diff --git a/lib/libc/time/Theory b/lib/libc/time/Theory index 0149117035d5..4a90eb6a343d 100644 --- a/lib/libc/time/Theory +++ b/lib/libc/time/Theory @@ -1,5 +1,5 @@ -# $NetBSD: Theory,v 1.7 2003/12/20 00:12:05 kleink Exp $ -@(#)Theory 7.14 +# $NetBSD: Theory,v 1.8 2004/05/27 20:39:49 kleink Exp $ +@(#)Theory 7.15 ----- Outline ----- @@ -8,6 +8,7 @@ Names of time zone regions Time zone abbreviations Calendrical issues + Time and time zones on Mars ----- Time and date functions ----- @@ -505,3 +506,48 @@ convert to the Gregorian calendar until the Soviet revolution of 1917. Source: H. Grotefend, _Taschenbuch der Zeitrechnung des deutschen Mittelalters und der Neuzeit_, herausgegeben von Dr. O. Grotefend (Hannover: Hahnsche Buchhandlung, 1941), pp. 26-28. + + +----- Time and time zones on Mars ----- + +Some people have adjusted their work schedules to fit Mars time. +Dozens of special Mars watches were built for Jet Propulsion +Laboratory workers who kept Mars time during the Mars Exploration +Rovers mission (2004). These timepieces look like normal Seikos and +Citizens but use Mars seconds rather than terrestrial seconds. + +A Mars solar day is called a "sol" and has a mean period equal to +about 24 hours 39 minutes 35.244 seconds in terrestrial time. It is +divided into a conventional 24-hour clock, so each Mars second equals +about 1.02749125 terrestrial seconds. + +The prime meridian of Mars goes through the center of the crater +Airy-0, named in honor of the British astronomer who built the +Greenwich telescope that defines Earth's prime meridian. Mean solar +time on the Mars prime meridian is called Mars Coordinated Time (MTC). + +Each landed mission on Mars has adopted a different reference for +solar time keeping, so there is no real standard for Mars time zones. +For example, the Mars Exploration Rover project (2004) defined two +time zones "Local Solar Time A" and "Local Solar Time B" for its two +missions, each zone designed so that its time equals local true solar +time at approximately the middle of the nominal mission. Such a "time +zone" is not particularly suited for any application other than the +mission itself. + +Many calendars have been proposed for Mars, but none have achieved +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 +documented here in the hopes that support will be added eventually. + +Sources: + +Michael Allison and Robert Schmunk, +"Technical Notes on Mars Solar Time as Adopted by the Mars24 Sunclock" + (2004-03-15). + +Jia-Rui Chong, "Workdays Fit for a Martian", Los Angeles Times +(2004-01-14), pp A1, A20-A21. diff --git a/lib/libc/time/tz-link.htm b/lib/libc/time/tz-link.htm index 541a69a0f181..0e6307300709 100644 --- a/lib/libc/time/tz-link.htm +++ b/lib/libc/time/tz-link.htm @@ -9,7 +9,7 @@ - + @@ -19,7 +19,7 @@

Sources for Time Zone and Daylight Saving Time Data

-@(#)tz-link.htm 7.41 +@(#)tz-link.htm 7.42

Please send corrections to this web page to the @@ -99,8 +99,8 @@ Here are some recent links that may be of interest.

Web pages using recent versions of the tz database