Документ взят из кэша поисковой машины. Адрес оригинального документа : http://www.wdcb.ru/stp/data/solar.act/sunspot/info.ssn Дата изменения: Mon Jan 18 16:46:43 2010 Дата индексирования: Tue Oct 2 01:53:54 2012 Кодировка:

In 1848 the Swiss astronomer Johann Rudolph Wolf introduced a daily measure-
ment of sunspot number. His method, which is still used today, counts the
total number of spots visible on the face of the sun and the number of groups
into which they cluster, because neither quantity alone satisfactorily meas-
ures sunspot activity.

An observer computes a daily sunspot number by multiplying the number of
groups he sees by ten and then adding this product to his total count of in-
dividual spots. Results, however, vary greatly, since the measurement strong-
ly depends on observer interpretation and experience and on the stability of
the Earth's atmosphere above the observing site. Moreover, the use of Earth
as a platform from which to record these numbers contributes to their varia-
bility, too, because the sun rotates and the evolving spot groups are distrib-
uted unevenly across solar longitudes. To compensate for these limitations,
each daily international number is computed as a weighted average of measure-
ments made from a network of cooperating observatories.

Today, much more sophisticated measurements of solar activity are made
routinely,but none has the link with the past that sunspot numbers have.