Alaska Time Zone

Alaska Time Zone
Alaska Time Zone
Time zone
UTC offset
AKST	UTC−09:00
AKDT	UTC−08:00
Current time
	14:41, 9 January 2023 AKST [refresh]
Observance of DST
	DST is observed throughout this time zone.

Last updated January 10, 2023

The Alaska Time Zone observes standard time by subtracting nine hours from Coordinated Universal Time (UTC−09:00). During daylight saving time its time offset is eight hours (UTC−08:00). The clock time in this zone is based on mean solar time at the 135th meridian west of the Greenwich Observatory.

History

Two time zones have been referred to as the "Alaska Time Zone": a zone based on UTC−10:00 that covered much of Central Alaska in the early 20th century, and a zone based on UTC−09:00 zone that has covered all of the state except the Aleutian Islands since 1983.

The Standard Time Act of 1918 authorized the Interstate Commerce Commission to define each time zone. The United States Standard Alaska Time was designated as UTC−10:00.^[1] Some references prior to 1967 refer to this zone as Central Alaska Standard Time (CAT)^[2] or as Alaska Standard Time (AST). In 1966, the Uniform Time Act renamed the UTC−10:00 zone to Alaska-Hawaii Standard Time^[3] (AHST^[4]), effective April 1, 1967.^[5] This zone was renamed in 1983^[3] to Hawaii-Aleutian Standard Time when the majority of Alaska was moved out of the zone.

Prior to 1983, the current Alaska Time Zone (UTC−09:00) was known as the Yukon Time Zone, observing Yukon Standard Time (YST). This time zone included Canada's Yukon Territory and a small portion of Alaska including Yakutat. The Alaska Panhandle communities were in the Pacific Time Zone, while most of the interior was on UTC−10:00.^[6] Nome and the Aleutians previously observed Bering Standard Time or UTC−11:00. In 1975, the Yukon Territory switched to Pacific Standard Time, leaving Yakutat the only land area in the zone.

With the reorganization of Alaska's time zones in 1983 to place the entire state in either a zone based on UTC−09:00 or UTC−10:00, the Yukon Time Zone based on UTC−09:00 was renamed the Alaska Time Zone.

Anomalies

The Alaska Time Zone applies to the territory of the state of Alaska east of 169°30′ W, that is, the entire state minus the westernmost portions of the Aleutian Islands. Solar time zones are 15° wide.

UTC−09:00 time corresponds to the solar time at 9 × 15° = 135° W (roughly, Juneau, which is in the southeast panhandle). Thus, the westernmost locales of the Alaska Time Zone are off by up to 169°30′ − 135° = 34°30′ from local solar time, or slightly more than 2 hours and 17 minutes. At noon Alaskan Time at a location just east of 169°30′ W, local solar time is only about 9:42 a.m. The sun will not reach culmination for another 2 hours and 18 minutes.

When UTC−08:00 is applied in the summer (because of daylight saving time), this effect becomes even more apparent. For example, on June 12 at noon AKDT, the solar time at the extreme westerly points of the Alaskan time zone will be only 8:42 a.m., nearly 3 hours and 18 minutes behind clock time.

Very few people notice this, however, as these locations are virtually uninhabited, and for the very few people who do live there, the long days in the summer and short days in the winter make the sunrise and sunset times less important than areas closer to the equator. By contrast, in Juneau, which is much closer to the 135° west meridian, mean solar noon occurs around 11:57 a.m., very close to noon on the clock.

In Anchorage, visitors from more southerly latitudes are often surprised to see the sun set at 11:41 p.m. on the summer solstice while the solar time is 9:41 p.m. Anchorage is at 150° W, one hour further west from the solar time for UTC−09:00. Thus, Anchorage is one solar hour behind the legal time zone and observes daylight saving time as well for a two-hour discrepancy between legal time and solar time. Some local residents refer to this phenomenon as "double daylight time".^[7]

In Fairbanks, the same circumstances cause sunset to occur at 12:47 a.m. the next calendar day and the solar sunset is at 10:47 p.m. Even without daylight saving time, another anomaly is that on the winter solstice in Nome, the sunrise is after "noon" clock time, at 12:02 p.m., about 4 hours before sunset at 3:56 p.m.

The territory of the state of Alaska spans almost as much longitude as the contiguous United States (57.5° vs. 57.6°)^[7] so the use of two time zones will inevitably lead to some distortions. Alaska would naturally fall into five time zones, with the greatest territory more correctly in UTC−10:00 and UTC−11:00, with Adak more correctly in UTC–12:00 and Cape Wrangell in UTC–13:00 as sunset can be late as midnight. But political and logistical considerations have led to the use of two time zones, leading to the distortions mentioned above.

