Double sunset

A double sunset is a rare astro-geographical phenomenon in which the Sun appears to set twice in the same evening from a particular viewing point, and a double sunrise can occur in a similar way; such phenomena may have carried significance in prehistoric times and have been discussed in the context of archaeoastronomy by researchers such as Alexander Thom. One documented cause is a solar eclipse whose most significant phase is observed shortly before or after the geometrical sunset, so that an observer sees two moments with the same illumination level typical of sunset or twilight; a double sunset caused this way, also called a double sunrise, double dusk, or double dawn, was reported in Shaanxi Province on April 21, 899 BC, following a morning annular solar eclipse. This description is adapted from Wikipedia contributors under CC BY-SA 4.0; changes were made. https://creativecommons.org/licenses/by-sa/4.0/