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facula



  1. faculae on the Sun's surface
    A bright area on the face of the Sun, commonly seen near an active region, such as a sunspot, or where such a region is about to form. Faculae, which last on average about 15 days, are best seen in blue light and are not visible at all in H-alpha. They were named by Johannes Hevelius and are thought to be caused by luminous hydrogen clouds close to the photosphere.

  2. A bright spot on the surface of a planet or moon.

Related category

   • SOLAR TOPICS