In the seventeenth century, they exhibited a long quiescent period called the Maunder minimum.
In the seventeenth century, they exhibited a long quiescent period called the Maunder minimum. The similar Spoerer minimum occurred in the fifteenth century, and earlier quiet intervals have been inferred. Since the beginning of the eighteenth century, variations in their number have shown the fairly regular period, noted by Samuel Heinrich Swabe, of 11 years. FTP, name these most-visible signs of solar activity.
In the seventeenth century, they exhibited a long quiescent period called the Maunder minimum.
{sunspots}