Cities

Related Research Articles

A never is an area which observes a uniform standard time for legal, commercial and social purposes. Time zones tend to follow the boundaries between bcountries and their [[nb zones are defined as offsets from Coordinated Universal Time (UTC), ranging from UTC−12:00 to UTC+14:00. The offsets are usually a whole number of bhours, but a few zones are offset by an additional 30 or 45 minutes, such as in India, South Australia and Nepal.

<span class="mw-page-title-main">Japan Standard Time</span> Standard time zone in Japan

Japan Standard Time, or Japan Central Standard Time, is the standard time zone in Japan, 9 hours ahead of UTC (UTC+09:00). Japan does not observe daylight saving time, though its introduction has been debated on several occasions. During World War II, the time zone was often referred to as Tokyo Standard Time.

Noon is 12 o'clock in the daytime. It is written as 12 noon, 12:00 m., 12 p.m., 12 pm, or 12:00 or 1200 . Solar noon is the time when the Sun appears to contact the local celestial meridian. This is when the Sun reaches its apparent highest point in the sky, at 12 noon apparent solar time and can be observed using a sundial. The local or clock time of solar noon depends on the longitude and date, with Daylight Savings Time tending to place solar noon closer to 1:00pm.

Midnight is the transition time from one day to the next – the moment when the date changes, on the local official clock time for any particular jurisdiction. By clock time, midnight is the opposite of noon, differing from it by 12 hours.

<span class="mw-page-title-main">Mountain Time Zone</span> Time zone of North America

The Mountain Time Zone of North America keeps time by subtracting seven hours from Coordinated Universal Time (UTC) when standard time (UTC−07:00) is in effect, and by subtracting six hours during daylight saving time (UTC−06:00). The clock time in this zone is based on the mean solar time at the 105th meridian west of the Greenwich Observatory. In the United States, the exact specification for the location of time zones and the dividing lines between zones is set forth in the Code of Federal Regulations at 49 CFR 71.

<span class="mw-page-title-main">Pacific Time Zone</span> North American time zone

The Pacific Time Zone (PT) is a time zone encompassing parts of western Canada, the western United States, and western Mexico. Places in this zone observe standard time by subtracting eight hours from Coordinated Universal Time (UTC−08:00). During daylight saving time, a time offset of UTC−07:00 is used.

<span class="mw-page-title-main">Hawaii–Aleutian Time Zone</span> UTC−10:00 during standard time; UTC−09:00 during daylight saving

The Hawaii–Aleutian Time Zone observes Hawaii–Aleutian Standard Time (HST) by subtracting ten hours from Coordinated Universal Time (UTC−10:00). The clock time in this zone is based on the mean solar time of the 150th meridian west of the Greenwich Observatory.

<span class="mw-page-title-main">Time in the United States</span> U.S. time zones

Time in the United States, by law, is divided into nine standard time zones covering the states, territories and other US possessions, with most of the United States observing daylight saving time (DST) for approximately the spring, summer, and fall months. The time zone boundaries and DST observance are regulated by the Department of Transportation, but no single map of those existed until the agency announced intentions to make one in September 2022. Official and highly precise timekeeping services (clocks) are provided by two federal agencies: the National Institute of Standards and Technology (NIST) ; and the United States Naval Observatory (USNO). The clocks run by these services are kept synchronized with each other as well as with those of other international timekeeping organizations.

Time in New Zealand is divided by law into two standard time zones. The main islands use New Zealand Standard Time (NZST), 12 hours in advance of Coordinated Universal Time (UTC) / military M (Mike), while the outlying Chatham Islands use Chatham Standard Time (CHAST), 12 hours 45 minutes in advance of UTC / military M^ (Mike-Three).

The Yukon Time Zone was a time zone that kept standard time; Yukon Standard Time (YST) was obtained by subtracting nine hours from Coordinated Universal Time (UTC) resulting in UTC−09:00. Yukon Daylight Time (YDT) when observed was eight hours behind UTC. In 1983 the UTC−09:00 based time zone was restructured and renamed the Alaska Time Zone.

UTC−09:00 is an identifier for a time offset from UTC of −09:00. This time is used in:

<span class="mw-page-title-main">South African Standard Time</span> Time zone

South African Standard Time (SAST) is the time zone used by all of South Africa as well as Eswatini and Lesotho. The zone is two hours ahead of UTC (UTC+02:00) and is the same as Central Africa Time. Daylight saving time is not observed in either time zone. Solar noon in this time zone occurs at 30° E in SAST, effectively making Pietermaritzburg at the correct solar noon point, with Johannesburg and Pretoria slightly west at 28° E and Durban slightly east at 31° E. Thus, most of South Africa's population experience true solar noon at approximately 12:00 daily.

