The green flash is a rare, brief optical event of green, yellow, and sometimes blue that colors the horizon, occurring at sunrise or sunset most often in the western U.S. Refraction and dispersion ...

Just as the sun slips behind the Chilean Andes, it seemed to send up a tiny emerald flare. The photograph, taken from Cerro Pachón in Chile by NOIRLab Audiovisual Ambassador Petr Horálek, captures a ...