Wednesday, May 6, 2009


#9 On what day of the year are shadows the shortest where you live?

The June solstice, usually on June 21st in the Western hemisphere, is the day when shadows are shortest here in Phoenix, but this can vary slightly depending on the calendar year. If we lived in the Southern hemisphere, we would observe the shortest shadows on the December solstice, December 21st. As the sun rises higher in the sky and the days become longer, and warmer (the forecast for Phoenix is 104 F on Friday this week!), the shadows become shorter. A good shade tree is a blessing.

The path of the sun, or ecliptic, is the basis for many ceremonial observances in all cultures. June weddings (in Euro-centric cultures like ours) were originally celebrated around the solstice, symbolic of ancient pagan observances of this celestial event as the marriage of the God and Goddess, or Heaven and Earth, a union that creates the fruits of harvest. I wonder if December is a popular time for weddings in South America and South Africa for similar reasons?

One of my favorite exhibits about the ecliptic, besides the cool archaeological monuments like Stone Henge and some rock art in the southwest, is a contemporary design at the North Mountain Visitor Center in Phoenix. Although I've been aware of the ecliptic and observed the equinox and solstice dates for decades, this exhibit really enlightened my understanding of the dramatic variation in where the sun rises and sets over the year. Seeing this on paper is not the same as standing in the middle of the exhibit and feeling it.

Another fun exhibit or artwork on this theme is a human sun dial at Life Lab near the UCSC campus in Santa Cruz, California. When you stand in the middle of the circle, your shadow points to the solar time of day. I've got some ideas to create a pebble mosaic like this when I have a big enough yard to accommodate one.

Archaeoastronomy, or "the study of how people have understood the phenomena in the sky, how they used phenomena in the sky and what role the sky played in their cultures" is fascinating to me. I wonder how our modern urban cultural myths might change, or have been changed, as we've become less and less tuned to the sun, moon and stars in our daily (or nightly) lives And how would it feel if we returned to judging the time of day by the length and direction of our shadows, rather than using a clock?

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