OSA's Digital Library

Applied Optics

Applied 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)

View Full Text Article

Enhanced HTML    Acrobat PDF (4834 KB)

Browse Journals / Lookup Meetings

Browse by Journal and Year


Lookup Conference Papers

Close Browse Journals / Lookup Meetings

Article Tools



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

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

David K. Lynch, "Visually discerning the curvature of the Earth," Appl. Opt. 47, H39-H43 (2008)

Sort:  Author  |  Year  |  Journal  |  Reset  


  1. R. W. Emerson, Nature: Addresses, and Lectures, new and revised ed. (Houghton, Mifflin, 1884), p. 22..
  2. Piccard is widely believed to be the first. There are many references to his achievement on the Internet, most of them certainly derivative. I contacted the Piccard family and they were aware of the claim but had no hard evidence or literature citation backing it up.
  3. S. W. Bilsing and O. W. Caldwell “Scientific events,” Science 82586-587(1935). [CrossRef]
  4. A brass plaque placed at the Lamont Odett vista point in Palmdale, Calif., by E. Vitus Clampus claims that X-1A pilot Arthur “Kitt” Murray was the first person to see the curvature of the Earth. The plaque does not cite the year or altitude, but, according to the NASA archives, it was probably on 26 August 1954 when Murray took the X-1A to a record-breaking altitude of 90,440 ft (27,566 m).
  5. Entering “curvature of the earth” into the image search using any search engine will find thousands of images. Most photographers place the horizon near the top of the frame in order to capture the scene of interest below the horizon. The resulting barrel distortion produces a pronounced upward (anticlinal) curvature of the horizon that most people incorrectly interpret as the curvature of the Earth.
  6. D. Gutierrez, djgutierrez1@verizon.net (personal communication, 2007).
  7. C. F. Bohren and A. B. Fraser, “At what altitude does the horizon cease to be visible?” Am. J. Phys. 54, 222-227(1986). [CrossRef]
  8. A. P. French, “How far away is the horizon?” Am. J. Phys. Vol. 50, 795-799 (1982). [CrossRef]
  9. E. J. McCartney, Optics of the Atmosphere (Wiley, 1976), Fig, 4.8, p 205.

Cited By

Alert me when this paper is cited

OSA is able to provide readers links to articles that cite this paper by participating in CrossRef's Cited-By Linking service. CrossRef includes content from more than 3000 publishers and societies. In addition to listing OSA journal articles that cite this paper, citing articles from other participating publishers will also be listed.

« Previous Article  |  Next Article »

OSA is a member of CrossRef.

CrossCheck Deposited