The Fabled "Green Flash" at sunset or sunrise can sometimes be seen on crystal-clear days in January. At the instant the sun's upper rim is last visible at sunset, and also at the instant when it is first seen at sunrise, a flash of emerald-green color may be observed, especially on a flat horizon. Physicists explain this peculiar phenomenon as due to color-dispersion (as in a prism) and scattering of sunlight through the earth's atmosphere. Binoculars (or a small telescope) are helpful in spotting it. For green-flash hunting at sunset, any site with a view of the ocean horizon suffices. For the sunrise green flash, any spot overlooking the low desert (Sunrise Highway in the Laguna Mountains, for example).