SOLAR MUSIC - HELIOSEISMOLOGY
Active Learning Exercises in Planetary
and Solar Astronomy
National Optical Astronomy Observatories
Volume 1, Number 1
NEW! Download an Updated Version of this module in PDF format.
This lesson module was written as part of a NASA IDEA grant
titled Active Learning Exercises in Planetary and Solar Astronomy for
K-3 Students. NOAO astronomers worked with students and teachers of
the Satori School in Tucson, AZ, to present eight topics in the elementary
classrooms. Each presentation included a discussion with the astronomers
and a hands-on, active learning exercise. This module, Solar Music -
Helioseismology, encourages the students to realize you can learn
about an object by listening to it. Astonomers listen to the Sun's
heartbeat to learn about the inside of the Sun.
This module was developed by NSO astronomer Dr. Frank Hill and is
intended to be a resource for other astronomers venturing into
classrooms. Please contact the NOAO Educational Outreach Office
(firstname.lastname@example.org) if you would like more information about this module
or others developed through this program.
We used the following 5 color slides for this lesson; Click the images below for a larger, more detailed image [28 to 84K].
Slide 1: Image of actual solar surface
Slide 2: Computer image of slice through sun showing how sound bounces
Slide 3: Computer image of cutaway of sun showing up and down pattern
of one solar musical note
Slide 4: Image of actual solar surface showing the up and down pattern
of all 10 million solar musical notes together at one instant
Slide 5: Image of the "keyboard" of solar music.
Today we would like to teach you about solar music. The sun is filled
with sound, and we can learn about its insides by studying this sound.
In fact, this is the ONLY way we can learn about its inside because
the light we see from the sun comes only from its outside. This picture
shows how the outside of the sun looks to us (show slide #1). But,
this picture does not tell us anything about the inside of the sun.
Thatís because the picture was made using light that comes only from
the outside of the sun. Since the sound is inside the sun underneath
the part we can see, we can use sound to learn about the inside of
Have any of you ever heard the sun? (If they answer "yes", ask them
what it sounded like. They may say it sounds like a bird or a rooster,
since sunrise generally wakes the birds up. Respond to this answer
by saying that the sun causes the birds to wake up and chirp, but
that is not solar music.) Whether they answer "yes" or "no"
will be playing a recording of solar sound for you in a little while.
Have any of you heard echoes? Where? (The most likely answer will
be "outdoors at a canyon", but ask them if they have heard echoes
anywhere else. The answer you are looking for is "inside a room.")
Just like sound echoing all around in a room or a concert hall, sound
is bouncing all around and echoing inside the sun. Here is a picture
created with a computer that shows how sound echoes inside the sun.
(show slide #2).
Sound is a vibration, it moves things up and down, back and forth.
I have a Slinky here, and I need some help to show you how vibrations
move things back and forth. (Get a helper to hold down one end of
a slinky on a desk top. Take the other end, and shake it horizontally
once to get a wave traveling down to and reflecting off the stationary
end.) Did you see how the vibration moved the Slinky back and forth?
Also, did you see how the vibration bounced off the end that was being
held down? The bouncing is what causes echoes, and it also happens
inside the sun when the sound hits the surface like in the picture.
Also, you can actually see the vibration because it makes the Slinky
The sun is like a huge musical instrument. It rings like a bell, and
vibrates like an organ pipe. Does anybody know how many keys or musical
notes a piano has? (Answer is 88). Just like a piano has 88 keys or musical
notes, the sun has 10 million keys or notes. Astronomers are measuring the
solar music in order to determine what its heart is like. This is like
listening to a song to understand the singer. Here is a picture made with
a computer showing the pattern of up and down movement from a single solar
musical note. (show slide #3) The red and blue colors were put into the
picture so you can tell which parts of the sun are moving up (blue), and
which are going down (red).
Since the vibrations of the solar sound make parts of the outside of the
sun move up and down, astronomers can study the sound by looking at the
sun. This is good, since there is no air between the sun and the Earth and
so there is no way for us to actually hear the sound. But, we can use
special cameras to watch the outside of the sun move up and down. Here is
a snapshot of the outside of the sun showing the up and down areas from
all 10 million solar musical notes (show slide #4).
This picture (show slide #5) is a way for astronomers to sort out
and look at all 10 million notes of the solar music at once. This
picture sort of looks like the rainbow pictures you saw earlier, and
is really a spectrum of sound rather than light from the sun. You
can see a bunch of dots at the left side of this picture. These dots
are individual solar notes, like the keys on a piano keyboard. At
the right of the picture, the notes blend together and you can't see
them very well.
