Time zone

::Time Zone is also a historical computer game.

Related Topics:
Time Zone - Computer game

~ ~ ~ ~ ~ ~ ~ ~ ~ ~

::There is also an Australian franchise of video arcades called Timezone.

Related Topics:
Australia - Franchise - Video arcade - Timezone

~ ~ ~ ~ ~ ~ ~ ~ ~ ~

Time zones are areas of the Earth that have adopted the same standard time, usually referred to as the local time. Formerly, people used local solar time (originally apparent and then mean solar time), resulting in time differing slightly from town to town. With the expansion of the railways and as telecommunications improved this became increasingly awkward. Time zones partially rectified the problem by setting the clocks of a region to the same mean solar time. Time zones are generally centered on meridians of a longitude, that is a multiple of 15° (360°/24 hours), thus making neighboring time zones one hour apart. However, the one hour separation is not universal and, as the map below shows, the shapes of time zones can be quite irregular because they usually follow the boundaries of states, countries or other administrative areas.

Related Topics:
Earth - Time - Solar time - Town - Railways - Telecommunication - Meridian - Longitude

~ ~ ~ ~ ~ ~ ~ ~ ~ ~

All time zones are defined relative to Coordinated Universal Time (UTC). The reference point for Time Zones is the Prime Meridian (longitude 0°) which passes through the Royal Greenwich Observatory in Greenwich, London, United Kingdom http://greenwichmeantime.com/. For this reason the term Greenwich Mean Time (GMT) is still often used (by the BBC, for example, amongst others) to denote the "base time" to which all other time zones are relative. UTC is, nevertheless, the official term for today's atomically measured time as distinct from time determined by astronomical observation as formerly carried out at Greenwich.

Related Topics:
Coordinated Universal Time - Prime Meridian - Longitude - Royal Greenwich Observatory - Greenwich - London - United Kingdom - Greenwich Mean Time - GMT - BBC

~ ~ ~ ~ ~ ~ ~ ~ ~ ~

GMT (UTC) is, incidentally, local time at Greenwich itself only between 01:00 UTC on the last Sunday in October and 01:00 UTC on the last Sunday in March. For the remainder of the year local time is UTC + 1, known in the UK as British Summer Time (BST).

Related Topics:
UK - British Summer Time

~ ~ ~ ~ ~ ~ ~ ~ ~ ~

The time for a location is given relative to UTC. Some examples:

~ ~ ~ ~ ~ ~ ~ ~ ~ ~

• Los Angeles, California, USA: UTC − 8 (e.g. if it is 12:00 UTC, then it is 04:00 in Los Angeles)
• Toronto, Ontario, Canada: UTC − 5 (e.g. if it is 12:00 UTC, then it is 07:00 in Toronto)
• Stockholm, Sweden: UTC + 1 (e.g. if it is 12:00 UTC, then it is 13:00 in Stockholm)
• Istanbul, Turkey: UTC + 2 (e.g. if it is 12:00 UTC, then it is 14:00 in Istanbul)
• Mumbai, India: (e.g. if it is 12:00 UTC, then it is 17:30 in Mumbai)
• Tokyo, Japan: UTC + 9 (e.g. if it is 12:00 UTC, then it is 21:00 in Tokyo)

Where the adjustment for time zones results in a time the other side of midnight from UTC, then the date at the location is one day later or earlier. Some examples:

~ ~ ~ ~ ~ ~ ~ ~ ~ ~

• Cairo, Egypt: UTC + 2 (e.g. if it is 23:00 UTC on Monday 15 March, then the time in Cairo is 01:00, Tuesday 16 March)
• Auckland, New Zealand: UTC + 12 (e.g. if it is 21:00 UTC on Wednesday 30 June, then the time in Auckland is 09:00, Thursday 1 July)
• New York, USA: UTC − 5 (e.g. if it is 02:00 UTC on Tuesday, then the time in NY is 21:00 on Monday)
• Honolulu, Hawai'i, USA: UTC − 10 (e.g. if it is 06:00 UTC on Monday 1 May, then the time in Honolulu is 20:00, Sunday 30 April)

Note: The time zone adjustment for a specific location may vary due to the use of daylight saving time.

~ ~ ~ ~ ~ ~ ~ ~ ~ ~

• e.g. New Zealand which is usually UTC + 12, observes a one-hour daylight saving time adjustment during the southern hemisphere summer, resulting in a local time of UTC + 13!

See also: Sidereal time Calculating local time

Related Topics:
Sidereal time - Calculating local time

~ ~ ~ ~ ~ ~ ~ ~ ~ ~

 
Time zone: History ►