Solar Rotation Activity, Part 2

The purpose of this worksheet is to have you analyze some of the ideas brought up in your class and extend these ideas to answer a new question. Try to answer the questions just as you would answer a classmate who asked them -- it's okay to be informal, but please be descriptive, and draw pictures if it helps you make your point.

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1. Of the following two methods for measuring the rotational period, which do you think should be more accurate? Why?

(a) Choose a spot near the center of the Sun's image, and measure how far this spot moves in one day. Divide this distance into the circumference of the Sun to come up with the number of days it would take to go all the way around.
(b) Count the number of days for a spot to go from the very edge of the image to the center (one-fourth of the way around the Sun), and multiply by four.

2. In method (a) above, why is it important to choose the spot near the center? What would go wrong if you chose a spot near the side of the image?

3. Suppose you have a friend who doesn't believe that the Sun rotates. When you show him the pictures and point out how a spot moves from day to day, he insists that the spot must be a planet orbiting around the sun, not a spot on the sun. How could you convince him otherwise? (The diagram below might be helpful.)