Changing its Spots SDO took a closer look as a barely emerging sunspot group really grew and mushroomed into a large sunspot group over less than three days (Jan. 6-8, 2012). Sunspots are almost always changing, but the speed of growth here was quite striking. Sunspots are cooler, darker regions generated by magnetic forces beneath the Sun's surface. They are often the source for solar storms, although this particular group did not produce any major storms. For a size comparison, the spot on the left of the group is easily larger than Earth.