Visions of Harmony: Inspired by NASA’s Mission Juno
This Apple Music original celebrates the space agency’s groundbreaking journey to Jupiter—and the intersection between science and art.
While this is new harmony and space isn’t.
In 1619 Johannes Kepler publisahed Harmonices Mundi ( The Harmony of the World).
While medieval philosophers spoke metaphorically of the “music of the spheres”, Kepler discovered physical harmonies in planetary motion. He found that the difference between the maximum and minimum angular speeds of a planet in its orbit approximates a harmonic proportion. For instance, the maximum angular speed of the Earth as measured from the Sun varies by a semitone (a ratio of 16:15), from mi to fa, between aphelion and perihelion. Venus only varies by a tiny 25:24 interval (called a diesis in musical terms). Kepler explains the reason for the Earth’s small harmonic range:
The Earth sings Mi, Fa, Mi: you may infer even from the syllables that in this our home misery and famine hold sway.
The celestial choir Kepler formed was made up of a tenor (Mars), two bass (Saturn and Jupiter), a soprano (Mercury), and two altos (Venus and Earth). Mercury, with its large elliptical orbit, was determined to be able to produce the greatest number of notes, while Venus was found to be capable of only a single note because its orbit is nearly a circle.
At very rare intervals all of the planets would sing together in “perfect concord”: Kepler proposed that this may have happened only once in history, perhaps at the time of creation.
Kepler reminds us that harmonic order is only mimicked by man, but has origin in the alignment of the heavenly bodies:
Accordingly you won’t wonder any more that a very excellent order of sounds or pitches in a musical system or scale has been set up by men, since you see that they are doing nothing else in this business except to play the apes of God the Creator and to act out, as it were, a certain drama of the ordination of the celestial movements. (Harmonices Mundi, Book V).
Kepler discovers that all but one of the ratios of the maximum and minimum speeds of planets on neighboring orbits approximate musical harmonies within a margin of error of less than a diesis (a 25:24 interval). The orbits of Mars and Jupiter produce the one exception to this rule, creating the unharmonic ratio of 18:19. In fact, the cause of Kepler’s dissonance might be explained by the fact that the asteroid belt separates those two planetary orbits, as discovered in 1801, 150 years after Kepler’s death.