Unearthly time zone in the news
"Moon Standard Time? Nasa to create lunar-centric time reference system: Space agency tasked with establishing Coordinated Lunar Time, partly to aid missions requiring extreme precision" Not to be missed: the opportunity to have neap seconds. @dashdashado https://www.theguardian.com/science/2024/apr/02/moon-nasa-coordinated-lunar-...
On 2024-04-02 22:16, Arthur David Olson via tz wrote:
https://www.theguardian.com/science/2024/apr/02/moon-nasa-coordinated-lunar-...
Thanks for the heads-up. There seems to be no acknowledgment in the White House press release of a similar effort launched by the European Space Agency last year, and the Guardian missed the boat on reporting on whether there are now two competing efforts to specify time on the Moon. I hope we are not going back to the bad old days, when France's prime meridian differed from Germany's. Anyway, for now I installed the attached proposed patch. If anyone knows about efforts to coordinate European and American timescales on the Moon, please let us know.
Issue: there isn't a UN M.49 code that covers this region. Steven On Wed, Apr 3, 2024 at 12:37 PM Paul Eggert via tz <tz@iana.org> wrote:
On 2024-04-02 22:16, Arthur David Olson via tz wrote:
https://www.theguardian.com/science/2024/apr/02/moon-nasa-coordinated-lunar-...
Thanks for the heads-up. There seems to be no acknowledgment in the White House press release of a similar effort launched by the European Space Agency last year, and the Guardian missed the boat on reporting on whether there are now two competing efforts to specify time on the Moon. I hope we are not going back to the bad old days, when France's prime meridian differed from Germany's.
Anyway, for now I installed the attached proposed patch. If anyone knows about efforts to coordinate European and American timescales on the Moon, please let us know.
Steven R. Loomis wrote:
Issue: there isn't a UN M.49 code that covers this region.
There is, however, a MARC 21 geographic code: [zmo]. https://www.loc.gov/marc/geoareas/gacs_code.html Yes, I do understand the incongruity of using the term “geographic” to refer to extraterrestrial locations. -- Doug Ewell, CC, ALB | Lakewood, CO, US | ewellic.org
On Apr 3, 2024, at 13:36, Paul Eggert via tz <tz@iana.org> wrote:
On 2024-04-02 22:16, Arthur David Olson via tz wrote:
https://www.theguardian.com/science/2024/apr/02/moon-nasa-coordinated-lunar-...
Thanks for the heads-up. There seems to be no acknowledgment in the White House press release of a similar effort launched by the European Space Agency last year, and the Guardian missed the boat on reporting on whether there are now two competing efforts to specify time on the Moon. I hope we are not going back to the bad old days, when France's prime meridian differed from Germany's.
Here are the full press releases from OSTP. There are actually two: White House Office of Science and Technology Policy Releases Celestial Time Standardization Policy https://www.whitehouse.gov/ostp/news-updates/2024/04/02/white-house-office-o... Policy on Celestial Time Standardization in Support of the National Cislunar Science and Technology (S&T) Strategy https://www.whitehouse.gov/wp-content/uploads/2024/04/Celestial-Time-Standar... Additionally, the Cislunar Technology Strategy Interagency Working Group's strategy paper from November 2022: https://www.whitehouse.gov/wp-content/uploads/2022/11/11-2022-NSTC-National-... /dale
On 4/3/24 13:14, Michael H Deckers via tz wrote:
..and both use LTC as abbreviation for Coordinated Lunar Time, not CLT.
Thanks for catching that. I updated theory.html accordingly. I presume that, just as "UTC" doesn't stand for either the English "Coordinated Universal Time" nor the French "temps universel coordonné", the abbreviation "LTC" was chosen because it stands for neither the English "Coordinated Lunar Time" nor (if I have it correctly) the French "temps lunaire coordonné". Or maybe they just exchanged "U" and "L" without thinking about it. The "U" in "UTC" is completely inflated of course. It's no more "Universal" than the World Series is a world-wide contest. It should be "ETC" for "Coordinated Earth Time" or "temps terrestre coordonné".
On Wed 2024-04-03T13:41:16-0700 Paul Eggert via tz hath writ:
The "U" in "UTC" is completely inflated of course. It's no more "Universal" than the World Series is a world-wide contest.
Universal Time derives from the 1884 International Meridian Conference where the delegates agreed on a Universal Day. In the late 19th century the meaning of universal was everyone in the world, not more than that. Universal Time is the subdivision of the Universal Day which was resolved to be a mean solar day. (It could have been worse, they could have adopted a different trendy word for everyone in the world like "Catholic Time". The IMC did discuss using Rome or Jerusalem as the prime meridian.) Simon Newcomb attended the IMC until US Department of State kicked him out for comments on the practical issues of defining a prime meridian. A decade later astronomers from countries producing almanacs for navigation all agreed to use Newcomb's expressions for the motion of the earth and sun. The result was every nation agreeing to Universal Time for almanacs. Ironically, as soon as that agreement went into effect the place over which the mean sun stands at 12:00 Universal Time began an increasing deviation eastward from Greenwich. Now the value of UT1 continues to increase its difference from the value of the mean solar time at Greenwich Observatory, but this becomes irrelevant as UTC without leap seconds will abandon close connection with the sun and deviate 365.25 times faster from Greenwich. -- Steve Allen <sla@ucolick.org> WGS-84 (GPS) UCO/Lick Observatory--ISB 260 Natural Sciences II, Room 165 Lat +36.99855 1156 High Street Voice: +1 831 459 3046 Lng -122.06015 Santa Cruz, CA 95064 https://www.ucolick.org/~sla/ Hgt +250 m
On 2024-04-03 22:51, Steve Allen via tz wrote:
Ironically, as soon as that agreement went into effect the place over which the mean sun stands at 12:00 Universal Time began an increasing deviation eastward from Greenwich.
Yes, and it's also ironic that although the ITRF2020 definition of the prime meridian has reached new levels of accuracy (about 1 mm at the equator![1]), that meridian currently passes about 100 meters east of the Airy Transit Circle at Greenwich. Although there are good reasons[2] for the 100 meter discrepancy, this can all be pretty confusing to amateurs such as myself. [1]: Altamimi Z, Rebischung P, Collilieux X, Métivier L, Chanard K. ITRF2020: an augmented reference frame refining the modeling of nonlinear station motions. J Geod 97, 47 (2023). https://doi.org/10.1007/s00190-023-01738-w [2]: Malys S, Seago JH, Pavlis NK, Seidelmann PK, Kaplan GH. Why the Greenwich meridian moved. J Geod 89, 1263–1272 (2015). https://doi.org/10.1007/s00190-015-0844-y
participants (7)
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Arthur David Olson -
Dale Ghent -
Doug Ewell -
Michael H Deckers -
Paul Eggert -
Steve Allen -
Steven R. Loomis