The drift of the average latitude of sunspots towards the Sun’s equator during the 11-year sunspot cycle. Spots of a new cycle are generally located at latitudes 30–40° north or south, but over the course of the cycle the average latitude decreases to 5–10°, as demonstrated by the butterfly diagram. The ‘law’ is named after G. F. W. Spörer, but was actually first noticed by R. C. Carrington.