active region

active region of the Sun

Credit: A. Title (Stanford Lockheed Institute), TRACE, NASA.

In solar physics, an active region is a localized volume of the Sun's outer atmosphere where powerful magnetic fields, emerging from subsurface layers, give rise to various short-lived features. These features may include:


  • sunspots and faculae in the photosphere
  • plages, fibrils, and filaments in the chromosphere
  • coronal condensations in the corona.

    Solar flares are also associated with active regions.