Solar rotation. Sequence of 35 optical images taken a day apart, showing the rotation of the Sun's surface. The first image (upper left) was taken on 1st June 2000, and the last (bottom right) on 5th July 2000. The rotation is seen in the movement of dark sunspots from left to right across the solar disc. Different parts of the Sun rotate at different rates. At the equator, the Sun's surface rotates in 25.4 days. Sunspots are cooler areas on the Sun's surface, thought to be caused by interactions within the Sun's magnetic field. They tend to occur in two bands above and below the solar equator.