Name:    Date:

The Sun

The Sun is easily imaged and sunspots are usually visible in any small telescope. Imaging the sun several days in a row, or perhaps two to three times a week allows observation of sunspots forming and dying as well as their motion while the sun rotates.From this, one can estimate the rate of rotation of the Sun. (Note: The rotation rate is differential; i.e., it rotates at a different speed at the equator than at the poles.)

BE SURE NEVER TO LOOK AT THE SUN THROUGH A TELESCOPE unless adequate precautions are taken. A solar filter may be used to block out a large portion of the sunlight(99.99%) for comfortable viewing. Instead, you can use the procedure described below. DO NOT OBSERVE THE SUN DIRECTLY.

Procedure:

  1. Imaging the Sun:

    2.  

    Try(for the time being) to check the following URL:
    http://www.spaceweather.com/sunspots/doityourself.html

    DO NOT LOOK AT THE SUN THROUGH A TELESCOPE. THE SUNLIGHT WILL INJURE YOU EYES. Using your small Refractor, you can align the telescope to project solar images on a blank paper. Rotate the telescope so the telescope tube makes the minimum shadow on the ground. The eyepiece should point downwards and project the image of the sun onto a blank piece of paper. This is important. You are pointing the telescope backwards. Be sure to tilt the paper so the sun does not shine directly onto it. i.e., you have to keep the paper in the shadow. If the sun shines directly on it the image will be lost in the glare.Your instructor will describe how to do this. It would be helpful to have someone assist you in the imaging process. You should be able to see:

    1. Sketch the image of the sun onto the paper.
    2. Identify any sunspots. How can you tell these are on the sun and not flaws on the paper itself? How do you know these are not spots on the lenses?
    3. Record the date, and time of the obsevation, and the sky conditions.
    4. Sketch as much detail as possible. Do you see limb darkening too?
    5. Is there any color visible? Is it uniform? Any bright areas?
    6. Come back in a day or two and see if the sunspots have moved. Is it possible to determine the rotation rate of the sun? You may want to do this repeatedly over a course of a month or so.
  2. Discussion Questions:

    3.  

     

    You'll need to research the www to find answers to the following:

    1. Does the sun rotate on its axis? How long would it take for a sunspot to move from one side of the disk to the other? Explain.
    2. Explain the 11 year cycle.
    3. Sometimes Mercury or Venus will be directly between the Earth and the Sun. They'll appear as a black dot on the Sun. How could you tell if the black dot you are observing is Venus or Mercury?
    4. What is limb darkening? Describe what you saw.
    5. how do sunspots affect radio communication and the aurorae?
    Try the following URL: http://bang.lanl.gov/solarsys/edu/sunspots.htm

 

A great web site you need to check because it has SOHO and latest images of the sun regardless of our weather is: http://www.spaceweather.com/

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