"a region," late 14c., from Old French plage (13c.), from Late Latin plagia "a plain, shore," noun use of adjective (plagia regio), from plaga "a region, stretch of country" (see pelagic). Astronomical sense is from 1949.
(pläzh) A bright and intensely hot area in the Sun's chromosphere, usually associated with a sunspot. It is typically brighter than its surroundings but may be indistinguishable due to lack of contrast. Plages are sources of strong ultraviolet radiation.