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The sky polarization pattern during solar eclipse totality shifts from the usual daytime clear-sky pattern, with maximum polarization in an arc located 90° from the Sun, to one with maximum polarization slightly above the horizon in a ring nominally concentric about the zenith. A sequence of 9 visible-wavelength all-sky images are shown throughout totality for the 21 August 2017 solar eclipse from a site near Rexburg, ID USA (43.8294°N, 111.8849°W). A neutral region appeared in the southwest quadrant of the all-sky images, directly opposite the eclipsed Sun, and evolved in size and radial position throughout the 2 min 17 s of totality.
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Extended visual range: an observation during a total solar eclipse
Solar eclipses are magnificent natural phenomena during which the sun is obscured by the moon. Besides the unique opportunity of studying the solar corona and immediate vicinity of the sun, an eclipse also leads to a darkened daytime sky with sunset colors and many other fascinating phenomena. Here we focus on how the daytime horizontal visual range changed during the duration of the solar eclipse of 21 August 2017, observed from Rexburg, Idaho, USA. Close to totality the eastern horizon for a short time period showed the contours of the Grand Teton Mountains from distances between about 80 km to 90 km. We show and discuss photographic images that show the visual range during totality being significantly extended beyond the visual range in most of the partial phase before and after totality, which was below 80 km when the mountains could not be seen by the naked eye. This phenomenon of an extended visual range can be explained in terms of a simple model for the daytime visual range. This model, which will be explained in this presentation, nicely reproduces the observations and also predicts other phenomena; for example, it predicts that similar phenomena may be observed if part of the line of sight close to the observer is in deep shade of a thick cloud cover. The presentation will tie these observations and their explanation to the teaching of optical scattering and atmospheric optics.
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- Award ID(s):
- 1757351
- PAR ID:
- 10158892
- Date Published:
- Journal Name:
- Proc. SPIE 11143, Fifteenth Conference on Education and Training in Optics and Photonics: ETOP 2019
- Page Range / eLocation ID:
- 33
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Conference Paper:
- https://doi.org/10.1117/12.2523167
