On the Existence of the 11-Year Cycle in Solar and Auroral Activity before and during the So-Called Maunder Minimum

Abstract

This paper deals with visual auroral data from Central Europe (φ: 53-48°N) during the years 1545 to 1715. The reality of these observations has been discussed in detail. From the observations it can be demonstrated that the 11-year-cycle in solar and auroral activity exists during this period. Table 2 gives a compilation of auroras per year; the table shows that in almost every year-before and during the Maunder Minimum-auroras have been observed in Middle Europe. Because they are indicators of solar geomagnetic activity it follows that no unusual variability in solar or geomagnetic activity is indicated.