Now, these sounds are fun to listen to and we can imagine that they will show up in space movies, but these sounds are not the only thing that deep space instruments record or what scientists use to do their work. The following picture displays some numbers shown as a graph. To learn the secrets of the planets, we have to make conclusions about the lines on these graphs.

This is a graph of signals recorded at Siple Station, Antarctica. It is from a scientific paper and it represents the type of data that scientists use to figure out what happens in space.

Let's try to pick out some features in the this graph that match what is known about whistlers. The vertical axis represents frequency or pitch. The horizontal axis represents time. The measurement is wave amplitude or how loud the sound is at that pitch. Notice that the lines are dark at the top and bottom of the graph. That means there seem to be constant signals at low and high frequencies. This is the constant static heard in the sounds.

Whistlers are constant-loudness signals (the constant-loudness is difficult to pick out here ... it is the darkness of black dots for any single trace. There are many overlapping signals here). The frequency decreases through the complete hearing scale and ends with the lowest tones you can hear. The whole process lasts almost a full second. You can compare a whistler to plucking a guitar string. The pluck is like the lightning that disturbs the magnetosphere. That disturbance runs through the entire magnetosphere and some parts pick up certain frequencies and make them louder. Like the guitar string whose length, tension and weight pick up a certain note or tone, the plasma in the magnetosphere picks up frequencies and "sings" back to us this whistling sound. In a real way, the magnetosphere is communicating its structure through these radio signals. The density, shape and other parts of the structure are waiting for a "pluck" to excite them so they can "sing" back to us over our radios.

Notice the down-swept curves between :28 and :30 and around :44 on the time axis. These curves represent the whistle sounds when the sound goes from high pitch to low pitch. The other sounds in this page also have graphical representation.