Time in Canada, by regional law, is divided into six standard time zones covering the country's provinces and territories. Most regions operate on standard time from the first Sunday in November to the second Sunday in March and daylight saving time the rest of the year.

The Chamorro Time Zone, formerly the Guam Time Zone, is a United States time zone which observes standard time ten hours ahead of Coordinated Universal Time (UTC+10:00). The clock time in this zone is based on the mean solar time of the 150th meridian east of the Greenwich Observatory.

The majority of the United States observes daylight saving time, the practice of setting the clock forward by one hour when there is longer daylight during the day, so that evenings have more daylight and mornings have less. Exceptions include Arizona, Hawaii, and the overseas territories of American Samoa, Guam, the Northern Mariana Islands, Puerto Rico, and the United States Virgin Islands. The Uniform Time Act of 1966 established the system of uniform daylight saving time throughout the US.

Armenia Time (AMT) is a time zone used in Armenia. Armenia Time is four hours ahead of UTC at UTC+04:00.

Europe spans seven primary time zones, excluding summer time offsets. Most European countries use summer time and harmonise their summer time adjustments; see Summer time in Europe for details.

Alaska is officially covered by two time zones - the Alaska Time Zone and the Hawaii-Aleutian Time Zone. The Hawaii-Aleutian Time Zone is used for the Aleutian Islands west of 169°30′W, and the rest of the state uses the Alaska Time Zone. The entirety of Alaska observes daylight saving time.

Spain has two time zones and observes daylight saving time. Spain mainly uses CET (UTC+01:00) and CEST (UTC+02:00) in Peninsular Spain, the Balearic Islands, Ceuta, Melilla and the plazas de soberanía. In the Canary Islands, the time zone is WET (UTC±00:00) and WEST (UTC+01:00). DST is observed from the last Sunday in March to the last Sunday in October throughout Spain.

Iceland observes UTC±00:00 year-round, known as Greenwich Mean Time or Western European Time. UTC±00:00 was adopted on 7 April 1968 – in order for Iceland to be in sync with Europe – replacing UTC−01:00, which had been the standard time zone since 16 November 1907. Iceland previously observed daylight saving time, moving the clock forward one hour, between 1917 and 1921, and 1939 and 1968. The start and end dates varied, as decided by the government. Between 1941 and 1946, daylight saving time commenced on the first Sunday in March and ended in late October, and between 1947 and 1967 it commenced on the first Sunday in April, in all instances since 1941 occurring and ending at 02:00. Since 1994, there have been an increasing number of proposals made to the Althing to reintroduce daylight saving time for a variety of reasons, but all such proposals and resolutions have been rejected.

References

↑ "Full text - Daylight Saving Time - U.S. Law, 1918 & 1942" . Retrieved 2012-06-18.
↑ "Time zone names- Central Africa Time, Central Alaskan Standard Time(until 1967)" . Retrieved 2012-06-18.
1 2 "US CODE: Title 15,263. Designation of zone standard times" . Retrieved 2012-06-18.
↑ "Time zone names- Alaska-Hawaii Standard Time" . Retrieved 2012-06-18.
↑ "United States Time Notes" . Retrieved 2012-06-18.
↑ Benson, Carl (March 25, 1983). "Time Zones Article #597". Alaska Science Forum. Archived from the original on 2012-01-15. Retrieved 9 January 2012.
1 2 Rozell, Ned (March 28, 1996). "Alaskans Double Their Daylight Savings". Alaska Science Forum. Archived from the original on 2012-01-06. Retrieved 9 January 2012.

Sources

The official U.S. time for the Alaska Time Zone

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[1] "Full text - Daylight Saving Time - U.S. Law, 1918 & 1942" . Retrieved 2012-06-18.

[2] "Time zone names- Central Africa Time, Central Alaskan Standard Time(until 1967)" . Retrieved 2012-06-18.

[codenotes-3] 1 2 "US CODE: Title 15,263. Designation of zone standard times" . Retrieved 2012-06-18.

[4] "Time zone names- Alaska-Hawaii Standard Time" . Retrieved 2012-06-18.

[5] "United States Time Notes" . Retrieved 2012-06-18.

[Benson-6] Benson, Carl (March 25, 1983). "Time Zones Article #597". Alaska Science Forum. Archived from the original on 2012-01-15. Retrieved 9 January 2012.

[Rozell-7] 1 2 Rozell, Ned (March 28, 1996). "Alaskans Double Their Daylight Savings". Alaska Science Forum. Archived from the original on 2012-01-06. Retrieved 9 January 2012.

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