Hawaii-Aleutian time zone
Encyclopedia
Coordinated Universal Time
Coordinated Universal Time is the primary time standard by which the world regulates clocks and time. It is one of several closely related successors to Greenwich Mean Time. Computer servers, online services and other entities that rely on having a universally accepted time use UTC for that purpose...
(UTC−10). The clock time in this zone is based on the mean solar time of the 150th meridian west
150th meridian west
The meridian 150° west of Greenwich is a line of longitude that extends from the North Pole across the Arctic Ocean, North America, the Pacific Ocean, the Southern Ocean, and Antarctica to the South Pole....
of the Greenwich Observatory.
The zone takes its name from the two areas it includes: Hawaii
Hawaii
Hawaii is the newest of the 50 U.S. states , and is the only U.S. state made up entirely of islands. It is the northernmost island group in Polynesia, occupying most of an archipelago in the central Pacific Ocean, southwest of the continental United States, southeast of Japan, and northeast of...
and the portion of Alaska
Alaska
Alaska is the largest state in the United States by area. It is situated in the northwest extremity of the North American continent, with Canada to the east, the Arctic Ocean to the north, and the Pacific Ocean to the west and south, with Russia further west across the Bering Strait...
's Aleutian Islands west of 169° 30′ W longitude.
During DST
Daylight saving time
Daylight saving time —also summer time in several countries including in British English and European official terminology —is the practice of temporarily advancing clocks during the summertime so that afternoons have more daylight and mornings have less...
the Alaskan portion observes HADT
Hawaii-Aleutian Daylight Time
The Hawaii-Aleutian Time Zone observes Hawaii-Aleutian Daylight Time , by subtracting nine hours from Coordinated Universal Time . The clock time in this zone is based on the mean solar time of the 150th meridian west of the Greenwich Observatory....
while Hawaii does not.
From 1900 until 1947, GMT−10:30 was used as standard time
Standard time
Standard time is the result of synchronizing clocks in different geographical locations within a time zone to the same time rather than using the local meridian as in local mean time or solar time. Historically, this helped in the process of weather forecasting and train travel. The concept...
in Hawaii. http://www.twinsun.com/tz/tz-link.htm
French Polynesia
French Polynesia
French Polynesia is an overseas country of the French Republic . It is made up of several groups of Polynesian islands, the most famous island being Tahiti in the Society Islands group, which is also the most populous island and the seat of the capital of the territory...
uses UTC−10 for its major cities. The Cook Islands
Cook Islands
The Cook Islands is a self-governing parliamentary democracy in the South Pacific Ocean in free association with New Zealand...
and Tokelau
Tokelau
Tokelau is a territory of New Zealand in the South Pacific Ocean that consists of three tropical coral atolls with a combined land area of 10 km2 and a population of approximately 1,400...
do also. These areas do not use DST.