The sun occasionally undergoes the so-called grand minima , in which its magnetic activity , measured by the number of sunspots , is suppressed for decades .
The most prominent grand minima , since the beginning of telescopic observations of sunspots , is the Maunder minimum ( 1645–1715 ) , when the sunspots became rather scarce .
The mechanism underlying the grand minima remains poorly understood as there is little observational information of the solar magnetic field at that time .
In this study , we examine the records of one candidate aurora display in China and Japan during the Maunder minimum .
The presence of auroras in such mid magnetic latitudes indicates the occurrence of great geomagnetic storms that are usually produced by strong solar flares .
However , the records of contemporary sunspot observations from Europe suggest that , at least for the likely aurora event , there was no large sunspot that could produce a strong flare .
Through simple theoretical arguments , we show that this geomagnetic storm could have been generated by an eruption giant quiescent filament , or a series of such events .