| Visually discerning the curvature of the Earth. | |
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MedLine Citation:
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PMID: 19037349 Owner: NLM Status: PubMed-not-MEDLINE |
Abstract/OtherAbstract:
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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 degrees ) 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. |
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Authors:
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David K Lynch |
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Publication Detail:
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Type: Journal Article |
Journal Detail:
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Title: Applied optics Volume: 47 ISSN: 1539-4522 ISO Abbreviation: Appl Opt Publication Date: 2008 Dec |
Date Detail:
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Created Date: 2008-11-27 Completed Date: 2009-01-28 Revised Date: - |
Medline Journal Info:
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Nlm Unique ID: 0247660 Medline TA: Appl Opt Country: United States |
Other Details:
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Languages: eng Pagination: H39-43 Citation Subset: - |
Affiliation:
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Thule Scientific, P.O. Box 953, Topanga, California 90290, USA. thule@earthlink.net |
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From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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