 km (4 to 12 miles) above out heads here on earth. It is not just earth magnetosphere that protects us.

        1. bombastic bob Silver badge
          Devil

          Re: Just set the entire moon to Coordinated Universal Time (UTC +0) ...

          Lunar Regolith is, as I understand it, a bit like cement (not nearly as much calcium though but might still work). I expect you could mix with water and make things out of it

          Or, heat it up and melt it into thick glass, even (it seems to have a lot of SiO2 in it). That might be very useful to have local materials to build with on the moon.

          1. Anonymous Coward
            Anonymous Coward

            Re: Just set the entire moon to Coordinated Universal Time (UTC +0) ...

            The first moon base is supposedly going to be built using regolith and a giant 3d printer.

    3. Dave 126 Silver badge

      Re: Just set the entire moon to Coordinated Universal Time (UTC +0) ...

      The lunar day is 24 hours and 50 minutes long. Lunar residents may find a clock tied to a lunar day convenient if their activities are affected by day / night cycles.

      ISS usually uses UTC (GMT), but the ISS crew would often switch to the Mission Elapsed Time of a visiting space shuttle to make coordinanation easier.

      Time dilation on the ISS relative to Greenwich is such that astronauts won't notice, but it has to be accounted for on GPS satellites else their accuracy is affected.

      1. alain williams Silver badge

        Re: Just set the entire moon to Coordinated Universal Time (UTC +0) ...

        That depends on what you mean by lunar day. Yes the time between the moon being 'above the same point on Earth' is 24h50m, but the time between noons on the moon is about 29½ Earth days.

        1. ThatOne Silver badge

          Re: Just set the entire moon to Coordinated Universal Time (UTC +0) ...

          Indeed, the Moon is tidally locked to Earth and thus a lunar day/night period is around 29.5 Earth days long. Which is a little too long to stay awake, so much like in our polar regions, inhabitants will simply ignore the sun and just live their normal human 24/25h day cycle. Even more easily since they will be living underground, under artificial lights.

          1. genghis_uk
            Coat

            Re: Just set the entire moon to Coordinated Universal Time (UTC +0) ...

            <quote>Indeed, the Moon is tidally locked to Earth and thus a lunar day/night period is around 29.5 Earth days long </quote>

            Bit of a bugger if you're on a day rate! Check the small print if you're off to do some lunar construction work

    4. Binraider Silver badge

      Re: Just set the entire moon to Coordinated Universal Time (UTC +0) ...

      Unfortunately, even over the cosmologically short distances from Earth to Moon, relativistic effects can be observed. Even much-closer by GPS satellites have correct for relativistic effects to generate decently accurate position information.

      So, saying sync to UTC is missing a whole bunch of thinking needed.

      An agreed terminator on the moon getting it's own time reference solves a bunch of problems that most people won't ever have.

      Setting up the right framework here would also be useful as a precendent for e.g. Mars; as-and-when we finally stop blowing each other up over lines on a map and set out to explore.

      1. bombastic bob Silver badge
        Devil

        Re: Just set the entire moon to Coordinated Universal Time (UTC +0) ...

        "saying sync to UTC is missing a whole bunch of thinking needed."

        Not if the real purpose is for humans to get a proper day/night cycle going.

        For that, just sync to a radio signal from Earth that broadcasts UTC.

        Good enough for us meatbags, anyway.

        1. Binraider Silver badge

          Re: Just set the entire moon to Coordinated Universal Time (UTC +0) ...

          But not for precision calculations, such as navigating multibillion spacecraft. Or Lunar GPS.

    5. ArrZarr Silver badge
      Mushroom

      Re: Just set the entire moon to Coordinated Universal Time (UTC +0) ...

      Can we follow that up by putting the entire Earth on UTC too?

      It's such a waste of everybody's time and resources.

      1. ibmalone

        Re: Just set the entire moon to Coordinated Universal Time (UTC +0) ...

        Meanwhile in Canberra:

        Do you want to get lunch on Friday?

