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EARTH SCIENCE > SUN-EARTH INTERACTIONS > SOLAR ACTIVITY > SOLAR ACTIVE REGIONS

Definition:
A region of the solar atmosphere from the photosphere to the corona that
develops when strong magnetic fields emerge from inside the sun. The magnetized
realm in and around the sunspots is called an active region. Radiation from
active regions is enhanced when compared to neighboring areas in the
chromosphere a corona over the whole electromagnetic spectrum. They may last
from a few hours to a few months. They are the sites of intense explosions,
called solar flares.


Reference:
the Cambridge Encyclopedia of the Sun, The Cambridge University Press,
Cambridge, CB2, 2RU, UK, 2001.