international date line


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Related to international date line: Time zones

date line, international:

see international date lineinternational date line,
imaginary line on the earth's surface, generally following the 180° meridian of longitude, where, by international agreement, travelers change dates.
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international date line,

imaginary line on the earth's surface, generally following the 180° meridian of longitudelongitude
, angular distance on the earth's surface measured along any latitude line such as the equator east or west of the prime meridian. A meridian of longitude is an imaginary line on the earth's surface from pole to pole; two opposite meridians form a great circle dividing
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, where, by international agreement, travelers change dates. Traveling eastward across the line, one subtracts one calendar day; traveling westward, one adds a day. The date line is necessary to avoid a confusion that would otherwise result. For example, if an airplane were to travel westward with the sun, 24 hr would elapse as it circled the globe, but it would still be the same day for those in the airplane while it would be one day later for those on the ground below them. The same problem would arise if two travelers journeyed in opposite directions to a point on the opposite side of the earth, 180° of longitude distant. The eastward traveler would set his clock ahead 1 hr for each 15° of longitude (see standard timestandard time,
civil time used within a given time zone. The earth is divided into 24 time zones, each of which is about 15° of longitude wide and corresponds to one hour of time. Within a zone all civil clocks are set to the same local solar time.
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), so that his clock would gain a total of 12 hr; the westward traveler would set his clock back 1 hr for each 15°, resulting in a total loss of 12 hr. The two clocks would therefore differ by 24 hr, or one calendar day. The apparent paradox is resolved by requiring that the traveler crossing the date line change his date, thus bringing the travelers into agreement when they meet. The international date line does not follow the 180° meridian along its entire course but bends eastward around the eastern tip of Siberia, westward around the Aleutian Islands, and eastward again around various island groups in the South Pacific (mostly extremely around Kiribati) to avoid a date change within island nations and territories or between important trade partners.

international date line

[¦in·tər¦nash·ən·əl ′dāt ‚līn]
(astronomy)
A jagged arbitrary line, roughly equal to the 180° meridian, where a date change occurs: if the line is crossed from east to west a day is skipped, if from west to east the same day is repeated.

international date line

international date line
The Greenwich antimeridian, or 180° longitude. The international date line, however, does not follow the Greenwich antimeridian exactly but is distorted to place inhabited areas definitely on one side or the other of the line to avoid a difference in date in an inhabited area. Also called a calendar line or a date line.

International Date Line

the line approximately following the 180? meridian from Greenwich on the east side of which the date is one day earlier than on the west
References in periodicals archive ?
Several nations tout their proximity to the International Date Line in their tourism promotions.
and others to the east of the International Date Line.
AO: Covers 48 million square miles of the Pacific and Indian Oceans, from the International Date Line to the waters east of Africa, and from the Kuril Islands in the north to the Antarctic in the south, including 39 coastal nations.
The first crossing of the International Date Line by kiteboard.
territories and lies on the other side of the International Date Line.
New Zealand is one of the first countries to see in the new day, as it is situated at the eastern most part of the International Date Line, midnight in Auckland occurring at 1100 GMT.
The sea-surface warming characteristic of El Nino typically stretches along the equator from the coast of South America to the international date line, with the largest temperature anomalies in the eastern Pacific.
The trip spanned 28 days, with a jump across the International Date Line.
Another giving me an C[pounds sterling]extraC[yen] day for the one I lost, when I flew across the International Date Line.
Tim Cahill, however, had no hesitation of suffering jetlag and flying across the international date line when the chance to link up with his team-mates came about - never mind that he can't yet kick a football - but being among familiar faces is a tonic in itself.
He describes the history of the international technical accords on the International Date Line, the system of standard time zones around the globe, and Daylight Saving Time, all of which are linked to international acceptance of Greenwich as the prime meridian.
The trip to Tokelau involved a stop in Samoa, which sits on the edge of the International Date Line.

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