About The Singing Orrery
A musical solar system: planets circle a sun and chime as they cross the line above it.
Kepler's music of the planets
In 1619 Johannes Kepler published Harmonices Mundi (The Harmony of the World), a book about the music of the planets, in which he gave each planet a voice. The same book holds what's now called his third law, which ties how long a planet takes to circle the sun to how far away it is: inner planets circle faster. The Singing Orrery is a small toy in that spirit.
Why every sky loops
Every ring's orbit divides one 12-second loop evenly: from the innermost ring out, planets go round 8, 6, 4, 3, 2 and 1 times per loop. Whatever you build, the whole sky comes back to where it started every 12 seconds, so every sky is a seamless song. Astronomers call whole-number rhythms like these orbital resonances.
Real skies have them too. Jupiter's moons Io, Europa and Ganymede keep a 1 : 2 : 4 rhythm, and TRAPPIST-1, a star about 40 light-years away, has seven planets locked in a chain of them.
Why nothing sounds wrong
Each ring has one note, and the notes come from a pentatonic scale: five notes that sound good together in any combination. (The black keys of a piano make one.) Inner rings sing higher.
A new sky every day
Today's Sky gives everyone the same sky each day. You hear its song with its planets hidden, rebuild it, and get Wordle-style marks on each planet. How it works .