On the Duration of the Spöerer Minimum

Eun-Hee Lee [ehl77@obs.yonsei.ac.kr], Yonsei University Observatory, Seoul 120-749, Korea.

            The great minima, when sunspot activity dropped to unusually low level, happened several times during the last 1000 years and have a close elation with cold weather period on the earth. However the duration of the great minima was not known exactly, except Maunder minimum(1645-1715) so called little ice age in Europe. Because the continual sunspot observation by the telescope began from 1610. In this study we have examined on the duration of the spöerer minimum, using the proxy data such as the historical auroral records and cosmogenic evidences.