Naturalist's Almanac

The winter solstice occurs around December 21-22 every year and confronts me with a night that lasts so long that some primitive part of my brain wonders if the sun is ever going to rise again. At this time of year I walk up and down my road, looking at the sun from various angles and at different times of day, trying to understand textbook explanations of what’s happening.

The best I can do is envision a simplified solar system with the sun a big ball at the center and the Earth a smaller ball orbiting around it. If I freeze-frame this simplified solar system, drive a rod through the center of the Earth, and tilt the rod away from the sun, I see exactly what happens at the winter solstice: the tilted Earth’s Northern Hemisphere points as far away from the sun as it’s going to point all year.

But why are the days so dark and the nights so long? The textbooks invite me to imagine a flat horizon with clear views both east and west. They show the sun rising later and farther south every morning, traveling lower across the daytime sky, and setting earlier at the end of a shorter arc. No wonder that primitive part of my brain worries that it’s going to disappear altogether.

Recently, one of my elderly farm neighbors, who was sitting quietly at his kitchen window watching the sun itself while I was pacing up and down the road, gave me a special gift. He loved to watch the sun come up every morning and decided to draw an extended picture of how the sunrise moves along the horizon he could see from where he sat.

Because this horizon includes a distinctive mountain called Camel’s Hump, his drawing shows clearly what the sun does between the summer and winter solstices. It rises well to the left of Camel’s Hump on June 20 and well to the right on December 21. If he had also included how high the sun travels above the horizon, it would show exactly what my textbook graphics with all their intersecting planes and arcs were trying to explain.

I am grateful to have a copy of my neighbor’s “horizon calendar,” which he gave me shortly before he died. I framed it and keep it on the wall above my desk to remind me that despite my continuing efforts to understand the whole solar system, my daily life takes place right here on Earth. My own horizon, if I attend to it, will teach me what’s important about the sun — that it will indeed rise again after the longest night, reverse direction, and start its six-month journey back toward the longest day.

MORE INFORMATION

Windows to the Universe
http://www.windows.ucar.edu/tour/link=/the_universe/uts/winter.html

This Web site offers about as clear an explanation of the winter solstice as I’ve found. It includes colorful graphics to illustrate the concepts I wrestle with whenever I try to think about the Earth as a planet rotating on a a tilted axis and traveling in an elliptical orbit around the sun.

U.S. Naval Observatory
http://aa.usno.navy.mil/data/docs/EarthSeasons.html

If all you want to know is the date and time of the winter solstice, this link will take you to the U.S. Naval Observatory’s list for 1992-2005.

Horizon Calendar
http://www.clarkfoundation.org/astro-utah/vondel/suncalendar.html

This link takes you to a newspaper column written by an astronomer who happens to be the retired director of the Hansen Planetarium in Salt Lake City. This particular column talks about creating a horizon calendar like my neighbor's.

Winter Solstice Celebrations
http://www.clarkfoundation.org/astro-utah/vondel/solsticewin.html

In this column the same astronomer talks about how various cultures have observed or celebrated the winter solstice over the centuries. He mentions the Zoroastrians, Zuni, Hopi, Romans, and Christians.

Festivals of Light
http://www.clarkfoundation.org/astro-utah/vondel/FestivalsOfLight.html

In yet another column this same very interesting astronomer discusses why we turn on so many lights during December and why we have chosen to make the transition from one year to the next at this particular time of year.