On Feb. 22 2017, astronomers announced the discovery that 7 Earth-sized planets orbit a nearby red dwarf star known as TRAPPIST-1, (Gillon et al 2017, Luger et al 2017). At least two of them should have the right temperatures to host liquid water making them prime targets in the search for life beyond the solar system.

The planets of TRAPPIST-1 are locked in the longest known chain of resonances ever discovered, with each planet’s orbital period forming simple ratios with those of its neighbours. For every 2 orbits of the outermost planet, the next planet inward orbits 3 times, the next one 4, then 6, 9, 15 and 24 times. We have recently shown in a research paper that the planets can settle into this configuration while drifting in their birth disk, and this fine tuning is likely the main reason the system has managed to survive to the present day (Tamayo et al. 2017).

Since musical harmony and repeating rhythms are also a result of simple period ratios, the orbits of the TRAPPIST-1 planets can be translated into musical form. For each planet, we play one note per orbit using the pitches that result from bringing the planet’s frequencies into the human hearing range. We then add drums for every time a planet passes its neighbour to hear the rhythms of their repeated gravitational tugs. To add a little more flair, we converted the fluctuating brightness data of the star itself directly into sound. Continue reading to learn about the creation of each element of TRAPPIST Sounds or play TRAPPIST-1 for yourself!