Re: Paging Neil
> "an Earth-based clock observed by someone on the Moon that would appear to lose an average of 58.7 milliseconds per Earth day"
> I'm a little confused by the "observed" part though. Doesn't the "observation" also have to make the trip?
The light used to make the observation will also take time to travel from Earth to the Moon, and that time will also vary as the Earth rotates, the Moon orbits, that orbit recedes etc etc.
But when a clock is constantly losing (or gaining) you don't need to observe it frequently to observe the effect - you can imagine[1] waiting a few of years between peeking at the timepieces, measuring the distance[2] between Moon and Earth at the point of each clock observation to compensate. Then you'll see the cumulative drift and can point out that this is way outside the combined error bars for the two observations, so celebrate down the pub lads.
Whether or not the drift makes a genuine difference to performing any day to day operations, worth enshrining in a Lunar Time Zone, is another matter.
And from whose point of view does this new time zone actually work?[3]
After all, the astronaut's watches (and caesium clocks) will automatically convert themselves to tick at the local rate as soon as they arrive on site, so measuring durations in experiments will give the same results on Earth and Moon.
Differences in astronomical observations? Umm, tricky - I'll have to drink more coffee before trying to think that one through (do pulsars tick at different absolute rates from different observation sites? Gibber!)
[1] as good physicists do
[2] ok, just keep the round trip time and divide by two to get the adjustment for the observation - and none of your "that doesn't truly measure the one way trip time"!
[3] yes, I know that syncing actions between systems on the Moon needs to be done locally, but by the time you need the precision the clocks to give the reference will be in situ and that whole setup will be decoupled from Earth-based time. The whole concept of time zones is only relevant between two distinct locations and here we are discussing Earth versus Moon, not even separate locations across the Moon.