Subsuns and rainbows during solar eclipses

Abstract

A photographic observation sequence was obtained of a subsun before, during, and after the total phase of the 2016 solar eclipse. The time-resolved images were obtained from a high-altitude jet aircraft. The image sequence was searched for the possible presence of a solar corona-generated subsun during totality. Although the subsun-creating conditions apparently persisted during totality, the drop in signal intensity compared to the local background prevented its detection. Separately, we document a visual observation from the 1977 total solar eclipse of a rainbow that faded, in the last a few seconds before totality, from being normally multicolored to monochromatic red from water drops then predominantly illuminated by light from the solar chromosphere. A similar transition in the final seconds before, and after, totality is expected to occur for parhelia. The posited short-living monochromatic red parhelion resulting from the momentary illumination of ice crystals by the solar chromosphere is still waiting to be observed. (C) 2020 Optical Society of America