Kepler’s score

In Book Five of Harmonices Mundi, printed in Linz in 1619, Johannes Kepler wrote down the music he believed the planets make. He wasn’t listening for sound. He measured how fast each planet appears to sweep across the sky as seen from the Sun, at its slowest, farthest point and at its fastest, closest one. The ratio between those two speeds is a musical interval, and the slide from one to the other is the planet’s song.

Working through these numbers, he also found the rule now known as his third law: the square of a planet’s year grows with the cube of its distance from the Sun. It sits in the same book as the songs.

The choir

Kepler gave the planets voices by range. Saturn and Jupiter sing bass, Mars tenor, Earth and Venus alto, and Mercury soprano. He wondered whether all six had sounded in perfect agreement only once, perhaps at the moment of creation.

Soprano: Mercury
Alto: Venus, Earth
Tenor: Mars
Bass: Jupiter, Saturn

Six songs

Each staff is our engraving of the interval Kepler gave the planet, rising from its slowest point to its fastest and back. Press play to hear one orbit sung at his exact ratio.

One pairing never fit his scheme: the step between Mars and Jupiter, where the asteroid belt lies, unknown in his day. Uranus and Neptune were found long after Kepler, so they have no part in his score, but in this sky they sing by the same law.

Maya Labs Playground

Music of the Spheres

Johannes Kepler noticed that every planet speeds up near the Sun and slows as it swings away, and in 1619 he wrote that change down as music. Here the planets start where they are today and move by his laws. Each world hums a note that bends with its speed, and rings as it crosses a line.

Sound on. Headphones help.

Music of the Spheres

How the sky sings

Things to try

Keys