Wednesday, July 29, 2009

The Science and Art of the Sundial

The sundial incorporates science in that its specific design and alignment will mark the passage of time; it embraces art in that its minimalistic components create a simple beauty.

And so it is with the Sundial Bridge at Turtle Bay in Redding, CA. This view shows the planters that prevent any kind of four-wheel vehicle from entering the bridge. At the far end of the bridge, a tower appears to rise. However, it is an angled cantilever tower loaded by cables on only one side (photos below).

The Sundial Bridge is 700 feet in length and crosses the Sacramento River without touching the water.

The cables are not centered on the walkway but instead divide the bridge into a major and minor path.

Traffic on the bridge was relatively light at about 8:30 in the morning, so there was plenty of space for the jogging father and cycling son.

The bridge's deck is surfaced with translucent structural glass, which is illuminated from beneath and glows aquamarine at night.

When viewing the bridge from the north end, the sundial emerges. The mast (or gnomon, right) is 207 feet long. When setting up a sundial, you must also align it correctly with the Earth's axis for it to tell accurate time. Since the Sundial Bridge at Turtle Bay is a bridge that was made to span a narrow portion of the Sacramento River, it could not be aligned at the correct degrees.

Because of this, and because the angle of the style must be exactly equal to the latitude for which the dial is designed, there is only one day a year when the Sundial Bridge at Turtle Bay accuratley tells time--June 21, Summer Solstice.

The artistic beauty of the Sundial Bridge is most apparent at its north end. Here the curves of the bridge play against the blue sky to create a sense of motion to compliment the movement of the sundial's shadow.

The bridge was designed by Spanish architect and engineer Santiago Calatrava and completed in 2004 at a cost of $23,000,000.

We could have stayed longer and found more interesting viewpoints, but the temperature was already well on its way to the low 100s.

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