Solar plage

A plage (/pleɪdʒ/) is a bright region in the chromosphere of the Sun, typically found in and around active regions. The term plage is poetically taken from the French word for "beach".

Plage often appear as bright patches around active regions in the chromosphere. Plage are commonly observed around or surrounding sunspots, as both are phenomena associated with active regions.

Plage map closely to the bright spots known as faculae in the photosphere below, but the latter have much smaller spatial scales. Accordingly, plage occurs most visibly near active regions. Faculae have a strong influence on the solar constant, and the more readily detectable plage areas traditionally are used to monitor this influence. In this context, "active network" consists of plage-like brightenings extending away from active regions as their magnetism appears to diffuse into the quiet Sun, but constrained to follow the network boundaries.

Because faculae can be explained with the strictly photospheric "hot wall" model,[1] the actual physical relationship between plage and faculae is not clear.