Summary of sky brightness measurements during eclipses of the sun.

A selected group of measurements of the sky brightness during total solar eclipses is used to determine a standard light curve during the period from no obscuration to totality. It is found that the sky light may be considered as attenuated sunlight up to at least 99.8% obscuration. During totality, the sky light consists of multiply scattered light from outside the umbral region. The effects of solar elevation angle, cloud cover, and albedo and the variability of the light curve during totality are discussed.