希望の戦士

science:

This is the sound of the aurora on Saturn. Pretty eerie, no?

There is no sound in space. Outside planets and stars, molecules are spread out too thin for sound to propagate. It follows, then, that we can’t really hear sounds planets emit into space. But radio waves—electromagnetic waves with wavelengths longer than infrared light—are, as we know, handy for representing sound. And so it makes sense for us to interpret radio waves, whether originally encoding sound or not, as sound. These are radio waves emitted in conjunction with auroras around Saturn’s poles, similar to the northern and southern lights on Earth. They were picked up by the Cassini spacecraft and then interpreted as sound. But the sound was not in the audible range, so it has been downshifted by a factor of 44. And finally, so as not to bore us to death, it has been speeded up by a factor of 22. Realize, then, that many human choices were made in order for us to be able to “listen to space.” But if you can accept that, you can enjoy this.