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international date line
international date line imaginary line on the earth's surface, generally following the 180° meridian of longitude , 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 time ), 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. |
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"international date line." The Columbia Encyclopedia, 6th ed.. 2011. Encyclopedia.com. 28 May. 2012 <http://www.encyclopedia.com>. "international date line." The Columbia Encyclopedia, 6th ed.. 2011. Encyclopedia.com. (May 28, 2012). http://www.encyclopedia.com/doc/1E1-intldate.html "international date line." The Columbia Encyclopedia, 6th ed.. 2011. Retrieved May 28, 2012 from Encyclopedia.com: http://www.encyclopedia.com/doc/1E1-intldate.html |
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International Date Line
International Date Line, a line running mainly along the longitude of 180° but with adjustments to avoid the division of certain Island groups which lie astride it, the Aleutian Islands in the north and the Fiji, Tonga, and Kermadoc groups, with New Zealand, in the south. It is on this international dateline that the zone times of +12 hours and -12 hours meet and the date changes. If a traveller round the world sets out from Greenwich (see greenwich mean time), on 0° longitude, and travels eastwards, he puts his clock forward by one hour as he crosses each 15° of longitude, so that by the time he reaches Greenwich again, his clock has been put forward by 24 hours and he is one day ahead in date. To correct this anomaly, he subtracts a day when he crosses the international dateline eastwards and adds a day when he crosses it westwards. So in the former case the same calendar date is used for two successive periods of 24 hours; in the latter case one calendar date is omitted altogether.
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"International Date Line." The Oxford Companion to Ships and the Sea. 2006. Encyclopedia.com. 28 May. 2012 <http://www.encyclopedia.com>. "International Date Line." The Oxford Companion to Ships and the Sea. 2006. Encyclopedia.com. (May 28, 2012). http://www.encyclopedia.com/doc/1O225-InternationalDateLine.html "International Date Line." The Oxford Companion to Ships and the Sea. 2006. Retrieved May 28, 2012 from Encyclopedia.com: http://www.encyclopedia.com/doc/1O225-InternationalDateLine.html |
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International Date Line
International Date Line The imaginary line on the Earth's surface stretching from pole to pole through the Pacific Ocean which, by international agreement in 1884, marks the beginning or ending of a day. The line approximately follows the meridian of longitude 180°, bending where necessary to avoid cutting through land. To the east of the line, the date is one day behind the west of the line. On crossing this line in a westerly direction the calendar must be put forward one day, while if it is crossed in an easterly direction the calendar is put one day back.
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Cite this article
"International Date Line." A Dictionary of Astronomy. 1997. Encyclopedia.com. 28 May. 2012 <http://www.encyclopedia.com>. "International Date Line." A Dictionary of Astronomy. 1997. Encyclopedia.com. (May 28, 2012). http://www.encyclopedia.com/doc/1O80-InternationalDateLine.html "International Date Line." A Dictionary of Astronomy. 1997. Retrieved May 28, 2012 from Encyclopedia.com: http://www.encyclopedia.com/doc/1O80-InternationalDateLine.html |
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international date line
international date line an imaginary north-south line through the Pacific Ocean, adopted in 1884, to the east of which the date is a day earlier than it is to the west. It lies chiefly along longitude 180°, with diversions to pass around some island groups.
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"international date line." The Oxford Essential Dictionary of the U.S. Military. 2001. Encyclopedia.com. 28 May. 2012 <http://www.encyclopedia.com>. "international date line." The Oxford Essential Dictionary of the U.S. Military. 2001. Encyclopedia.com. (May 28, 2012). http://www.encyclopedia.com/doc/1O63-internationaldateline.html "international date line." The Oxford Essential Dictionary of the U.S. Military. 2001. Retrieved May 28, 2012 from Encyclopedia.com: http://www.encyclopedia.com/doc/1O63-internationaldateline.html |
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International Date Line
In·ter·na·tion·al Date Line • n. see Date Line. |
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Cite this article
"International Date Line." The Oxford Pocket Dictionary of Current English. 2009. Encyclopedia.com. 28 May. 2012 <http://www.encyclopedia.com>. "International Date Line." The Oxford Pocket Dictionary of Current English. 2009. Encyclopedia.com. (May 28, 2012). http://www.encyclopedia.com/doc/1O999-internationaldateline.html "International Date Line." The Oxford Pocket Dictionary of Current English. 2009. Retrieved May 28, 2012 from Encyclopedia.com: http://www.encyclopedia.com/doc/1O999-internationaldateline.html |
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international date line
international date line see international date line . |
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Cite this article
"international date line." The Columbia Encyclopedia, 6th ed.. 2011. Encyclopedia.com. 28 May. 2012 <http://www.encyclopedia.com>. "international date line." The Columbia Encyclopedia, 6th ed.. 2011. Encyclopedia.com. (May 28, 2012). http://www.encyclopedia.com/doc/1E1-X-dateline.html "international date line." The Columbia Encyclopedia, 6th ed.. 2011. Retrieved May 28, 2012 from Encyclopedia.com: http://www.encyclopedia.com/doc/1E1-X-dateline.html |
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