Lesson: How Are Magnetic Fields Related To Sunspots?
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
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
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.)
- Computers for student use with web browser and internet access
OR color print-outs of the images from
SOHO-EIT OR color transparencies of the images for a
teacher directed lesson.
- Duplicated copies of the activity sheets for students.
- One plain sheet of paper per student for drawing images.
Type of Activity:
- Student-centered:Observation using images from SOHO instruments.
- Positioning sunspots on a map of the sun.
- Do the Pre-Activity here or a similar activity.
- Print and duplicate copies of the Student Activity.
- 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.
How Are Magnetic Fields Related To
Directions: Using the SOHO images, complete the following
- 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.
- Fold the sheet of plain paper in half crosswise and title the top
half, ULTRAVIOLET SUN.
- 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
- 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.
- What could you conclude about these three areas as observed by the
SOHO instrument on
Sept. 11, 1997?
- Label the magnetic field lines on your ULTRAVIOLET SUN drawing.
- 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.
- 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
- Label the NORTH and SOUTH poles on your ULTRAVIOLET SUN drawing.
- Draw a dotted line across the center of the sun where the sun's
equator would be.
- 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?
- 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.)
- 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
- Draw what you see in the Visible Light image from SOHO on the
bottom half of your drawing paper. Title this drawing: VISIBLE
- What are these dark spots, appearing in pairs on the surface of
- Label the spots on the drawing with the correct term and title
the drawing with the same term.
- Explain how magnetic fields on the sun are related to
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.
- 1 bar magnet sealed inside a sandwich bag
- 2 sheets of white paper
- 1 sheet of transparency film
- small cup of iron filings
- Place the bar magnet between a sheet of white paper and the
- Sprinkle a light layer of iron filings across the bar magnet on
the transparency film.
- Observe the pattern made by the iron filings around the bar
- If you don't get a good pattern the first time, pour the filings
back into the cup and try again.
- 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.
- Pour the iron filings back into the cup and return the
Links To Lesson Extensions
Connections to National Standards: