The Music of the Spheres

It is popularly known, predominantly courtesy of Holst’s The Planets, that people throughout the course of human civilisation have assigned musical patterns and harmonies to the movements of the stars and planets. This “musica universalis” sees early use in Hebrew mythology, which explains the cosmos as having movements and harmonies that are designed to sing the praises of the creator-deity. In that mysticism, there is an intriguing emphasis upon the interrelatedness of many aspects of the universe, including language, mathematics, music, astrology and the demiurge.

This search for such relationships is not, of course, unique to the Jewish people, as can be easily determined from my earlier blogs – constellations and the ‘study’ of astrology are, if anything, elegant proof of this desire. Of particular interest, however, is the fact that there is actually some validity in this particular belief.

Johannes Kepler, who gave us the laws of planetary motion, was a firm believer in a divinely-designed resonance between the planets, and used his observations and calculations to seek it out. Kepler’s great gift to astronomy was the realisation that planets orbit elliptically, rather than circularly, creating what are called the perihelion (greatest distance from the orbital centre) and the aphelion (shortest distance from the orbital centre). The variation in distance also, however, results in changes in a planet’s angular velocity, as it speeds up while closer to the orbital centre.

In his Harmonices Mundi (The Harmony of the World), he observed that the ratio between a planet’s least and greatest angular velocity relates to a musical harmony. Kepler found that maximum and minimum velocities of Saturn formed an almost perfect ratio of 4:5 (a major third in music). The motions of Jupiter differ by a 5:6 ratio (a minor third). Mars differs 2:3 (a “diapente”); Earth differs 15:16 (a semitone); and Venus differs 24:25 (a “diesis”, which is, intriguingly, the smallest difference considered generally audible to the human ear).

Kepler also discovered that nearly all of the ratios of the maximum and minimum angular velocities of neighbouring planets produce musical harmonies. The orbits of Mars and Jupiter represent the single exception, being a less flattering (or disharmonic) 18:19 ratio – in his defence, however, this dissonance could be explained by the presence of the main asteroid belt, which was not discovered for a further 150 years. Had a visible planet orbited there, it is feasible to believe that this pattern of harmonies could well have continued.