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Applied Optics

Applied Optics

APPLICATIONS-CENTERED RESEARCH IN OPTICS

  • Editor: James C. Wyant
  • Vol. 47, Iss. 34 — Dec. 1, 2008
  • pp: H39–H43

Visually discerning the curvature of the Earth

David K. Lynch  »View Author Affiliations


Applied Optics, Vol. 47, Issue 34, pp. H39-H43 (2008)
http://dx.doi.org/10.1364/AO.47.000H39


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Abstract

Reports and photographs claiming that visual observers can detect the curvature of the Earth from high mountains or high-flying commercial aircraft are investigated. Visual daytime observations show that the minimum altitude at which curvature of the horizon can be detected is at or slightly below 35,000   ft , providing that the field of view is wide ( 60 ° ) and nearly cloud free. The high-elevation horizon is almost as sharp as the sea-level horizon, but its contrast is less than 10% that of the sea-level horizon. Photographs purporting to show the curvature of the Earth are always suspect because virtually all camera lenses project an image that suffers from barrel distortion. To accurately assess curvature from a photograph, the horizon must be placed precisely in the center of the image, i.e., on the optical axis.

© 2008 Optical Society of America

OCIS Codes
(000.2060) General : Education
(000.2700) General : General science
(010.1290) Atmospheric and oceanic optics : Atmospheric optics
(010.7295) Atmospheric and oceanic optics : Visibility and imaging

History
Original Manuscript: April 9, 2008
Manuscript Accepted: April 28, 2008
Published: July 25, 2008

Citation
David K. Lynch, "Visually discerning the curvature of the Earth," Appl. Opt. 47, H39-H43 (2008)
http://www.opticsinfobase.org/ao/abstract.cfm?URI=ao-47-34-H39

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