Airdate: Jan 16, 2004
Scientist: Craig DeForest
Sounds of the Sun - Inside
Scientists are using sound to answer one of mankind’s oldest questions - what might be taking place inside the sun?
ambience: Solar vibrations
Since the dawn of time, mankind has wondered about what kind of activity might be taking place inside the sun. Well, today scientists are using sound to help answer that question. I'm Jim Metzner, and this is the Pulse of the Planet.
“The Sun is constantly oscillating at about a million different notes like a, a giant gong that's been struck or like a wine glass that you're rubbing your finger on, except with a much more complicated sound.”
Craig DeForest is a solar physicist with Stanford University. He's part of the NASA team that's using a spacecraft known as SOHO, to monitor sound waves on the surface of the sun. SOHO stands for the Solar and Heliospheric Observatory.
“Now we can't hear that sound on Earth for two reasons. One is that sound doesn't travel through the vacuum of space. The other reason is that the larger an object is, the deeper the sounds that come out of it. Well, the Sun is enormous compared to the Earth. It's about a million times larger than the Earth, so the sounds that come out of it are correspondingly deep.”
How deep? Well, in order for us to actually listen to the oscillations of the sun, we've had to speed them up 42,000 times. And it's not just one sound that instruments have detected; it's many. The result of a solar interior that's in constant motion. In this recording, from at least one million vibrations, we've filtered out all but around a dozen sounds.
"The Sun is very complex. It's an incredible cacophony -- If you can imagine a million different orchestra players all playing different notes at the same time. By comparing how the different sound waves interfere with each other and the subtle frequency shifts between different types of sound waves, we can determine the structures through which the sound waves pass on their journey through the Sun."
Pulse of the Planet is presented by the National Science Foundation. I'm Jim Metzner.