        Is that twenty three hundred Friday or oh hundred Friday?

        Edit: Auckland works better, but you get the idea.

        1. ArrZarr Silver badge

          Re: Just set the entire moon to Coordinated Universal Time (UTC +0) ...

          Friday starts at 00:00 after Thursday. Assuming that UTC doesn't change, lunchtime would be 1AM on Saturday.

          I, for one, would be perfectly happy to set UTC as the International date line (without all the wiggles caused by having multiple timezones).

          1. heyrick Silver badge

            Re: Just set the entire moon to Coordinated Universal Time (UTC +0) ...

            I don't give a crap what the clock says. I just don't want to have to go to work at some dumb time in the very early morning. That's all...

            (SO not a morning person)

          2. Primus Secundus Tertius Silver badge

            Re: Just set the entire moon to Coordinated Universal Time (UTC +0) ...

            @ArrZarr

            I propose that the date line be moved to the Atlantic Ocean, specifically to longitude 30W. It would be almost entirely a straight line, except for North-East Greenland and some islands off the coast of Brazil.

            1. Elongated Muskrat

              Re: Just set the entire moon to Coordinated Universal Time (UTC +0) ...

              A straight line, when viewed from points on one plane. A curve (approximating, but not equal to, an arc) from others.

          3. ibmalone

            Re: Just set the entire moon to Coordinated Universal Time (UTC +0) ...

            Missing the point: yes Friday starts after Thursday, but both Friday 0000 UTC and Friday 2300 UTC are valid times to meet for lunch in Auckland and the sun sets and rises between them. You could talk about something being tomorrow and it still be the same calendar day, or tomorrow (calendar day) and mean just after we finish lunch. Yes, if you want to try to pick a different date line you can avoid that particular example except for people in Alaksa and Siberia, but it will still throw up nonsensical scenarios and generally mess with how people normally use the clock.

        2. HappyDog

          Re: Just set the entire moon to Coordinated Universal Time (UTC +0) ...

          You eat lunch at (or around!) midnight?

          1. Benegesserict Cumbersomberbatch Bronze badge

            Re: Just set the entire moon to Coordinated Universal Time (UTC +0) ...

            No, the sun is most up at about 2300. Don't you know that's the middle of the day?

            It's always now everywhere. (gold star)

      2. bombastic bob Silver badge
        Unhappy

        Re: Just set the entire moon to Coordinated Universal Time (UTC +0) ...

        people who have "farmer schedules" with actual day/night cycles would resist

        1. ArrZarr Silver badge

          Re: Just set the entire moon to Coordinated Universal Time (UTC +0) ...

          The only change would be that the sun rises at 16:00 rather than 04:00. The day/night wouldn't change.

      3. Tessier-Ashpool

        Re: Just set the entire moon to Coordinated Universal Time (UTC +0) ...

        When I developed a payment system for our company, I reported the emailed transaction time in UTC rather than local time. To do otherwise would yield ambiguous information a couple of days in the yearn the 1am to 2am slot.

        Company managers went ape because virtually nobody in the fairly large IT department had heard of UTC.

        1. Stork Silver badge

          Re: Just set the entire moon to Coordinated Universal Time (UTC +0) ...

          At Maersk all systems were on UTC. Only that made sense, and in shipping it is obvious.

    6. bombastic bob Silver badge
      Devil

      Re: Just set the entire moon to Coordinated Universal Time (UTC +0) ...

      Agreed. In the U.S. Navy it was called 'Zulu Time' but basically UTC +0

      Since I was on a sub there was no day/night. So after a day or so on extended deployment we'd switch over to Zulu (logs and everything), then before pulling into port switch to local time zone.

      The moon could remain at UTC +0 and it would be perfect.

    7. v13
      Trollface

      Re: Just set the entire moon to Coordinated Universal Time (UTC +0) ...

      How about DST?

  3. xyz Silver badge

    Hey Moon - your time is, like, totally dilated

    Gets worse... Because everything moving will have a different velocity and therefore have a different time. Where's Joe Haldeman when you need him.

