Winter Officially Begins December 21:
The winter solstice will occur at 538pm CST on December 21, 2010. The winter solstice marks the shortest day and longest night of the year. The winter solstice marks the beginning of winter in the Northern Hemisphere and summer in the Southern Hemisphere. In the Northern Hemisphere, it occurs when the sun is directly over the Tropic of Capricorn, which is located at 23.5° south of the equator and runs through Australia, Chile, southern Brazil, and northern South Africa.
We all know that the Earth makes a complete revolution around the sun once every 365 days, following an orbit that is elliptical in shape. This means that the distance between the Earth and Sun, which is 93 million miles on average, varies throughout the year. During the first week in January, the Earth is about 1.6 million miles closer to the sun. This is referred to as the perihelion. The aphelion, or the point at which the Earth is about 1.6 million miles farther away from the sun, occurs during the first week in July. This fact may sound counter to what we know about seasons in the Northern Hemisphere, but actually the difference is not significant in terms of climate and is NOT the reason why we have seasons. Seasons are caused by the fact that the Earth is tilted on its axis by 23.5°. The tilt's orientation with respect to space does not change during the year; thus, the Northen Hemisphere is tilted toward the sun in June and away from the sun in December, as illustrated in the graphic below.
The winter solstice occurs annually on a day between December 20 and December 23. Its date varies from December 20 to December 23 depending on the year in the Gregorian calendar. December 20 and December 23 solstices occur less frequently than December 21 or December 22 solstices. The last December 23 solstice occurred in 1903 and will not occur again until 2303. A December 20 solstice has occurred very rarely, with the next one not occurring until the year 2080.
On this date, all locations above a latitude of 66.5 degrees north are now in darkness, while locations below a latitude of 66.5 degrees south will be in 24 hours of daylight. The sun is directly overhead on the Tropic of Capricorn in the southern hemisphere during the winter solstice. People living south of the Tropic of Capricorn will experience the longest day of the year in terms of daylight hours. Those living or travelling south from the Antarctic Circle towards the South Pole will experience the "midnight sun" during this time of the year.
However, for people living in the northern hemisphere, the winter solstice is the day of the year with the least hours of daylight for those living north of the Tropic of Cancer. Those living north of the Arctic Circle towards the North Pole will not see the sun during this time of the year.
Sunrise/Sunset times for various locations in our area on December 21, 2010
PADUCAH, KY = SUNRISE: 704am CST SUNSET: 441pm CST
HOPKINSVILLE, KY = SUNRISE: 659am CST SUNSET: 437pm CST
OWENSBORO, KY = SUNRISE: 700am CST SUNSET: 433pm CST
MADISONVILLE, KY = SUNRISE: 700am CST SUNSET: 436pm CST
HENDERSON, KY = SUNRISE: 702am CST SUNSET: 435pm CST
CAPE GIRARDEAU, MO = SUNRISE: 709am CST SUNSET: 444pm CST
POPLAR BLUFF, MO = SUNRISE: 710am CST SUNSET: 449pm CST
SIKESTON, MO = SUNRISE: 708am CST SUNSET: 445pm CST
EVANSVILLE, IN = SUNRISE: 703am CST SUNSET: 434pm CST
CARBONDALE, IL = SUNRISE: 708am CST SUNSET: 442pm CST
For complete sunrise/sunset data for other locations, click here