butterfly diagram

Butterfly diagram. How the distribution of sunspots in latitude changes with time. A representation in graphical form of the way the latitudes at which sunspots appear vary throughout the solar cycle. It was first plotted in 1922 by E. W. Maunder and is also known as the Maunder diagram. On a graph with solar latitude as the vertical axis and time (in years) as the horizontal axis, a vertical line covering one degree in latitude is plotted for each sunspot group centred at that latitude within a Carrington rotation. The result (see illustration) is a pattern reminiscent of butterfly wings, which gives the diagram its popular name.