    1. veti Silver badge

      Re: Hey Moon - your time is, like, totally dilated

      Well, that happens on Earth too, but we seem to manage somehow.

      1. that one in the corner Silver badge

        Re: Hey Moon - your time is, like, totally dilated

        > we seem to manage somehow

        by having lots and lots of wire stretched across the planet, connecting together all the systems that care about precise timing: global-scale radio interferometry, LIGO and the stock markets. With lumps of electronics carefully characterising the comms to allow for, ooh, measuring and accounting for continental drift, the occasional mountain changing the local gravity field.

        Quite a bit of work has gone into the timing systems on Earth.

  4. Neil Barnes Silver badge

    If you want to know the rate of time on the moon

    - build a cathedral

    - ensure that it contains a long pendulum

    - allow a passing polymath to observe the rate at which that pendulum swings

    - calculate the expected rate (taking into account the local gravitational field) and note the difference between the expected and observed rates

    - $

    Or, more sensibly: what's wrong with UTC?

    1. Flocke Kroes Silver badge

      Re: Problem with UTC

      For a start, anything that counts seconds will diverge from UTC. Everything with its own time keeping would need to be modified to count lunar seconds instead. The meter is defined by the distance travelled by light in a second so you get a lunar meter as well. The kilogram is safe but a whole pile of derived units get lunar versions: velocity, momentum, force, energy, power, current, voltage, angular velocity, angular momentum... You get a new temperature scale or have to use different thermodynamic constants near the moon.

      Life is actually easier if you keep the second in common and just accept that the conversion from Earth time to Moon time is not simply add a constant.

      1. Anonymous Coward
        Anonymous Coward

        Re: Problem with UTC

        The meter is defined by the distance travelled by light in a second so you get a lunar meter as well

        Nope, this is the one of the reasons why the definition of the metre was changed from the length of a metal bar (originally kept in France I believe) to the distance that light travels in vacuum in approximately a 300 millionth of a second. To an observer, light travelling in a vacuum must always travel at a velocity of c, so a metre is always exactly a metre, whatever your relativistic frame of reference is.

        Unless you're talking about space time compression (gravitational waves for example.) Then it gets really confusing...

      2. phuzz Silver badge
        Boffin

        Re: Problem with UTC

        That's not how relativity works.

        Lets pretend that there is a massive difference between the passage of time on the Earth and the Moon, such that humans could actually perceive it. Next, we make a one metre-long stick, by carefully measuring how far light travels in ~3.3ns, on both the Earth and the Moon.

        If you used a telescope to look from the Earth to the Moon the Lunar metre would appear to be too short. Conversely, someone on the moon would perceive the Earth's meter as being too long. (Unless I've got that the wrong way around).

        However, if you took both metre sticks up into orbit and put them next to each other, they would be exactly the same length.

        The SI units don't change. Our measurements of things might change, if we're in a different reference frame from the thing we're measuring.

        In reality, generally the differences are too small for humans to have to bother about them much, fortunately.

      3. Lil Endian Silver badge
        Go

        Re: Problem with UTC

        Yes! Yes and thrice yes! All will live in peace. That's a simply harmonic motion you propose +1

      4. that one in the corner Silver badge

        Re: Problem with UTC

        > Everything with its own time keeping would need to be modified to count lunar seconds

        Ah, what is a lunar second and how would it differ from the terrestrial second?

        Both would be (are already?) defined by counting a large number of the hyperfine doodads[1] in a caesium[2] fountain, which would give the same result[3] in both, indeed all, locations.

        [1] those are SI doodads

        [2] also available in chocolate; less precise (varies with milk content) but tastier

        [3] qualified by relativistic effects (hand waving away all the actual problems; see most of the other comments on this article)

      5. FrogsAndChips Silver badge

        Re: Problem with UTC

        "The kilogram is safe"

        If you meant that the value of the kilogram is linked to a physical artefact, I've got some news for you: https://www.bipm.org/en/si-base-units/kilogram

    2. Binraider Silver badge

      Re: If you want to know the rate of time on the moon

      As noted above, relativistic effects can be observed over earth-to-GPS satellite distances, and definitely over earth to moon. Sync to UTC is just not that simple.

