Winter Solstice Brings Shortest Day of 2011 This Week

by Joe Rao, SPACE.com Skywatching Columnist

Date: 21 December 2011 Time: 12:00 PM ET

The solstice will occur Thursday, Dec. 22, 2011. On this day, the sun is at its farthest southern declination, and is 6.5 degrees away from the center of the Milky Way.
CREDIT: Starry Night Software

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This week, the sun will reach that point where it will appear to shine farthest to the south of the equator, marking the moment of the winter solstice — the shortest day of 2011 in the Northern Hemisphere.
The winter solstice occurs Thursday at 12:30 a.m. EST (0530 GMT), which corresponds to 9:30 p.m. PST on Wednesday for observers further west. At the time, the sun will be passing over the over the Tropic of Capricorn.
Here's how northern winter solstice works: Since June 20, the altitude of the midday sun has been lowering as its direct rays have been gradually migrating to the south. The sun's altitude above the horizon at noontime is 47 degrees lower now, compared to six months ago. As we often mention, your clenched fist held at arm's length measures roughly 10 degrees, so the sun at midday is now nearly "five fists" lower in the southern sky compared to June 21.

MORE: http://www.space.com/14010-winter-solstice-2011-shortest-day-explained.html

Why the Winter Solstice Arrives This Week

Wynne Parry, LiveScience Senior Writer

Date: 21 December 2011 Time: 08:07 AM ET

The winter solstice marks the shortest day of the year, when the sun is at its lowest point in the sky.
CREDIT: Stockxpert.

Winter officially arrives late Wednesday or in the wee hours of Thursday, depending on the time zone you are in.
The official time corresponds to 12:30 a.m. EST (9:30 p.m. PST, or 5:30 a.m. Universal Time) Thursday (Dec. 22). This is the point when the northern half of our planet will face directly away from the sun.
This means that days, which have up until now been growing shorter in the Northern Hemisphere, will begin to lengthen.
This happens because the Earth rotates on an axis that is tilted by 23.5 degrees, so the planet leans one way or another as it travels around the sun. This doesn't make much difference for folks living around the Earth's equator, but for those of us farther north, or south, this tilt creates seasons.

MORE: http://www.livescience.com/17575-winter-solstice-science-2011.html

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