Gustav Spörer
Overview
Spörer was born in Berlin on 23/10/1822. He had already been active in solar research in Berlin for some time and indeed the idea of an Astrophysical Observatory grew out of plans to build a solar observatory under his leadership.
He had earlier, in 1861, discovered a law concerning the variation in latitude of sunspot zones over the course of a solar cycle - Spörer's law - At the start of a cycle, spots occur at latitudes between 30 and 45 degrees. As the cycle progresses, spots appear closer to the equator until, at maximum, the average latitude of the groups is about 15 degrees. After maximum the spots become less common but still approach the equator reaching about 7 degrees. They die out before reaching the equator but, before they do so, spots of a new cycle are seen at higher latitudes. The effects of Spörer's Law can be displayed in a "Butterfly Diagram", although this diagram was only introduced later, by Maunder.
He also independently discovered the Maunder Minimum - a period between
1645 and 1715 when sunspots were virtually non-existant.