- published: 31 Oct 2013
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Alaska (i/əˈlæskə/) 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. Alaska is the 4th least populous and the least densely populated of the 50 United States. Approximately half of Alaska's 722,718 residents live within the Anchorage metropolitan area.
Alaska was purchased from Russia on March 30, 1867, for $7.2 million ($120 million in today's[when?] dollars) at approximately two cents per acre ($4.74/km²). The land went through several administrative changes before becoming an organized (or incorporated) territory on May 11, 1912, and the 49th state of the U.S. on January 3, 1959.
The name "Alaska" (Аляска) was already introduced in the Russian colonial period, when it was used only for the peninsula and is derived from the Aleut alaxsxaq, meaning "the mainland" or, more literally, "the object towards which the action of the sea is directed". It is also known as Alyeska, the "great land", an Aleut word derived from the same root.
A time zone is a region on Earth that has a uniform standard time for legal, commercial, and social purposes. It is convenient for areas in close commercial or other communication to keep the same time, so time zones tend to follow the boundaries of countries and their subdivisions.
Most of the 40 time zones on land are offset from Coordinated Universal Time (UTC) by a whole number of hours (UTC−12 to UTC+14), but a few are offset by 30 or 45 minutes. Some higher latitude countries use daylight saving time for part of the year, typically by changing clocks by an hour. Many land time zones are skewed toward the west of the corresponding nautical time zones. This also creates a permanent daylight saving time effect.
Before the invention of clocks, people marked the time of day with apparent solar time (or "true" solar time) – for example, the time on a sundial – which was typically different for every settlement.
When well-regulated mechanical clocks became widespread in the early 19th century,[citation needed] each city began to use some local mean solar time. Apparent and mean solar time can differ by up to around 15 minutes (as described by the equation of time) due to the non-circular shape of the Earth's orbit around the sun. Mean solar time has days of equal length, and the difference between the two averages to zero after a year.