You may have noticed that it has been a little chilly lately. Winter has arrived. The first day of winter in the northerm hemisphere, the winter solstice, is Tuesday December 21, 2010. This solstice also marks the first day of summer in the southern hemisphere.
The instant of the winter solstice is 6:38 PM Eastern standard time. At this time, the Sun will be overhead on the Tropic of Capricorn at a latitude of 23.5 degrees south. The winter solstice also marks the time when the Sun appears furthest south as seen from Earth.
In an unusual coincidence the 2010 winter solstice is on the same day as a total lunar eclipse. This eclipse of the Moon will be visible from North America, the Pacific, and eastern Asia. The eclipse will occur before dawn on the morning of December 21. In more western locations it will start on the night of Monday December 20.
As Earth continues its orbit around the Sun, the Sun will appear to move northward in the sky. This apparent north-south motion of the Sun in the sky causes the seasons. Contrary to popular belief, the seasons are not in any way caused by the changing distance between Earth and the Sun. In fact Earth is at its closest point to the Sun on January 3, 2011.
Break out your warm clothes for the first day of winter and enjoy a total lunar eclipse on the winter solstice.
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