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Solar eclipses as an astrophysical laboratory

Abstract

Observations of the Sun during total eclipses have led to major discoveries, such as the existence of helium (from its spectrum), the high temperature of the corona (though the reason for the high temperature remains controversial), and the role of magnetic fields in injecting energy into—and trapping ionized gases within—stellar atmospheres. A new generation of ground-based eclipse observations reaches spatial, temporal and spectral-resolution domains that are inaccessible from space and therefore complement satellite studies.

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Figure 1: The geometry of eclipses.
Figure 2: The corona at totality.
Figure 3: The paths of total eclipses, 2001–25.
Figure 4: The 1 August 2008 eclipse from the ground and from space.
Figure 5: Correcting for the large dynamic range in coronal intensities.

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Acknowledgements

The author is glad to acknowledge his mentors and eclipse colleagues over the 50-year period that he has been observing his 48 solar eclipses, including D. H. Menzel, J. P. Schierer, B. A. Babcock, S. P. Souza, V. Rušin, M. Druckmüller, M. Saniga and others; L. Golub, R. W. Noyes, E. H. Avrett and H. Zirin for other aspects of solar physics; F. Espenak for eclipse-path calculations; and generations of undergraduate students from Williams College who have participated in expeditions and/or studied eclipse data. At various times, his eclipse research has been supported by the Committee for Research and Exploration of the National Geographic Society, the Astronomy and Atmospheric Sciences Divisions of the National Science Foundation, and the Heliophysics Division of NASA, as well as by Williams College. He thanks M. Brown and the Division of Geological and Planetary Sciences of the California Institute of Technology for hospitality during the writing of this Review. The preparation of the article benefited from NASA's Astrophysical Data System.

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Correspondence to Jay M. Pasachoff.

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Pasachoff, J. Solar eclipses as an astrophysical laboratory. Nature 459, 789–795 (2009). https://doi.org/10.1038/nature07987

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