Want To Create A Space Symphony? Wait For A Solar Storm

Feb 10, 2013
Originally published on February 10, 2013 4:58 pm

In 2001: A Space Odyssey, Stanley Kubrick evokes the immense and powerful nature of outer space with Richard Strauss' score, Thus Spoke Zarathustra.

The music is now inextricably linked to the idea of space exploration. But what if, instead, you could create music from solar eruptions?

That's exactly what sonification specialist Robert Alexander does.

Although you can't hear anything in space, scientists can still use sound to understand the solar system by turning data collected by NASA satellites into sounds and music.

Alexander, who works at the Solar and Heliospheric Research Group at the University of Michigan, spoke to Jacki Lyden, host of weekends on All Things Considered, about what's behind some of the solar music he has composed.

Listen to some of the sounds Alexander has created through a process called sonification.

"Solar Heartbeat" starts with raw audio data. Alexander's filter is then slowly applied, so the low frequency hum of the solar rotation is more audible.

Alexander describes some of the solar events that create the sounds we hear in his work:

"There are a lot of things like solar flares or coronal mass ejections, and these things have the potential to knock out satellites and disrupt the power grid. And, so, when we think of the sun as a very dynamic and turbulent system, when we listen to the unfiltered and the raw data, that's what we're hearing. We're hearing the raw turbulence of the sun."

While the clip above depicts the filtered and unfiltered sounds of the sun, Alexander also uses his work to compose music.

One of his compositions uses different voices to depict the charged states of carbon.

"The charged states of carbon tell us something about the temperature and the energy coming off the sun," Alexander says. " So, it really lends itself to sonification. ... We're always going to have a sort of natural sense of balance between these voices."

Another of his compositions reflects a significant moment in solar history, known as the Halloween Storms of 2003, which NASA described as "some of the most powerful solar storms ever recorded."

"There's this really large increase in this sort of wind sound that I've generated, and also a swelling in the voices," Alexander says, describing how he transformed the storms into music. "We also get this sense of expanse and ... when we get this huge swell in the data is [when] the velocity of the solar winds jumps up. And we have this huge variance in so many of these variables."

You can hear the dynamic changes of the sun in Alexander's music, including this symphony, which he composed with elements of solar data.

The high bell tones represent solar eruptions.

Alexander says he hopes that translating the sound of the sun into audio can help us understand and better relate to the solar system around us.

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As we learned in the movie "Alien," in space, no one can hear you scream. Of course, we can't hear anything because there is no atmosphere out there. But scientists can still use sound to understand the solar system a little better by turning masses of data collected by NASA satellites into sound and music. Robert Alexander is a sonification specialist with the Solar Heliospheric Research Group at the University of Michigan. Welcome.

ROBERT ALEXANDER: Hi. Thanks for having me.

LYDEN: Well, we're delighted to have you, and we're all wondering what a sonification specialist is.

ALEXANDER: So what I do is I take data, and I translate it into sound. I myself work mostly with solar wind data and data from satellites and explore these sounds in a new way.

LYDEN: And how do you convert that data into sound without getting into a blizzard of technical details?


ALEXANDER: Sure. To sonify data is essentially to take any given data parameter - so it could be, let's say, the speed of the solar wind - and I can then map that and create a sound, a whooshing sound like (makes whooshing sound) that represents the solar wind in some kind of way.

LYDEN: OK. Let's hear an example of what you do, Robert, and this is the heartbeat of the sun.


LYDEN: So that's pretty cool, kind of reminds me of listening to a heat ventilation shaft, but of course, it's the sun. What are we actually hearing right now?

ALEXANDER: So that's actually 40 years' worth of solar data - it's several hundred thousands of lines' worth of data. And what we're listening to - I've filtered out a lot of the high frequency content, so we're listening to this low hum. And that's created by the rotation of the sun, actually.


ALEXANDER: When you have something that's rotating like the sun every 27 days, over the course of 40 years, we end up with this underlying hum, essentially.

LYDEN: Hmm. Is there something about the sun that lends itself to sonification as opposed to any other planetary body or the moon?

ALEXANDER: The sun, it's a window into getting to know many other stars much more deeply. And we have so many satellites up. They're all streaming down masses of information. And, you know, we have so much of this solar data, and we're trying to find ways to quickly and effectively navigate it all. And sonification offers us a way to, you know, possibly begin to do that.

LYDEN: Now, it is, after all, a sound experiment, and you're getting scientific inquiries from it, but I understand you've also taken it a step further, just for yourself, and you've actually composed some music from these sounds. Let's just listen for a moment.


LYDEN: Well, Robert Alexander, what you've done is incredibly beautiful. I hope you can take this music maybe to, you know, a hall, and people can hear it somewhere.

ALEXANDER: Sonification does really lend itself to education and public outreach, because I think a lot of people, they see a glass, and they just kind of turn off. And I think sonification has the potential to really engage the curiosity of the listener and to relate to it on a human level, more of a visceral level.

LYDEN: Well, thanks for the fascinating conversation.

ALEXANDER: Thank you so much.

LYDEN: Robert Alexander is a sonification specialist with the Solar Heliospheric Research Group at the University of Michigan. He turns solar data into sound and music.


LYDEN: It's NPR News. Transcript provided by NPR, Copyright NPR.