They typically last for several days, although very large ones may live for several weeks. Sunspots are magnetic regions on the Sun with magnetic field strengths thousands of times stronger than the Earth's magnetic field.
Sunspots usually come in groups with two sets of spots.
One set will have positive or north magnetic field while the other set will have negative or south magnetic field. The field is strongest in the darker parts of the sunspots - the umbra. The field is weaker and more horizontal in the lighter part - the penumbra. Unfortunately, the more recent data is given in a different format from the original and there are definite changes in the reported parameters from the different sources. In an effort to append the RGO data with the more recent data I have reformated the USAF and NOAA data to conform to the older RGO data format.