What are sunspots?
Sunspots are visibly darker regions on the surface of the Sun. These "blemishes" on the photosphere are slightly cooler than the surrounding 6000 C surface, but still are very hot at ~4500 C. Sunspots often come in pairs, leading scientists to believe they are connected by magnetic field lines under the surface of the photosphere.
Sunspots have been found to appear following a semi-predictable timeframe now referred to as a "solar cycle". This cycle was first proposed by scientist Samuel Schwabe. The sun experiences a cycle (see films posted at right) that is ~11 years in duration.
A little history of Sunspot recording:
Sunspots were first recorded by Chinese observers, and later (more famously) recorded by Galileo Galilei. His ink drawings of spots helped to illustrate that the Sun itself rotates on its axis (like Earth). Earlier drawings by John of Worcester were among the first illustrated records of these solar phenomenae. Early solar photography by Foucault and Fizeau provided the first known photographic images specifically recording sunspot features.