      Unless you operate in a world where you live with such calculations it's an invisible problem to most.

    3. katrinab Silver badge

      Re: If you want to know the rate of time on the moon

      Or the stuff in Saint Sulpice, which I think was in use before pendulums were invented, and used to work out the right time to ring bells and celebrate Easter.

  5. chivo243 Silver badge
    Coat

    Moon time?

    Won't that be based on how long it takes to make one rotation like Earth? Wait, the moon doesn't rotate. So, the Light side is constantly AM and the Dark side is PM? Maybe we need to bring Pink Floyd into this discussion?

    There's an earth based atomic clock in one of these pockets...

    1. Joe W Silver badge

      Re: Moon time?

      Nope, the moon, in fact, rotates and has sunrise and sunset. It is tidally locked to Earth (likely what you had in mind), which means the same side always faces Earth - and this side can be light and dark (giving us the moon phases).

      1. jake Silver badge
        Pint

        Re: Moon time?

        Beat me to it. Have a beer :-)

    2. jake Silver badge

      Re: Moon time?

      "Wait, the moon doesn't rotate"

      Yes, it does. The rotation ("synchronous rotation") just happens to match it's orbit around the Earth, which is why we only see one side (plus a bit, for the pedants).

      1. Joe W Silver badge
        Pint

        Re: Moon time?

        Ha! I forgot about that small wobble :)

        have one -->

        1. KarMann
          Boffin

          Re: Moon time?

          No, it's called libration, not libation.

          1. Anonymous Coward
            Anonymous Coward

            Re: Moon time?

            LOL - well spotted :).

          2. phuzz Silver badge
            Pint

            Re: Moon time?

            If you have enough libation you'll have a libration all of your own :)

            1. Lil Endian Silver badge
              Pint

              Re: Moon time?

              That's a pretty pour joke :)

              1. phuzz Silver badge

                Re: Moon time?

                If you hang around my orbit, you'll plenty of those ;)

      2. Neil Barnes Silver badge

        Re: Moon time?

        I'd offer a small libation for the libration, but for some reason I don't always see the icons on this computer and today is one of those days.

        Theoretic pint ---->

        1. Lil Endian Silver badge
          Pint

          Re: Moon time?

          My temptation to assist your situation of loss of iconization preventing your offer of libation for the libration creates situation without placation!

          1. Dave559 Silver badge

            Re: Moon time?

            "Vibration!"

            1. Lil Endian Silver badge
              Pirate

              Re: Moon time?

              Location?

              --->

    3. Lil Endian Silver badge

      Re: Moon time?

      I was thinking ELO, as they have a Ticket To The Moon.

    4. chivo243 Silver badge

      Re: Moon time?

      On this date in 1973 Pink Floyd release their album "Dark Side of the Moon", since sold over 45 million copies

    5. Elongated Muskrat

      Re: Moon time?

      Okay clever-clogs, why do we have phases of the Moon then? You know, the ones that repeat every 29 days or so. I reckon we should have a word for that period of time. Let's go with "Moonth"...

      1. Lil Endian Silver badge
        Happy

        Re: Moon time?

        I really like Moonth! But you dropped a Clanger as the lunar cycle is 29.53 Earth days, so rounded would be 30.

        (I don't really think it was a wrong 'un, I just needed to use the Clanger joke!)

  6. Pascal Monett Silver badge
    Trollface

    Wait a second

    "the space community has a chance to disagree on interoperability before navigation and networking satellite systems are deployed"

    FTFY

    1. John Brown (no body) Silver badge
      Joke

      Re: Wait a second

      Of course they'll disagree!!! The entire world will take the opportunity to create a metric time system just for the Moon, doing away with all those silly multi-base calculations that cause us Earthbound timekeepers so much grief. Except for the USA, who will insist no only on retaining "traditional" units, but adjusting and fudging them to make them fit. Or maybe switch to the Trump-o-second, a value with no fixed meaning, is almost always smaller than it seems and varies most wildly up when courting lunar investments and wildly down when the tax man come a callin'

  7. Eclectic Man Silver badge
    Coat

    Ford Prefect

    "Time is an illusion, lunchtime doubly so."

