Music of the Spheres

10/29/06 – 11/4/06
C. Zaitz

It’s noisy out there in the solar system. The Moon is ringing like a giant basalt bell. Meteors and asteroids (and human-made spaceships) striking our cosmic companion cause its rigid mass to jiggle in waves that could be translated into sound, and if there was some air or other medium to bring those sound waves to our ears, we could hear the Moon ringing.

The Sun is also making noise, though from a very different cause. The end result is the same; both objects are oscillating in such a way that if we could hear the waves at those frequencies, we would hear them both “humming” like the high voltage lines that supply our homes with electricity. There are several websites that house the sounds of the sun as audio files. If you like watching snowy channels on TV, maybe you’d be interested in hearing the sun. Otherwise, I think it may be more interesting to note that if you were standing near the sun, you wouldn’t hear a thing. You’d also be vaporized.

Sound comes to our ear drums in pressure waves, transmitted through the air around us. Think of holding a slinky between your hands on a table, pushing your right hand toward and away from your left. You’ve made a wave formed by compressing and stretching the slinky, which is how a sound wave moves. Light waves are more like the sinusoidal wave you can make with the slinky if you move your right hand toward and away from your body. It’s a snake-like wave with crests and valleys. Light can travel through a vacuum like space, because it propagates itself. But sound needs a medium. That’s why we often say that there is no sound in space, because there is no air to transmit the sound waves.

However, that doesn’t mean that crafty humans can’t devise ways to “hear” all the energy waves in space. In fact, we are so clever at adapting information to our senses that we have been able to “see” and “hear” phenomenon like the ringing of the moon or the boiling of the sun. We play with the electromagnetic spectrum to see the universe in wavelengths beyond even what a snake or butterfly can see, and we stretch or compress the frequencies of space to hear beyond the range of even the perkiest Border Collie.

It’s true that the sound of the sun isn’t as exciting as Beethoven’s 9th, but we still get a lot of valuable information about the sun’s interior by watching and hearing it jiggle and vibrate. There’s a lot about the sun that we need to understand, so we keep our “ears on” when it comes to the sun. We also listen to empty space for any sign of non-natural activity, but so far, no alien top 40 lists have been heard in the frequencies we’re tuned into.

While you are listening to the sounds of space, don’t forget to look for comet Swan in the evening sky after sunset. Look to the west. If you see a bright star with a bit of an orange-y hue, you have spotted Arcturus. Look up from there for a little fuzzy spot. It’s possible you may see it even without a telescope or binoculars, but it’s always better to have a little optical help.

Until next week, my friends, enjoy the view!

Solar sounds can be heard at: http://solarcenter.stanford.edu/about/
Sounds of space: http://www.esa.int/esaSC/SEMLAJWO4HD_index_0.html