News and findings about our cosmos.
Subcommunity of Science
This community's icon was made by Aaron Schneider, under the CC-BY-NC-SA 4.0 license.
As a software developer, the last thing I want to see is another obscure timezone to deal with. It does seem like it'd be important to set a standard here though, and it's unlikely to affect most software engineers anyway unless we start seeing colonization at some point.
Also, in general, I can't imagine how relativity will work with this kind of timezone conversion.
Relativity is exactly the problem, time runs at a different speed on the moon. I have no idea how this is supposed to be handled in software.
Like if you have a lunar instant of time and an earth time and you want to figure out how much time happened between those two instants, I guess you'll essentially need to decide on a frame of reference and then take into account relativity as you convert the lunar time to UTC. But I'm not a physicist, I'm not sure if doing that even makes sense.
Time passes differently for other lower orbit satellites as well. They just adjust the time to take up the slack but it's likely done at very high precision.
Honestly, it should be really easy to figure out. Take two sycronized high precision clocks, put one in orbit and keep one on earth and then subtract one time from another after a few days. (At that precision, you also need to take into account the time it takes to radio the signal back to earth as well.)
The main issue comes from someone trying to build a library for this. For example, try answering the question "what time was it 2y 46d 2h 15m ago on the moon in lunar time?" (assuming it was asked on Earth, in some known timezone). Needing to look up from some table on a time server to answer all these questions sounds like a nightmare.
On Earth, there is a table with leap seconds... and sometimes they're negative. That alone, is a good reason why writing time libraries is better left to people who specialize in writing time libraries.
The relativity part, also made me think: Luna orbits Earth at about 3600Km/h... but Earth's equator itself, "orbits" Earth's poles at 1600Km/h... so if one has relativity effects on time, half that speed must be having some relativity effects too, right...? Someone on the South Pole would also see a clock on the equator go some microseconds slower per day... and all the clocks at different latitudes, and everyone relative to everyone else, so you can't tell "precisely" the time on Earth without taking into account the exact location... 😬
Just use accelerometers to measure specific gravity and have time be a function of that measurement. Problem solved!
If it was that easy, I don't think the US government would have mandated a whole project to figure it out. NASA would have done it by now and been using it internally for a while before anybody noticed.
That's not sarcasm - that's kinda how NASA solves weird (to baselines) problems like this. They just sort of do it, it's done, and then somebody might get around to publishing a paper about it. At least in the years I worked there (GSFC, 2010-2013) it used to be a thing that engineers would chat about while waiting for the coffee maker to finish brewing a fresh pot, or maybe doodle on a bad while waiting for a run to finish.
Oh god.
My service went down at timestamp x
This message looks like a potential root cause and has a lunar origin
the lunar box reports sending a message to me at timestamp y
the relay station reports relaying said message from the lunar box at timestamp z
Can you confirm the lunar message was sent at the right time to have been the cause?
Do the logs on the lunar box come timestamped with a "helpful" string representation? If they're in unix epoc, is that time dilation adjusted?
How do satellites do it, I wonder?
Makes you realize how UTC is not really universal but bound to the earth.
Of course. But there is no reason Lunar time couldn’t be kept as UTC.
It all has to do with how we perceive time and humans are notoriously bad at it (most people seem to hate the idea that 12pm could mean middle of the night…they must have 12pm equal to sun high in the sky).
For the moon, though, the only issue would be with how UTC is calculated on the surface of Earth, which will have a time offset to play in with respect to the moon, in order to keep in sync with Earth-UTC (similar to how electronic satellites like GPS have to calculate).
You could but you would need to redefine the second, no? I mean time runs slower on the Earth than the moon, so yes you could synchronise the moon to UTC but then one second of UTC goes by on the Earth but 1.0...01 second actually goes by on the Moon.
Unless you kept syncing up your clock, you'd soon find that Earth's 13:42 is actually your 13:43.
Yes, I said this in my post. Satellites do it, there’s no reason it can’t be done on the moon as well to keep in sync with Earth UTC. It’s math and physics — a problem that has already been solved.
"[...] instructed the space agency to work with other parts of the U.S. government to devise a plan by the end of 2026 for setting what it called a Coordinated Lunar Time (LTC)."
You people just hate acronyms that make sense, don't you
I'm guessing it's to stay standardised with the UTC terminology.
It’s because the French and the English can’t allow the other to win, so we use a third option
yet another item on the list of things I blame the French for
They didn't want it to be pronounced clit? Shoulda called it lunar coordinated time.
stardates here we come!
At least we won't have any dang countries forcing time zones there to be in odd shapes.
Just wait until every country’s base uses its own capital’s time. The time zones won’t even be in vague order around the moon like they generally are on earth but distributed randomly based on whatever country has the biggest base in the area.
Worse, if different countries bases and teams are using different home time zones than you don’t even have time zones. Two people from different countries in the same room could be different time zones, purely based on the country they work for.
If this fails and everyone with a space program can’t agree to just use the same standard, then time zones could get very, very bad in the future.
How do they handle this on ISS