spaceSpace and Physics

How Scientists Listen to the Sun

2039 How Scientists Listen to the Sun
Erupting sun, September 18, 1997 / SOHO- EIT Consortium, ESA, NASA

There’s more to satellite data than meets the eye. Researchers have found a new way to listen to the sun’s magnetic field and pick out anomalous sounds that could portend trouble for our electronics on Earth. 

Researchers have been listening to space data for at least a few decades, but the technique isn’t used often because it requires a certain level of familiarity with the sounds. After all, what does typical solar wind turbulence even sound like, and how is it different from something atypical? “It’s about using your ear to pick out subtle differences,” says Robert Alexander of the University of Michigan. He trains heliophysicists at NASA’s Goddard Space Flight Center to pick out these differences by listening to instead of looking at data.


“NASA produces a vast amount of data from its satellites. Exploring such large quantities of data can be difficult,” Alexander explains in a news release. "Sonification offers a promising supplement to standard visual analysis techniques.” With sonification, data and measurements are displayed as sound. Imagine the beeping from a heart rate monitor that measures your pulse -- but with explosions indicating large events occurring on the sun. In some cases, listening helps process data more rapidly and in more detail. In 10 minutes of what might appear to be white noise, researchers can listen to a month’s worth of data.

NASA's Wind satellite, which orbits between Earth and the sun, is constantly observing the temperature, density, speed, and magnetic field of the solar wind rushing past. This constant stream of particles affects space weather, which can interfere with our Earthly technologies.

This clip below was gathered from the Wind satellite in November 2007 and contains a reverse shock. Listen for three distinct sections: a warble leading up to a short knock at slightly higher frequency, which is followed by a quieter segment of broadband noise. This occurs when a fast stream of super hot, charged gas (or plasma) is followed by a slower one, resulting in a shock wave that travels towards the sun.



Alexander and colleagues created a computer algorithm that converts electromagnetic frequencies into sound. Translating raw, unedited data from space satellites into audio is like collecting sound from a singer: The microphone detects changes in pressure, then converts the pressure signals to changes in magnetic intensity in the form of an electrical signal, which is stored on a reel tape. Magnetometers on the Wind satellite measure changes in the magnetic field, creating a similar kind of electrical signal. “If there is a frequency embedded in the data, then that frequency becomes audible as a sound,” Alexander says

In the example below, his team condensed three hours of real-time recording from the Wind satellite from November 2007 to a three-second audio clip. Listen for the distinct chirping at the beginning, followed by a percussive event, culminating in a loud boom.





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