Happy December (Winter) Solstice!

Happy Solstice Day! Once again, it's December 21st and this year at 4:22 PM PST, the North Pole will be tipped further away from the sun than at any other moment this year (approximately 23.5 degrees). Today, the northern hemisphere will experience its shortest period of daylight and it's longest period of night - it's the middle of winter. Simultaneously, it's the middle of summer in the southern hemisphere and people there are enjoying the longest day and shortest night of the year today.

If you're standing on the Tropic Of Capricorn, the sun will appear directly overhead at noon today. This is the only day of the year on which that is true. And if you're standing on the Antarctic Circle, today you will *finally* see the sun all day long. At the South Pole, the sun has been up for three months (since the September Equinox), but today it will be at it's highest point in the sky this year (again, 23.5 degrees). At the North Pole, you're in the middle of a very long period of darkness. The sun hasn't risen above the horizon since the september equinox and it won't rise again for another three months - at the March Equinox.

Today is often called the "Winter Solstice", but this is true only in the northern hemisphere. Astronomers (and others wishing to maintain a "world view" of things, I suppose) now refer to all the solstices and equinoxes by the month in which they occur.