Pythagoras fancied that there must be simple ratios for the distances between the heavenly bodies and the Central Fire, and that the motion of these bodies would therefore cause harmonious sounds, just as octaves and fifths and fourths arise from lengths of string with ratios of 1 to 2 and 2 to 3 and 3 to 4. There were two answers to the question why no one ever heard this Music of the Spheres. Aristotle (_De Cælo_, II. 9) makes the Pythagoreans say that we all hear it from the moment we are born, only we never notice it, as it is always going on. (If so, they must have thought it was a chord and not a tune.) The other answer, Aristotle’s own, was that there was not anything to hear.
There are many versions of the Music of the Spheres; but judging by what Ptolemy says (_Harmonica_, III. 16, and _Excerpta Neapolitana_, 2, 24) I think Pythagoras put the Firmament at 36, Saturn at 32, Jupiter at 24, Mars at 21⅓, the Sun at 18, Venus at 16, Mercury at 12, the Moon at 9, the Earth at 8, and (probably) the Antichthon at 6, with the Central Fire at 0. Thus, if the Firmament gave forth the sound of _f_, the Sun gave _f_ an octave higher up and the Moon gave _f_ an octave higher still. Saturn, Venus and the Earth gave _g_ in these three octaves, and Jupiter, Mercury and the Antichthon gave _c_ in these three octaves also, while Mars gave _d_ in the lowest octave by itself. And if that is what these orbs are ‘quiring to the young-eyed cherubins,’ I do not much regret ‘this muddy vesture of decay’ that hinders me from hearing it.
If the heavenly bodies went round in circles, their notes would never vary, as the distances would always be the same; but if they go round in ellipses, their notes will rise and fall with every variation in the distances. And as soon as Kepler had discovered that the Earth and other planets make ellipses round the Sun, he set to work to ascertain how far their notes run up and down the scale; and he published his results in 1619 in his _Harmonice Mundi_, V. 4-9. According to this, Saturn’s note went up and down a major third, and Jupiter’s went up and down a minor third; and Jupiter’s note at its lowest was an octave above Saturn’s at its highest. Similarly, the rise and fall was a fifth for Mars, a semitone for the Earth, and practically nothing for Venus, as its ellipse is nearly circular, whereas the long ellipse of Mercury produced a rise and fall of an octave plus a minor third; and between these rising and falling notes there were clear intervals of a major sixth from Mercury to Venus, a minor sixth from Venus to the Earth, a fifth from the Earth to Mars, and two octaves plus a minor third from Mars to Jupiter. And of course the trebles played their scales much faster than the basses, as they go round the Sun in much less time.