Time Zones

http://www.worldtimeserver.com/
http://www.worldtimezone.com/
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The "Gnome clock" and "KDE clock" applets each show a window in real time on your desktop, including night and day shadows.

Time zones, as of Sunday 30 March 2008, where some of us are at:

  • New York, USA UTC -4 hours
  • St. John's, Canada UTC -2.30 hours
  • Sao Paulo UTC, Brazil -3 hours
  • Montevideo, Uruguay UTC -3 hours
  • Central Europe UTC +2 hours
  • Brisbane, Queensland, Australia UTC +10 hours (DST)

In the Northern hemisphere DST (Daylight Saving Time) starts on Sunday, March 30, 2008 at 2:00 AM local ST (Standard Time) and ends on Sunday, October 26, 2008 at 3:00 AM local daylight time.

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GMT:
Greenwich Mean Time
* a mathematical mean, defined in terms of the solar second
* the mean solar time of the Prime Meridian (zero degree longitude)
* measured at the former location of the Royal Observatory in Greenwich, London
* the Royal Observatory was created in 1675 to help sailors calculate time at sea
* GMT is useful for navigation (used by commercial pilots worldwide) but not for time-keeping programs.
* When speaking loosely, GMT and Coordinated Universal Time (UTC) are roughly the same, but careful speakers will note that GMT is based on the solar second, while UTC is based on the standard second.
* called Zulu time in the military and international radio communication
* used for most meteorological (weather) applications and activities
* in e-mail headers you will often see references to the hours offset from GMT
* theoretically, noon Greenwich Mean Time is the moment when the Sun crosses the Greenwich meridian (and reaches its highest point in the sky in Greenwich)

UTC:
Coordinated Universal Time
* An atomic realization of Universal Time or GMT.
* A time standard that is not affected by time zones or seasons.
* since 1986 the official time reference for the world
* Since unanimous agreement could not be achieved on using either the English word order abbreviation, CUT, or the French word order abbreviation, TUC, the acronym UTC was chosen as a compromise.
* maintained by the US Naval Observatory.
* GMT is measured from noon whereas UTC is measured from midnight. However, few use the noon measurement and refer to GMT as if it were actually UTC.

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