Hear the Resonace of Trappist 1

Trappist 1 is a pretty cool planetary system:

  • Seven planets orbiting a red dwarf star
  • Three planets in the habitable zone where liquid water may be present.
  • All the planets are in tight orbits with periods ranging from 1.5 to 19 days.
  • The name was inspired from a type of beer brewed by monks.

The seven planets in orbit around the TRAPPIST-1 could fit inside the orbit of Mercury. Image Credit: NASA/JPL-Caltech

I didn’t realize that all seven planets in the Trappist 1 system are in resonance where their orbital periods are related by small integer ratios. For example, for every 2 orbits of the outermost planet, the next planet inward orbits 3 times. In our own solar system, Pluto and Neptune are also in a 2:3 resonance. The Trappist 1 system has a much longer resonance chain that involves all its planets. In fact it is the longest know chain of resonant exoplanets. For every 2 orbits of the outermost planet, the more inner ones complete 3, 4, 6, 9, 15, and 24 orbits respectively.

Initially, it seemed like the orbits of the Trappist 1 planets would not be stable with some planets being flung out of the system, colliding, or becoming moons of other planets in less than a 1/2 million years. A Canadian astronomer, Daniel Tamayo, is the lead author on a new paper in The Astrophysical Journal Letters that explains how this system could have formed and remained stable for over 50 million years – the maximum that they could simulate on their supercomputer – by accounting for the initial conditions when the planets formed and their subsequent drift into position.

Resonances are also key to music. Matt Russo is an astrophysics-colleague of Tamayo who is also a musician. He arbitrarily assigned the note C to the outermost planet and set notes for the other planets based on their relative orbital periods. You can listen to the Trappist 1 resonances in the video below.


Trappist 1 Planetary System Translated Into Music. Video Credit: SYSTEM Sounds

The SYSTEM Sound site also lets you make your own music using the TRAPPIST-1 planets as your instrument .