    Arthur Dent: "You should send that to the Readers' Digest, they've got a page for people like you."

    HHGTTG, fit the first.

    I'll get my coat, it's the one with an electronic 'thumb' in the pocket.

    1. Fred Flintstone Gold badge

      Re: Ford Prefect

      Don't forget your towel..

      :)

    2. The Oncoming Scorn Silver badge
      Thumb Up

      Re: Ford Prefect

      I thought he kept it in his satchel.

      In all versions of the story, Ford carried around his satchel, which contained a variety of useful items. The satchel contained un-Earthly technology: a Sub-Etha Sens-O-Matic, an Electronic Thumb, and a copy of The Hitchhiker's Guide to the Galaxy. In the book, Ford's satchel also contains a couple of dog-eared scripts for plays that he pretended he was auditioning for, a few biros, a notepad, and a largish bath towel from Marks and Spencer. Ford always made sure he had his towel.

  8. Dave559 Silver badge

    Hang on a second…

    I'm confused:

    "time passes at a different rate there due to the Moon's specific gravity and velocity effects"

    […]

    "According to the ESA, a clock on the Moon gains around 56 millionths of a second per day compared to a terrestrial equivalent, and that rate changes based on whether the clock is in orbit or on the Moon's surface."

    But wouldn't one standard SI second always be one second long, no matter where you are observing it from (although the lack of elephants for counting them may be a minor concern)? Why would a standard "Earth" second be different on the Moon (I can see that 1/86400th of a lunar day would obviously be a different period of time, but that's not what we are talking about, are we)? (I'm asking as a genuine confused layman, because time can be a confusing matter.)

    Or is the issue more about calibrating your clock on the Moon with its time reference sources (eg, calculating the correct offsets from your location on the Moon to the lunar GPS satellites, as they'd be at a different orbital distance/time from your lunar location than those orbiting the Earth are from locations on Earth)?

    But I'm afraid I still don't understand how the "different rate" and "gaining several µs per day" come into being?

    1. that one in the corner Silver badge

      Re: Hang on a second…

      The issue is simply (!) that the two clocks are are apart (these seconds are very small, those are far away).

      > wouldn't one standard SI second always be one second long, no matter where you are observing it from?

      No. There is the rub.

      To observe a value, you have to have (as close to you a possible, e.g. in your hand) a suitable device for measuring that sort of value. To measure a second, you use a clock. Which just means that to measure a clock to see if it is ticking away seconds you have your own clock: two (or more) clocks are always involved, so you can just (!) ensure they are identical. That takes away lots of the arguments.

      If the two clocks are physically close together, they will tick in synchrony. The observed clock shows "seconds" as measured by your clock.

      *BUT* if you set both counters to zero (easy, as they are close together) then take one to the moon (give both clocks *really* big LED displays) and watch the lunar clock with a telescope, using the other eye to watch your own clock, they will no longer be counting at the same rate. Or you could go to the moon, taking all your kit with you - same result. As loony (ahem) as it sounds, *WHERE* you stand to make your observation actually changes the results!

      Both clocks are still working perfectly: bring the lunar one back and put it next to your clock, they will be in synchrony. BUT the total counts since they were both together won't match.

      It is one of those things that truly can bend the mind, because our built-in measurements of time passing are just not used to dealing with the tiny, tiny differences when the effects occur around us (which they do) nor are we really used to arguing over "what does it mean to say that two events are simultaneous?": in our daily evolutionary existence, the speed of light is just so fast we're happy to agree that we both saw the enormous flash at the same time, so our cups of tea were dropped simultaneously.

