Naturalist's Almanac

Around June 20-21 every year we reach the point in the solar year called the summer solstice. Astronomy books explain the exact positions of the sun and Earth at that moment, but even with good graphics I find myself on overload. To understand what happens at the solstice I need to watch the sun itself.

I'm lucky enough to live near a mountain called Camel's Hump that gives me a clear point of reference on my local horizon. The mountain is to the east of me, so I can watch the sun rise behind it. On the days leading up to the June 20s, the sun rises farther and farther to the left of the mountain. But then, at the time of the solstice, it stops and starts moving back to the right.

Even if you don't have a mountain on your eastern horizon, you can simulate what I see with a TV table, a glass, and a round pizza pan. Put the glass upside down on the far side of the TV table to be the "mountain".

Kneel down, reach under the TV table, and hold the pizza pan behind the glass like a backdrop. Lower it until you have just a small arc showing above the far edge of the table. Its intersections with the table are the points at which the sun rises and sets halfway around the year at the winter solstice.

Now raise the pizza pan slowly, watching what happens to the points of sunrise and sunset with respect to the mountain. When you've raised the pizza pan far enough to see the leftward movement of the sunrise and the rightward movement of the sunset, stop. You're now ready to conceptualize the summer solstice.

The word solstice which derives from Latin words for "sun" and "stands still" refers to the time when the sunrise and sunset seem to stop before changing directions. We experience this brief "standing still" as our longest day and shortest night. Now start lowering the pizza pan toward its original position to see what happens after the summer solstice.

Our primitive ancestors didn't have to use pizza pans to observe what the sun did with respect to their local horizon. Maybe they couldn't calculate the summer solstice to the exact minute as astronomers can today, but they could certainly respond to the expansion and contraction of daylight on either side of it.

Before calendars and clocks came along to distract us, the most attentive and observant of our wise elders probably knew exactly when the sun was going to stand still.

MORE INFORMATION

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

The only thing unfriendly about this Web site is its address. The information is clear, easy-to-read, and linked to definitions of words that might need some explaining. The text is offered in Beginner, Intermediate, and Advanced versions, with colorful graphics to illustrate exactly what the sun and Earth are doing at the summer solstice.

Astro-Utah
http://www.clarkfoundation.org/astro-utah/vondel/solsticesum.html

This link takes you to a popular interest newspaper column written by the retired director of the Hansen Planetarium in Salt Lake City. He talks about summer solstices now and in the past, mentioning New Age, Druid, and Native American celebrations. As an astronomer, he himself celebrates how much we have learned about the Earth and the sun and offers links to other Web sites that offer good scientific information on the solstice and other subjects.

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 summer solstice, this link will take you to the U.S. Naval Observatory’s list.