The ancients believed in the "music of the spheres"—that the planets and stars moved through the heavens in harmonic ratios. Today's astronomers are also "listening" to the stars, using the powerful Kepler telescope to measure their internal vibrations, a technique they call "astroseismology." So far, 500 stars have been mapped this way, with astronomers measuring tiny fluctuations in their light to listen to sound waves inside them, reports the BBC.
Kepler was actually designed to measure light fluctuations from distant stars in the search for other planets. But to do so, Kepler measures light levels so precisely it can also reveal soundwaves bouncing within those stars. "Using the resonances, we can literally build up a picture of what the inside of a star looks like—there's no other way of doing that," said one astronomer. "It's not easy to do, but we're now getting there, thanks to Kepler."