Saturday, June 22, 2013

Summer Solstice at Miantonomi's Cave

Last year, I missed the summer solstice patterns inside Miantonomi's  Cave because the show finishes an hour before sunset.  This year I arrived early.
    Summer solstice is the only time the face of the slanted boulder is illuminated by sunlight. The 318 degree bearing of the long axis blocks out sunlight the rest of the year. Here streaks of sunlight appear on the face and enter both windows of the cave.  This picture was taken at 7:05 PM.

 Unfortunately, Miantonomi's Cave is surrounded by trees that diffuse the light.  Here is the interior of the cave around 6:35 PM. Light is streaming in through the large window.
 The light entered the small window and the second sun dagger appeared at 6:40 PM.
 It got bigger and even took on a slightly birdlike appearance at 6:42 PM.
 Unfortunately, a cloud blocked the sun until 7:06, when this pattern appeared.

This is the final pattern, at 7:30.  A large  patch of  light appears on the end of the projecting stone. This was only a thin streak of light on 4/28.
Then the cave went dark at 7:35.  The time lapse video is at Youtube.
Here is the view from outside the cave.  The small blue box on the ledge is the time lapse camera. I wonder how many centuries passed with Native people watching this display.

This is a complex pattern of light and shadow, altered by surrounding trees and passing clouds.  Two markers of summer solstice may be the light on the face of the slanted boulder, and the large patch of light on the end of the projecting stone. There is also a faint mark on the wall that the sun ray follows as it travels up the wall.
The flat end of the projecting stone, which was illuminated at the end of the display, is shown above.

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