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Solar Eclipse (Annular), Crater Lake National Park




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Simple Viewing and Photographic Techniques used for the Annular Solar Eclipse

Crater Lake National Park, Oregon - 20 May 2012


On Sunday, 20 May 2012 the Crater Lake area of southhern Oregon was treated with a nice annular solar eclipse of the Sun. The eclipse as seen from Discovery Point, along Crater Rim Road, being just of the eclipse path centerline, (Fig. 1) and near the end of the event. The eclipse starting in Asia and ending in North America (Fig. 2).



Annular Eclipse Centerline near Crater Lake National [1]

Entire path of the annular eclipse of the Sun [2]

(Fig. 1, top) The path centerline for the annular eclipse of the Sun pass just south of the Crater Lake area.(Fig. 2, above) The entire path of the annular eclipse of the Sun. The eclipse starting in Asia and ending in North America, with maximum duration occuring near the international dateline.



Public group viewing the Annular Solar Eclipse from Crater Lake National Park, Discovery Point, Oregon - 20 May 2012 [3]

(Fig. 3) Public group of observers watching the annular solar eclipse of the Sun from Discovery Point at Crater Lake National Park, Oregon on 20 May 2012.


As expected, the local wind speed increased approximately 10-15 minutes prior to maximum eclipse. This was due to a change in local air pressure as the solar umbra (shadow) moved across the surface of the Earth. This is because the umbra produces a slight and momentary cooling effect on the surface of the Earth, as the Sun's radiant energy on the Earth's surface, with on a sunny day is nearly 2,900 watts per square meter is reduced by nearly 85% for a brief moment. The effect of this lost solar energy producing a change in local air pressure, resulting in an increase in wind speed, returning to pre eclipse conditions as the solar umbra (shadow) passes on.



Camera Obscura using a pinhole to project an image of the solar ecplise, made by Crater Lake National Park Ranger Stephanie Carter. [4] Camera Obscura using a pinhole to project an image of the solar ecplise, made by Crater Lake National Park Ranger Stephanie Carter. [5]

Optical ray trace diagram for pinhole projection, or camera obscura. [6]

(Fig. 4, top left) A Pinhole Projection (Camera Obscura) tube, made by National Park Ranger Stephanie Carter from two carboard boxes, was used to help facilitate the viewing of the solar eclipse by those without the necessary filtering. Park McGraw is making manual pointing and tracking adjustments of the long focal length, pinhole aperture. (Fig. 5, top right) Park McGraw adjusting the position of the pinhole aperture, with National Park Ranger Stephanie Carter providing feedback as to when the projected image of the eclipsed Sun is centered upon the projection screen at the rear of the tube. The projection screen at rear of the tube was made from a sheet of white paper. (Fig. 6, above) Pinhole Image Projection and Formation.


The solar filter used.



Simple solar filter used to photograph the Sun [7] Camera and solar filter configuration used to photograph the Sun [8]


(Fig. 7, left) Simple Solar Filter. (Fig. 8, right) How the Solar Filter was configured with the camera.


As .



Solar Eclipse (Annular), Crater Lake National Park, Discovery Point, Oregon - 20 May 2012 [9]

Solar Eclipse (Annular), Crater Lake National Park, Discovery Point, Oregon - 20 May 2012 [10]


(Fig. 9, top) Eclipse image recorded at 6:25:05 PST. (Fig. 10, above) Enhanced Eclipse image recorded at 6:25:05 PST.


The .



[1] Map, Annular Solar Eclipse Centerline, adapted by Park McGraw, 27 May 2012, retrieved 25 May 2012; http://newton.uor.edu/facultyfolder/tyler_nordgren/eclipse/EclipsePublicMap.jpg.

[2] Map, Annular Solar Eclipse, entire path, retrieved 25 May 2012; http://upload.wikimedia.org/wikipedia/commons/5/58/SE2012May20A.png.

[3] Photo, Crater Lake Eclipse Viewers, Discovery Point, Crater Lake National Park, 20 May 2012, Rumi Shiiya, 2012, adapted by Park McGraw, 27 May 2012.

[4] Photo, National Park Ranger Stephanie Carter with camera obscura, and Park McGraw, Discovery Point, Crater Lake National Park, 20 May 2012, Rumi Shiiya, 2012, adapted by Park McGraw, 27 May 2012.

[5] Photo, National Park Ranger Stephanie Carter with camera obscura pinhole side, and Park McGraw, Discovery Point, Crater Lake National Park, 20 May 2012, Rumi Shiiya, 2012, adapted by Park McGraw, 27 May 2012.

[6] Diagram, Pinhole Projection, (Camera Obscura) , 27 May 2012, Park McGraw, 2012.

[7] Photo, Eyeglass Solar Filter by Elcipse Shades, Park McGraw, 27 May 2012.

[8] Diagram, Camera and Handheld Solar Filter Configuration, 27 May 2012, Park McGraw, 2012.

[9] Photo, Annular Eclipse, 20 May 2012, Park McGraw 2012, adapted by Park McGraw, 27 May 2012..

[10] Enhanced Photo, Annular Eclipse, 20 May 2012, Park McGraw 2012, adapted by Park McGraw, 27 May 2012..




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