The TRAPPIST-1 Chord

In February, 2017, astronomers announced that the nearby star TRAPPIST-1 has seven Earth-like planets. The orbital periods of the six innermost planets have nearly integer ratios. When periods are related by integer ratios, then the corresponding frequencies are related by integer ratios, too. The orbital frequencies of the six innermost Earth-like planets of TRAPPIST-1 have nearly integer ratios of 3:4:6:9:15:24.

Integer ratios remind me of musical chords. For example, the frequencies of a major chord’s notes are related by the ratios 4:5:6. While I know what a major chord sounds like, I didn’t know what a “TRAPPIST-1 chord” sounded like—until I edited a bit of JavaScript. The link below takes you to a page that lets you play the “TRAPPIST-1 Chord” where the frequency of each musical note in cycles per second is three times the frequency of the corresponding planet’s orbit in orbits per Earth year.

Go to page that lets you play the TRAPPIST-1 Chord

Thanks to JavaScript wizard Stoyan Stefanov for a post about generating audio in JavaScript. I’ve shamelessly stolen much of his code for the chord-playing page.

Here’s the NASA/JPL announcement:

Thumbnail image credit: NASA/JPL-Caltech.