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EARTH SCIENCE > SUN-EARTH INTERACTIONS > SOLAR ACTIVITY > SUNSPOTS
Definition:
An area seen as a dark spot on the PHOTOSPHERE of the sun. Sunspots
are concentrations of magnetic flux, typically occurring in bipolar
clusters or groups. They appear dark because they are cooler than the
surrounding photosphere. Sunspots are classified as to their group
characteristics (called the Zurich Sunspot Classification; older sunspot
counting schemes may have used the Wolf Sunspot Number classification).
Satellite observations of the sun (notably by the ACRIM and ERBE sensors)
have demonstrated a correlation between sunspot luminosity changes and
sunspot numbers - a possible influencing factor in Earth's climate
dynamics.
Reference:
On-Line Glossary of Solar-Terrestrial Terms from the NOAA Space Environment
Laboratory. http://www.ngdc.noaa.gov/stp/GLOSSARY/glossary.html
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