Most of the big observatories have stunning display rooms where you can see photographs taken by the master telescopes. Perhaps there will be a series of pictures of the sun's face, taken several hours or several days apart. This is most interesting when Old Sol's radiant complexion is breaking out in a rash of dark and angry looking sunspots.
In the first picture, the dark rash appears about where you would draw an ear on the face of the sun. A week later, the rash has moved to the center, just about where you would draw a nose for Father Sun. In another week, it is where you would draw the second ear and the next day the rash of sun spots has disappeared from view.
If the rash is very severe, it may last several weeks. In this case, we can expect to see it two weeks later in the place where we saw it in the first picture of the series. The rash o.t sunspots has, of course, traveled all the way around the sun carried by the sun's rotation.
Since it rotates on its axis, the sun has two poles and an equator exactly half way between them. Sunspots occur near the wide waist of the sun and never near the poles. By studying a rash of sunspots we might figure that the sun rotates once in about 28 days but this is only partly true. For the sun rotates at different speeds at different latitudes.
At its equator, the sun rotates once in a little less than 25 earth days. In the latitudes north and south of the equator where sunspots usually occur, it rotates once in about 28 days. In latitudes 75 degrees, nearer the sun's poles, each rotation takes about 33 days.
The sun, like the earth, rotates from the west towards the east. The earth, however, is solid and rotates all in one piece. The sun is made of freely flowing gases; which do not rotate as single unit. A single rotation near the poles takes more than one earth week longer than a single rotation at the equator.