The Sun

1995 The Regents of the University of California


Internet Information

If you are ready to investigate Mr. Sol's rotation, you may click here for a list of dates for which images in H-alpha or X-ray are available. Choose full disk images and select several images that show some type of surface feature like a sunspot, and then check images daily for a week or so.

We are curious if you will be able to tell the direction of rotation and the time it takes for the Sun to make one complete rotation.


  1. Keep careful records of all Sun images you are going to work with.

  2. You can start with the image of the Sun on January 1, 1996. Notice the dark splotches?
  3. Those areas are sunspots, and although they are not permanent, they last long enough for us to be able to follow them as they move with the gaseous surface of the Sun.
  4. Notice and remember where these spots are.
  5. Click another date to get an image of the Sun a couple of days later, on January 6, 1996, for example. Did the spot move? (Since North is up in these pictures, you should be able even to tell which direction they moved.)
  6. Begin collecting data by:
  7. Calculate the angular velocity and the period of rotation of the Sun by one of the methods we've discussed previously.
  8. You can also take a look at an animation (7.2Mb) showing the rotation of the Sun from January 1 through November 30, 1996. This movie has one image for each day. As you can see this means that the speed of rotation that you are seeing is not representative of reality, but you can still calculate the period of rotation from this animation.


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