Solar eclipses as an astrophysical laboratory.

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.