Now, I am going to play an audio cassette of solar sound for you.
This cassette was made with a computer using a few of the notes in
the last picture I showed you. You can't really dance to it, but it
tells us a lot about the inside of the sun.
You can download sound files of the sun from Stanford Solar Center's The Singing Sun.
Astronomers can get information about the inside of the sun because
different objects have different sounds. The way things are changes
how they will sound. I am now going to teach you some of the things
we can learn about objects by listening to the sounds they make. I
will be using some things called musical triangles.
Here are three musical triangles (Get 3 students at the front to hold
up the 3 different size triangles).
- What do you notice about them? What is different about them?
- They are all different sizes
- Which one do you think will make the highest musical note?
- The smallest one
- Which one do you think will make the lowest musical note?
- The largest one
- Do you think the musical note of this (middle) triangle will be higher
or lower than this (smallest) one?
- Do you think the musical note of this (middle) triangle will be higher
or lower than this (largest) one?
Listen again as I play all three of them in size order (Do it a few
times) Now, close your eyes, and listen as I play the three triangles
in some order. I want you to listen, and then tell me what size order
I played them in (i.e. middle, large, small) Notice that you could
tell me what the size of the triangle was just by listening to it
without having to see it! The size of the triangle affects how it
sounds. In general, large things produce lower musical tones than
small things. A chihuahua dog has a higher pitched bark than a St.
Next, I will show you how attaching something to the triangle changes
the way it sounds. Here is the small triangle again, and here is another
small triangle just like this one except I have attached a small clip
to it. Here's the sound of the triangle without anything attached.
(Strike the small triangle without the clip) Now, here's the sound
with the clip attached. (strike the triangle with the clip attached)
- How did the two sound different?
- The one with the clip attached sounds "dull" or "muffled"
compared to the "bright" ringing tone of the unclamped triangle.
The sound has changed because a lot of the tones made by the unclamped
triangle have been removed by the clamp. Close your eyes and tell
me if I have struck the clamped or the unclamped triangle. Notice
that you could tell me if something extra was attached to the triangle
just by listening to it.
Finally, I will show you that a spinning triangle sounds different
from one that is standing still. Here's the sound of a triangle standing
still. (Ring the middle triangle) Now I am going to wind this rubber
band up and spin the triangle after I hit it. (Do it but PRACTICE
BEFORE THE LESSON!)
- What do you notice that is different about the sound?
- The spinning triangle will produce a wavering tone whose loudness
seems to go up and down.
The sound is different because if something makes a sound while it
is moving, it changes the tone of the note heard by someone standing
still. You may have noticed that the pitch of a police siren changes
as the police car passes you. It's the same thing. Close your eyes
and tell me if I am spinning the triangle. Moving things sound different
than when they are standing still.
Bottle Harmonica: Here, the students will construct musical
instruments using plastic bottles filled with water. Organize the students
into groups of 2 or 3. Distribute the bottles, 1 to each student (2-3 per
group). Have the students fill the bottles with various levels of water.
Then have them blow across the bottles and ask them what they notice about
the sounds that the bottles make. They should notice that when there is
more water in the bottle, the pitch of the sound is higher. If they have
different size bottles, have them blow across the empty bottles and again
ask them what they notice about the sounds. Smaller bottles make higher
Slinky Vibrations: Have the students experiment with making
waves in Slinkies. Stretch a Slinky across a desk, and have one student
hold down an end. The other student shakes the free end of the Slinky in
various ways to create different wave patterns. Have them first try a
single shake so a pulse bounces off the stationary end. Then they can vary
the frequency of the shaking to create different harmonics. Ask them to
notice how the number of bends in the Slinky changes as they shake the
Slinky faster. There will be more bends as they go faster. Be prepared to
untangle Slinkies! It is possible to set up a standing wave that seems to
Ask the students what they have learned today. Re-emphasize that the
sound made by objects tells us something about them. For example,
big things (triangles, bottles, dogs) sound lower in pitch than small
things. Mention again that the sun is filled with sound, and that
astronomers are listening to it to understand what's going on inside
For further reading you may begin with the following sources:
- Browne MW. "Deep solar rumblings may offer key to sun's inner
structure." The New York Times, B5, 24-Oct-95.
- Leibacher JW, Noyes RW, Toomre J and Ulrich RK. "Helioseismology."
Scientific American 253(3):48-57, 1985.
- Global Oscillation
Network Group (GONG)
Support for this work was provided by NASA through grant number
ED-90020.01-94A from the Space Telescope Science Institute, which is
operated by the Association of Universities for Research in Astronomy,
Incorporated, under NASA contract NAS5-26555.