      The "how" and "why" are - really, really tricky :-( It would be so much easier to understand if we lived on the surface of a neutron star: then you'd see your watch changing, compated to the one on the mantelpiece, every time you stood up to change the TV channel, which is why remote controls are so quickly invented by the Cheela (see "Dragon's Egg" by Robert L. Forward, inventor of the Forward Mass Detector, a real physicist as well hard SF author).

      You can read up on Relativity (can't be *that* hard, it is over a century old now!) or just accept that Things Are Weird: clocks - time - slows down in a gravity field (so, in two different fields - Earth and Moon - one slows down more than the other, compared to, say, if they started together with a third clock at the Lagrange Point between them E&M). AND it also slows down if one clock travels faster than the other clock (like on a rocket to the Moon). Which all means that you can't [1] synchronise clocks on the Earth and the Moon, give up and have another cup of tea.

      [1] no, really. Definitely can't start them together on Earth - or anywhere else - then move them into position, one here and one there. If you try to calculate the gravitational effects and put a correction in the display of one of them, presumably one the Moon, to "tick at the same rate", good luck starting their counts at the *precise* same time!

      1. Ken Hagan Gold badge

        Re: Hang on a second…

        I don't think you are quite correct. As long as two clocks are in the same inertial frame of reference, they can be synchronised no matter what the distance. Our ability to synchronise clocks on any part of the Earth's surface depends on this, and on ignoring the very tiny acceleration of the Earth's rotation.

        As you go on to point out, the fundamental difficulty is that Earth and Moon have gravitational wells of quite differing depths and so one SI second is actually different. (Those Caesium vibrations on Earth are red-shifted as viewed from the moon.)

        Nevertheless, I suspect that denizens of the Moon will want a *calendar* that agrees with their friends and relatives on Earth and so, like on Earth, we'll end up using some awful bodge that uses atomic clocks but then screws with the numbers to approximate a solar day.

        1. that one in the corner Silver badge

          Re: Hang on a second…

          > As long as two clocks are in the same inertial frame of reference, they can be synchronised no matter what the distance

          Which is why I specified synchronising clocks on Earth with clocks on the Moon: even if they all started out together on Earth, when you move some of them to the Moon they will no longer be in sync. Earth and Moon are not the same inertial frame of reference: the Moon's orbit requires that it be constantly accelerating with respect to the Earth (more accurately, towards the Earth/Moon barycentre).

      2. Dom 3

        Re: Hang on a second…

        Obvs, the lunar timezone will be UTC, as it is on ISS. It's the only one that will get universal agreement. The Chinese will do their own thing but until the Middle Kingdom finally re-establishes itself as the pre-eminent power (I'll be dead, not sure about the offspring) they'll play along when talking to other nations.

        The headline is misleading - the issue is not about timezones, it's about establishing what the time is when clocks run at different rates.

        "You can read up on Relativity (can't be *that* hard, it is over a century old now!) " - we may have a century of literature to read but that doesn't make it any easier to comprehend.

        Maxwell's equations are older and arguably harder to derive (or remember). And actually more relevant to earth-bound life.

        We've had two *thousand* years of argument over what is now mostly known as "Trigger's broom", but was previously known as the "Ship of Theseus".

        And Plutarch was probably re-hashing a pub argument that had been going on for a fair while. My point being that something being old doesn't make it settled.

      3. John Brown (no body) Silver badge
        Thumb Up

        Re: Hang on a second…

        "No. There is the rub."

        Thanks. I tried to explain all this to my boss this morning when he said I was late for work and I said I wasn't. He didn't believe me. No I have a cogent and eloquent explanation I point him to when it next happens.

    2. Graham Cobb Silver badge

      Re: Hang on a second…

      I will admit to also finding this confusing. But I am no expert on time.

      Those who are assure us that, for example, 2 clocks at different heights on Earth keep different time. So, if you build 2 identical atomic clocks in London, say (at roughly sea level), and take one of them to the top of Mont Blanc and run it there for a while then bring it back, the two clocks will disagree about how long has passed since they were separated. So, I am absolutely sure that if you took one of the 2 clocks to the moon and back, they would be reading different elapsed time.

