Lunar Eclipse 2.20.08 shadow diffraction | Bill Graham

Bill Graham
Location of photo
Bensalem, PA
Date/Time of photo
10:07-11:09 EST
HP 945C digital camera on tripod, not guided, 16 sec exposure, EFL=200 mm, ASA 100
Earth diffraction disk compared to geometric umbra. Sequence of photos of 2/20/08 eclipse taken from 10:07 to 11:09 EST. The photos begin shortly after begin of totality at upper right and totality ends at third from last photo at lower left. Last two photos are partial phase. These photos allow determination of diameter of earth diffraction disk due to bending of light around earth, since eclipse is near edge of geometric shadow. At mid-eclipse, drawing shows earth diffraction disk is 85% of umbra.
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