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Astro*Dictionary by Michael Erlewine





2 articles for "Sunspot"

Sunspot [Astro*Index]

Sunspots are relatively cool regions of the Sun's photosphere, and are large enough to be visible to the naked eye. They are regions of high magnetic fields with a temperature of 4,000°K, some 2,000°K cooler than the surrounding area. They provide a visible indicator of the solar magnetic cycle, which peaks every eleven years. The solar magnetic field has been shown to affect radio reception on Earth, and also, to affect living organisms.

See also: ♦ Solar Cycle ♦ Photosphere
Sunspot Cycle [DeVore]

The phenomenon of Sunspot cycles is one which has increasingly engaged the atteention of astrophysicists for more than two centuries. Useful records of the sunspot cycle are available from 1610 to the present day. For a long time the cycle was said to be of a duration of 11.3 years, but more recently it has been noted that successive eleven-year cycles produce similar but opposite phenomena, and that a complete cycle is of a duration of 22.6 years. It has also been noted that while the Sun's surface is hotter at times of sunspot maxima, the Earth's land surface is cooler, apparently due to the increased cloudiness that attends the phenomena. It is also found that magnetic disturbances in the Sun — are reflected on the Earth with increased display of the aurora boreali; and magnetic disturbances that interrupt telegraphic service. Economic cycles are also found to correspond with the Sunspot Cycle. Trees grow more during the years of Sunspot maxima, when ultra-violet radiation increases by as much as 30 Per cent. Some plant life grows better with an excess of ultra-violet light, while other species thrive better on an excess of infra-red rays. Ellsworth Huntingdon, of Yale University, says solar radiation affects the health and behavior of man. Harlan E. Stetson, of Massachusetts Institute of Technology, finds business activity, output of automobiles and new building construction follow the Sunspot cycle. For lack of reliable data on weather conditions, Dr. William Herschel used the price of wheat as an index on which to base his observations of this and similar cosmic cycles. Thus sciences establish the fact that man is influenced by cosmic phenomena, and the step to recognition of the validity of astrological influences has only the hurdle of prejudice to overcome before it is accorded scientific recognition.

See also: ♦ Astronomy ♦ Sun ♦ Sunspot ♦ Supercycle


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