The Smithsonian Astrophysical Observatory Solar Constant Program

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Provides a history of the Smithsonian Astrophysical Observatory and its solar constant measurement program, 1902-1962, developed by Charles Greeley Abbot. Discusses the debate over whether the data proved there was solar variability, and reanalyses the data to resolve the debate. Concludes solar constant appears to be constant to within about 0.1% and that it is independent of solar variability.


  • Abbot, C. G (Charles Greeley) b. 1872
  • Smithsonian Astrophysical Observatory


Smithsonian Institution History Bibliography


Scientific Figures, Tables and a Reference section accompany the article.

Contained within

Reviews of Geophysics and Space Physics Vol. 17, No. 3 (Journal)

Contact information

Institutional History Division, Smithsonian Institution Archives, 600 Maryland Avenue, S.W., Washington, D.C. 20024-2520,


May 1979


  • Astrophysics
  • Secretaries
  • Smithsonian Institution
  • Solar constant

Physical description

pp. 427-458

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