      This makes it very hard to communicate durations between the control room on Earth and the expedition on the moon. Saying "Run the foobar for 2.73 seconds" would result in disagreement about when it had stopped running (not actually measurable over a duration of a couple of seconds presumably, but you get the idea - it is measurable enough in low earth orbit that GPS has to take this into account, so presumably a much bigger difference when looking at the moon).

      Of course, you can avoid the disagreement by stretching or compressing the seconds (increasing or reducing the number of oscillations of the magic crystal you are using for timing, for example). But that would change the value of most "physical constants" in one of the two environments so it isn't an option.

      Although the issue isn't about "time zones" at all, it is a very real issue about how to measure and communicate time on the moon. My understanding is that Lunar time will diverge from Earth time at a rate noticeable within less than a year.

      1. Graham Cobb Silver badge

        Re: Hang on a second…

        By the way, a note on terminology... this effect is part of General Relativity and is to do with gravity, not movement. The term time dilation is usually used to refer to a completely different effect that is part of Special Relativity and is due to movement at different speeds, not gravity.

        The Wikipedia article on Time Dilation explains the difference, and discusses what happens when they both apply.

        1. Dave559 Silver badge

          Re: Hang on a second…

          Thanks, everyone, for your explanations. I still remain somewhat confused, but will (of course) continue to have faith that clever physics/astronomy-type people know what they are talking about, and not hurt my brain by trying to understand it myself!

  9. mmonroe

    We should ask The Clangers or Mr Squiggle. I assume they solved the problem years ago.

    1. Graham Cobb Silver badge

      I assume the Clangers know that the correct time is Lunar time and that they are just waiting for the Earth to change our clocks to match theirs.

    2. that one in the corner Silver badge

      The Clangers are a simple people, happy to rely on the tried and tested "however long it takes for soup to fill a bowl" timekeeping scheme. With regular adjustments for viscosity changes during the year, known as "crouton saving time".

    3. TimMaher Silver badge
      Pint

      Re:- The Clangers

      I was going to ask the man in the moon.

      And get some cheese whilst there.

  10. SonofRojBlake

    "a three-dimensional point that sets a physical standard from which to measure universal time"

    That's one thing everyone should be able to agree on, surely? Tranquility Base has to be that point, doesn't it? (Along with the museum that will eventually be built around it...)

  11. MacroRodent

    Timey wimey

    The time dilatation effect is actually surprisingly large. If a clock on the Moon gains 5.6e-5 seconds per day, it takes only around 49 years to gain a whole day.

    This will mess up birthday celebrations...

    1. Elongated Muskrat

      Re: Timey wimey

      It's okay, the lunar day is much longer than ours, and I don't think Clangers live long enough to feel the effect.

    2. anthonyhegedus

      Re: Timey wimey

      No, that's 56 millions of a second PER DAY. So it will gain 0.02 seconds per year, 2 seconds in 100 years, and 1 day in 42000 years. You were thinking of 56 millionths of a second per second.

      1. MacroRodent

        Re: Timey wimey

        You are right, a crude error on my part.

  12. AndrueC Silver badge

    Where will the date line be placed? Given the tidal locking presumably it'll have to be a moving line.

    1. dancecat

      On the other side of the moon from wherever Lunar Britain is founded.

  13. HappyDog

    Daylight saving?

    My biggest beef is that every year (twice!) we go through Daylight Saving. One hour forward, one hour back. Here in Ireland, we go back an hour in October and forward an hour in March. Why March? If we go back one hour one month after the autumn (fall for our American cousins) equinox, why do we have to wait until one week after the Spring equinox before we get that hour back? By my reckoning we could have put the clocks forward last Sunda. Meaning we could be having daylight until 7pm and beyond from now on

    1. Yet Another Anonymous coward Silver badge

      Re: Daylight saving?

      > One hour forward, one hour back

      That's your mistake. If you keep moving just forward then you will gradually move into the future and eventually get flying cars!

