"Frans W. MAES" wrote: > I think you are one hour off here. In the simple case of 24 time > zones at 1 hour intervals, and an IDL between two of them, we have > the following situation. > > Consider the time zone directly west of the IDL. Here a new day is > born. Twenty-three hours later it is born in the time zone directly > east of the IDL. There it lives for another 24 hours. So its life span > is 47 hours, not 48.
Twenty-three hours after the 'birth' of a day in the time zone immediately to the West of the IDL, the previous day still has a whole hour to live in the time zone immediately to the East of the IDL. Try to visualize it for yourself in a schematic drawing. Each given calendar day thus 'lives' for 48 hours when summertime corrections are neglected, not 47! > As it says on http://tycho.usno.navy.mil/tzones.html: > > "... nations are sovereign powers that can and do change their > timekeeping systems as they see fit." > > Nevertheless, they link a map of world time zones: > > http://aa.usno.navy.mil/AA/faq/docs/world_tzones.html, > > as of July 1998. Time zones run from UT-12 to UT+14 there, which > would make the life span of a day 26+24=50 hours. In case the > UT+14 people choose to introduce DST, we even get at 51 hours > for part of the year. Now you are contradicting yourself, as you earlier claimed that an ordinary calendar day only lives 47 hours and now you are implicitly assuming that it lasts 48 hours. I had not considered the fact that a few Mid-Pacific islands appear to adopt a time zone of UT+14h. If they would for reasons of their own want to adopt DST, then, as Frans pointed out, a calendar day would last 51 hours for a part of the year. Should a leap second be introduced during that period, one calendar day would even last 183601 seconds. However, I doubt whether these islands are assigned to the right time zone. The islands as shown on the world time zone map quoted above appear to be part of Kiribati, which since 1 January 1995 adopts a time zone of UT+12h. Note that most official world time zone maps (like the one quoted above) seem to be slow in adopting the Kiribati excursion of the IDL which has been in force now for some 5½ years. ======================================================== * Robert H. van Gent * Tel/Fax: 00-31-30-2720269 * * Zaagmolenkade 50 * * * 3515 AE Utrecht * E-mail: [EMAIL PROTECTED] * * The Netherlands * * ******************************************************** * Home page: http://www.phys.uu.nl/~vgent/homepage.htm * ========================================================
