Lesson: How Are Magnetic Fields Related To Sunspots?

(Grades 6-8)

Teacher Information

Galileo was the first European that we know of to observe the sun using a telescope. He recorded observations of sunspots in the seventeenth century. Sunspots are dark, irregularly shaped areas which can sometimes be observed on the surface of the sun. They appear dark because they are about 2000° C cooler than the surrounding sun's surface. Their strong magnetic field inhibits convection of heat to the surface. Sunspots can vary in size from 16 km to 160,000 km.

Sunspot activity goes up (from minimum to maximum) and down (from maximum to minimum) in an eleven year cycle. Communication systems on earth and satellites are affected by sunspot activity.

Sunspots often appear in pairs in which one is like the north pole of a magnet and the other is like the south pole of a magnet. The two poles (sunspots) are linked by loops of magnetic field which arch through the sun's corona.

It should be made clear to the student that the images used in this lesson came from the SOHO spacecraft. The ultraviolet radiation emitted by the sun can only be observed from space. The EIT instrument on SOHO produced the ultraviolet images used in the lesson.

Activity: How Are Magnetic Fields Related To Sunspots?

(Students will discover that sunspots are the result of intense magnetic forces on the photosphere of the sun using images from the SOHO satellite.)

Materials:

Type of Activity:

  Procedure:

  1. Do the Pre-Activity here or a similar activity.
  2. Print and duplicate copies of the Student Activity.
  3. Print student copies of the SOHO images OR print transparencies of the SOHO images OR have computers for student use set with the SOHO images ahead of time.

Student Activity:

How Are Magnetic Fields Related To Sunspots?


Directions: Using the SOHO images, complete the following activity.


  1. Observe the image labeled "Ultraviolet Sun". Look for three areas arranged in a triangle pattern. Each of the three areas has looping lines connecting two bright spots.

  2. Fold the sheet of plain paper in half crosswise and title the top half, ULTRAVIOLET SUN.

  3. On the top half of the paper, draw a "sun map" placing each of the areas in their corresponding place from the "Ultraviolet Sun" image. Each area should include the bright spots and their connecting loops.

  4. Is the looping pattern at each area the same as the magnetic field pattern you observed around the bar magnet in the "I'm Strongly Attracted" activity? Explain.

     

  5. What could you conclude about these three areas as observed by the SOHO instrument on
    Sept. 11, 1997?

     

     

  6. Label the magnetic field lines on your ULTRAVIOLET SUN drawing.

  7. Next observe the SOHO image labeled "Magnetic Field". This image, called a magnetogram, was taken by a different instrument on SOHO, but at the same time as the Ultraviolet(UV) image. It shows black and white spots occuring in pairs. The spots are actually like the north and south poles of a magnet. The south pole appears black and the north pole appears white against the gray background.

  8. Compare the magnetogram to the UV image. What is similar about the bright areas in the UV image and the black/white areas in the magnetogram?

     

     

     

  9. Label the NORTH and SOUTH poles on your ULTRAVIOLET SUN drawing.

  10. Draw a dotted line across the center of the sun where the sun's equator would be.

  11. Notice the positioning of the black versus the white poles in the magnetogram. Are the black poles east or west of the white poles in the northern hemisphere of the sun?

     

  12. Observe the SOHO image labeled "Intensity of Visible Light". This is what the sun looks like to us humans. (NEVER LOOK DIRECTLY AT THE SUN. It can be observed using a pin hole image.)

  13. Compare the Visible Light image to the UV image and the magnetogram. What is similar about the spots on this image, the bright areas in the UV image, and the black/white spots on the magnetogram?

     

     

     

  14. Draw what you see in the Visible Light image from SOHO on the bottom half of your drawing paper. Title this drawing: VISIBLE LIGHT SUN

  15. What are these dark spots, appearing in pairs on the surface of the sun?

     

  16. Label the spots on the drawing with the correct term and title the drawing with the same term.

  17. Explain how magnetic fields on the sun are related to sunspots.

 

 

 

 

Pre-Activity: I'm Strongly Attracted!

Purpose: To observe the lines of force around a bar magnet. May be done as a demonstration by placing the magnet between two sheets of transparency film on an overhead projector.

Materials:(per student)

Procedure:

  1. Place the bar magnet between a sheet of white paper and the transparency film.
  2. Sprinkle a light layer of iron filings across the bar magnet on the transparency film.
  3. Observe the pattern made by the iron filings around the bar magnet.
  4. If you don't get a good pattern the first time, pour the filings back into the cup and try again.
  5. Draw the pattern made by the iron filings on the second sheet of paper. The pattern made by the iron filings shows the magnetic lines of force of the magnet.
  6. Pour the iron filings back into the cup and return the materials.

 

Links To Lesson Extensions


Connections to National Standards: