This week, a object will strech that indicate where it will seem to gleam farthest to a south of a equator, Â marking a impulse of a winter solstice â" a shortest day of 2011 in a Northern Hemisphere.
The occurs Thursday during 12:30 a.m. EST (0530 GMT), that corresponds to 9:30 p.m. PST on Wednesday for observers serve west. At a time, a object will be flitting over a over a Tropic of Capricorn.
Here's how northern winter solstice works: Since Jun 20, a altitude of a midday object has been obscure as a approach rays have been gradually migrating to a south. The sun's altitude above a setting during noontime is 47 degrees reduce now, compared to 6 months ago. As we mostly mention, your clenched fist reason during arm's length measures roughly 10 degrees, so a object during midday is now scarcely "five fists" reduce in a southern sky compared to Jun 21.
had no bargain of this transformation of a sun. They suspicion this astronomical machine competence mangle down someday, and a object would continue southward, never to return. As such, a obscure of a object was means for fear and wonder. []
As "armistice" is tangible as a staying of a movement of arms, "solstice" is a staying of a sun's apparent suit over a latitudes of a Earth. At a summer solstice, a object stops a northward suit and starts streamer south. At a winter solstice, it turns north.
Technically, during one notation past a impulse of a solstice, a object has incited around and started north. It will cranky a equator during a vernal equinox, flitting into a Northern Hemisphere on Mar 20, during 1:14 a.m. EDT (or on a calendar date of Mar 19 for those vital in a Mountain and Pacific Time Zones).Â
When a ancients saw a object stop and solemnly stand to a aloft midday location, people rejoiced; here was a guarantee that open would return. Most cultures had winter and some blending it to other events.Â
In Persia, a solstice noted a birthday of Mithra, a Sun King. In ancient times, Dec. 25 was a date of a intemperate Roman festival of Saturnalia, a arrange of bacchanalian thanksgiving. Saturnalia was distinguished around a time of a winter solstice. And in 275 A.D., a Roman Emperor, Aurelian, commemorated a feast day coinciding with a winter solstice: Die Natalis Invicti Solis ("The Birthday of a Unconquered Sun").Â
Among a many sundry etiquette related with this special deteriorate for thousands of years, a exchanging of gifts is roughly universal. Mother Nature herself offers a sky spectator in north ascetic latitudes a dual gifts of longest nights and a sky some-more pure than usual.
One reason for a clarity of a winter's night is that cold atmosphere can't reason as most dampness as comfortable atmosphere can. Hence, on many nights in a summer, a comfortable moisture-laden atmosphere causes a sky to seem hazier.
By day it is a milky, washed-out blue, that in winter becomes a richer, deeper and darker shade of blue. For observers in northern locations, this usually adds some-more dash to that partial of a sky containing a pleasing wintertime constellations.
Indeed, a that now accoutre a dusk sky, such as Sirius, Orion, Capella, Taurus and many others is clearly Nature's holiday emblem to commemorate a winter solstice and illuminate a prolonged cold nights of winter.
Joe Rao serves as an instructor and guest techer during New York's Hayden Planetarium. He writes about astronomy for The New York Times and other publications, and he is also an on-camera meteorologist for News 12 Westchester, New York.
News referensi http://news.yahoo.com/winter-solstice-brings-shortest-day-2011-week-172703536.html
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3:41 AM Friday, December 23, 2011