Alaska Time Zone

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Alaska Time Zone
Time zone
Timezoneswest.PNG
UTC offset
AKST UTC−09:00
AKDT UTC−08:00
Current time
07:23, 19 February 2024 AKST [refresh]
Observance of DST
DST is observed throughout this time zone.

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.

Contents

The zone includes nearly all of the U.S. state of Alaska and is one hour behind the Pacific Time Zone.

The western Aleutian Islands observe Hawaii–Aleutian Time, one hour behind the remainder of the state.

The largest city in the Alaskan Time Zone is Anchorage, Alaska. The Anchorage Metropolitan Area is the largest metropolitan area in the zone.

Effective from 2007, the local time changes from AKST to AKDT at 02:00 LST (local standard time) to 03:00 LDT (local daylight time) on the second Sunday in March and returns at 02:00 LDT to 01:00 LST on the first Sunday in November. As such, Alaska spends most of the year on daylight saving time rather than standard time.

History

Period in useTime offset from UTCName of time
Wednesday, July 15, 1741 – Friday, October 6, 1867 (Julian Calendar)UTC+14:59 (in Sitka) Local Mean Time
UTC+12:24 (in Aleutian Islands)
Friday, October 18, 1867 – 1900 (Gregorian Calendar)UTC−09:01 (in Sitka)Local Mean Time
UTC−11:36 (in Aleutian Islands)
1900 – 1918 UTC−09:00 (including Aleutian Islands)Alaska Standard Time
1918 – January 19, 1942 UTC−08:00 (Panhandle Areas) Pacific Standard Time
UTC−09:00 (in Yakutat)Yukon Standard Time
UTC−10:00 Alaska Standard Time
UTC−11:00 (Nome, and Aleutian Islands)Bering Standard Time
January 20, 1942 – September 30, 1945 UTC−07:00 (Panhandle Areas)Pacific War Time
UTC−08:00 (in Yakutat)Yukon War Time
UTC−09:00Alaska War Time
UTC−10:00 (Nome, and Aleutian Islands)Bering War Time
September 30, 1945 – March 31, 1967UTC−08:00 (Panhandle Areas) Pacific Standard Time
UTC−09:00 (in Yakutat)Yukon Standard Time
UTC−10:00Alaska Standard Time
UTC−11:00 (Nome, and Aleutian Islands)Bering Standard Time
April 1, 1967 – 1983UTC−08:00 (Panhandle Areas)Pacific Standard Time
UTC−09:00 (in Yakutat)Yukon Standard Time
UTC−10:00Alaska–Hawaii Standard Time
UTC−11:00 (Nome, and Aleutian Islands)Bering Standard Time
1983 – PresentUTC−09:00 (in Juneau)Alaska Time Zone
UTC−10:00 (in Aleutian Islands) Hawaii-Aleutian Time Zone
2007 − PresentUTC−08:00 (except in Aleutian Islands)Alaska Daylight Time

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 consolidation of Alaska's four time zones into two in 1983, [7] the entire state was in either a zone based on UTC−09:00 or UTC−10:00.[ citation needed ] The Yukon Time Zone based on UTC−09:00 was later renamed the Alaska Time Zone in 1984. [7] [8]

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". [9]

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°) [9] so the use of only 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

See also

Related Research Articles

<span class="mw-page-title-main">Time zone</span> Area that observes a uniform standard time

A time zone is an area which observes a uniform standard time for legal, commercial and social purposes. Time zones tend to follow the boundaries between countries and their subdivisions instead of strictly following longitude, because it is convenient for areas in frequent communication to keep the same time.

<span class="mw-page-title-main">Noon</span> 12 oclock in the daytime

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 date, longitude, and time zone, with Daylight Saving Time tending to place solar noon closer to 1:00pm.

<span class="mw-page-title-main">Midnight</span> Transition time from one day to the next

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">Midnight sun</span> Natural phenomenon when daylight lasts for a whole day

Midnight sun is a natural phenomenon that occurs in the summer months in places north of the Arctic Circle or south of the Antarctic Circle, when the Sun remains visible at the local midnight. When midnight sun is seen in the Arctic, the Sun appears to move from left to right. In Antarctica, the equivalent apparent motion is from right to left. This occurs at latitudes from 65°44' to 90° north or south, and does not stop exactly at the Arctic Circle or the Antarctic Circle, due to refraction.

<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

In the United States, time is divided into nine standard time zones covering the states, territories and other US possessions, with most of the country 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).

In modern usage, civil time refers to statutory time as designated by civilian authorities. Modern civil time is generally national standard time in a time zone at a fixed offset from Coordinated Universal Time (UTC), possibly adjusted by daylight saving time during part of the year. UTC is calculated by reference to atomic clocks and was adopted in 1972. Older systems use telescope observations.

The Yukon Time Zone was a formerly observed 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 it was renamed the Alaska Time Zone in 1984. Yukon currently observes Mountain Time Zone and does not observe daylight-saving time.

<span class="mw-page-title-main">UTC−09:00</span> 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.

<span class="mw-page-title-main">Time in Canada</span> Time zones of Canada

Canada is divided into six time zones. Most areas of the country's provinces and territories 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.

<span class="mw-page-title-main">Chamorro Time Zone</span> Time zone for Guam and Northern Mariana Islands

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.

<span class="mw-page-title-main">Daylight saving time in the United States</span> Practice of setting the clock forward by one hour in the United states

Most 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.

<span class="mw-page-title-main">Time in Europe</span> Time zones in Europe

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.

Hawaii is in the Hawaii–Aleutian Time Zone and does not observe daylight saving time.

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.

<span class="mw-page-title-main">Time in Spain</span> Time zones in Spain

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, 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.

<span class="mw-page-title-main">Time in Iceland</span>

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

  1. "Full text - Daylight Saving Time - U.S. Law, 1918 & 1942" . Retrieved June 18, 2012.
  2. "Time zone names- Central Africa Time, Central Alaskan Standard Time(until 1967)" . Retrieved June 18, 2012.
  3. 1 2 "US CODE: Title 15,263. Designation of zone standard times" . Retrieved June 18, 2012.
  4. "Time zone names- Alaska-Hawaii Standard Time" . Retrieved June 18, 2012.
  5. "United States Time Notes" . Retrieved June 18, 2012.
  6. Benson, Carl (March 25, 1983). "Time Zones Article #597". Alaska Science Forum. Archived from the original on January 15, 2012. Retrieved January 9, 2012.
  7. 1 2 Turner, Wallace (November 1, 1983). "Alaska's Four Time Zones Now Two". The New York Times . p. A25. Retrieved June 28, 2023.
  8. Supplemental Appropriations Act, 1984. Section 2003. 97  Stat.   1153
  9. 1 2 Rozell, Ned (March 28, 1996). "Alaskans Double Their Daylight Savings". Alaska Science Forum. Archived from the original on January 6, 2012. Retrieved January 9, 2012.

Sources