    2. John Brown (no body) Silver badge
      Coat

      Re: Daylight saving?

      If we "bank" an hour and then get it back 6 months later, what is the interest rate and when do I get my share?

  14. lukewarmdog
    Pint

    Just make it 5PM Everywhere and All The Time

    https://en.wiktionary.org/wiki/it%27s_five_o%27clock_somewhere

  15. tyrfing

    Use UTC. Sorted. This is a silly controversy.

    Time zones started because of train schedules - you had to know when the train was leaving your local station. The schedules looked funny in California if they all used Chicago time, but you couldn't have a local time for each station. So a compromise was worked out with zones which all had the same time.

    The Moon has a roughly one month day-night cycle, so you might as well use one time zone for the whole thing since you're not setting schedules by how light or dark it is.

    Setting a unique time zone for the Moon would just mean looking up one more table. Why make things that much more complex?

    1. Dizzy Dwarf

      I guess that Tranquility Base underground station would be in zone 7.

    2. Dom 3

      "The schedules looked funny in California if they all used Chicago time, but you couldn't have a local time for each station."

      Historically, "s/California/Bristol/" and "s/Chicago/London/".

      OSLT.

    3. MrZoolook

      "The schedules looked funny in California"

      Everything... EVERYTHING looks funny in California.

      Possibly because everything causes cancer in California. But I'd argue it's more likely that California IS a cancer infecting everything in it, making those schedules look funny.

      1. jake Silver badge

        "EVERYTHING looks funny in California."

        Sez the Londoner who has probably never even traveled as far as Hull.

  16. Horizontal

    UTC

    ZULU ÷ M

    Simple really

  17. -tim
    Coat

    Wasn't this solved decades ago?

    There have been hacks to the timezone files used by Unix/Linux/OSx to adjust for moon time and solar noon time.

    One odd advantage of the leap second is that now some programmers understand that the concept of time in computers isn't quite as easy as it first appears.

    1. TimMaher Silver badge
      Facepalm

      Re: Wasn't this solved decades ago?

      Not to mention the Y2K debacle and that thing with older GPS.

  18. Big_Boomer Silver badge

    Agreement? <LOL>

    The US Moonbase will run on Houston time, the Chinese Moonbase will run on Beijing time, the Russian Moonbase will run on Moscow time, the EU Moonbase will run on Brussels/Strasbourg time, and the UK Moonshack will run on GMT of course. Since almost all Loonies of whatever extraction will be living underground, what does it matter what time it is so long as they refer to an agreed time/date standard, just like down here? It's not like they need to get up at "dawn" to work the farm. It sounds to me like some of you need to go and read/re-read The Moon is a Harsh Mistress.

    1. John Brown (no body) Silver badge
      Windows

      Re: Agreement? <LOL>

      "and the UK Moonshack will run on GMT"

      You mean the mock-up at the Leicester National Space Centre still awaiting a launch opportunity and funding decades after Tuvalu have moved their entire population somewhere a bit drier and well above sea level, such as the Sea of Tranquillity?

      Represents the UK space programme ---------------------->

  19. David Hicklin Bronze badge

    LunaNet - the first true IPv6 network?

    Seeing as there are no free big IPv4 blocks to allocate.

  20. Spherical Cow

    Metric time

    This seems like the perfect opportunity to introduce a metric time counting system to be used in all extraterrestrial colonies. Although I'm impressed with the Sumerians' ability to count in base 60, base 10 is all the rage these days.

  21. Grinning Bandicoot

    Now children Arthur Clark has already covered the question in one of his 40's short story [again it might be later when plan Sri Lanka move] where the British contingent elects to remain behind on the moon after other depart thereby depriving Internal Revenue. In The Moon is a Harsh Mistress the local domes ran on their local times and travelers just made due. But the real question was adapting a time frame to the moon and then a coordinated time base. Much ado about nothing! Construct the time base clock to work unattended in moon conditions, then launch. Where it lands then becomes the Prime Meredian of the Moon

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