Monday, December 20, 2004

The longest night 

Tonight is crisp, cold and clear in Seattle. The half-full moon and city-bright stars are out, and Orion's belt is pointing toward the roof of our house.

I've been waiting for this night for three months. It's the longest night of the year, and here that means more than in any other place I've lived. While I have spent colder December nights in Boston, and wetter ones in Houston, this is the farthest north I have lived, so this night is the longest that I have known.

According to a Seattle Times article today, this longest night is special:
Tonight will be the longest night of the year: 15 hours and 36 minutes. It also will be the longest night for thousands of years to come.

Each year, the Earth tilts a bit less on its axis relative to the sun, gradually shortening both winter's longest night and summer's longest day. We're now at about 23.5 degrees away from perpendicular. Ten thousand years from now, the Earth's tilt will be about 22 degrees. Then the angle will start to grow again.

Not that this is something that I'm ever going to notice, but it's nice to know that this is the darkest that it's going to get in my lifetime.