By: Amanda Thornton

The title of the song "Twinkle, Twinkle, Little Star," which is sung by schoolchildren across the country, may in fact be rooted in science. Stars called Cepheids, first discovered in 1784, have been studied by astronomers for years. Cepheids are stars that brighten and dim, changing their luminosity at regular, measurable intervals. Because of this, scientists can use Cepheids as "cosmic yardsticks" to measure huge distances in space.

To be classed as a Cepheid, a star must have certain explicit functions. The first is regularity, meaning its pattern of bright and dark periods does not change over time, and the second is uniformity, meaning there is a definite relation between the patterns of brightness and darkness, which, once the period of brightness is known, can be inferred. Because of this, astronomers can watch Cepheids and map the pattern of brightness and darkness, which helps them extract the stellar distance from Earth. Because Cepheids are so bright, we can even see the ones in galaxies besides our own. The farthest Cepheids from Earth have been found in the constellation Virgo, in a galaxy called M100. These stars twinkle an astronomical 56 million light-years away from Earth!

So the next time you sing the song "Twinkle, Twinkle, Little Star," remember that those glittering lights actually DO twinkle. Science proves it.