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Background | Procedure | Follow-up | Related
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Materials
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Put out as many of the "sound creating objects" as you have for students to work with. Have them create a table with columns for "Object Name", "Object Description", and "Sound it Makes" to be filled out as they experiment with each object. Depending on how open ended you want to be with your students, you may wish to discuss the kinds of observations you want them to make and write down as they experiment. Younger students especially will benefit from some cues such as talking about the size of the object, or its density or length, as well as describing sound in terms of pitch and tone, rather than just loudness.
It is a good idea to give your students clear objectives - i.e. "Today we are going to explore the relationship between the sound an object makes and its physical characteristics."
After your students have had a chance to try out each of the objects lead a discussion with them about what they observed. You could make a chart on the board and fill it out as students give their answers and observations. You want to guide them to come up with the relationship that larger (longer, denser) objects tend to have lower pitches than smaller (shorter, less dense) objects.
Discussions of hollow versus solid sounds are also appropriate here.
The bottle harmonicas provide a good way to introduce a discussion about what is vibrating and creating the sound. Point out the difference in pitch when you blow across the mouth of the bottle (pitch increases with the amount of water in the bottle, the air is vibrating) versus when you strike the bottle (pitch decreases with the amount of water in the bottle, the water is vibrating).
Once the relationship has been discovered and stated by your students, relate it to helioseismology by showing the slide set or overheads. You can adapt the following script to help tell the story.
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 the sun.
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" say: I 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 move.
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.
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NOAO is operated by the Universities for Research in Astronomy (AURA), Inc. under cooperative agreement with the National Science Foundation. |
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