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October 2017

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[PATCH] Mention time on Mercury, Venus, etc.
by Paul Eggert Oct. 1, 2017

Oct. 1, 2017

* Theory: Mention time on planets in our solar system other than Earth and Mars, and cite Williams 2017. --- Theory | 21 +++++++++++++++++++-- 1 file changed, 19 insertions(+), 2 deletions(-) diff --git a/Theory b/Theory index b223935..3e88173 100644 --- a/Theory +++ b/Theory @@ -810,7 +810,7 @@ Mittelalters und der Neuzeit_, herausgegeben von Dr. O. Grotefend (Hannover: Hahnsche Buchhandlung, 1941), pp. 26-28. ------ Time and time zones on Mars ----- +----- Time and time zones on other planets ----- Some people's work schedules use Mars time. Jet Propulsion Laboratory (JPL) coordinators have kept Mars time on and off at least since 1997 @@ -844,7 +844,20 @@ wide acceptance. Astronomers often use Mars Sol Date (MSD) which is a sequential count of Mars solar days elapsed since about 1873-12-29 12:00 GMT. -The tz database does not currently support Mars time, but it is +In our solar system, Mars is the planet with time and calendar most +like Earth's. On other planets, Sun-based time and calendars would +work quite differently. For example, although Mercury's sidereal +rotation period is 58.646 Earth days, Mercury revolves around the Sun +so rapidly that an observer on Mercury's equator would see a sunrise +only every 175.97 Earth days, i.e., a Mercury year is 0.5 of a Mercury +day. Venus is more complicated, partly because its rotation is +slightly retrograde: its year is 1.92 of its days. Gas giants like +Jupiter are trickier still, as their polar and equatorial regions +rotate at different rates, so that the length of a day depends on +latitude. This effect is most pronounced on Neptune, where the day is +about 12 hours at the poles and 18 hours at the equator. + +Although the tz database does not support time on other planets, it is documented here in the hopes that support will be added eventually. Sources: @@ -860,6 +873,10 @@ Jia-Rui Chong, "Workdays Fit for a Martian", Los Angeles Times Tom Chmielewski, "Jet Lag Is Worse on Mars", The Atlantic (2015-02-26) <https://www.theatlantic.com/technology/archive/2015/02/jet-lag-is-worse-on-…> +Matt Williams, "How long is a day on the other planets of the solar +system?" <https://www.universetoday.com/37481/days-of-the-planets/> +(2017-04-27). + ----- This file is in the public domain, so clarified as of 2009-05-17 by -- 2.7.4

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