Ratio between the mass of a planet or moon and that of its host as a function of orbital period. We represent the known population of exoplanets (from exoplanet.eu, Schneider et al. 2011) from three different detection methods. The Solar system is also highlighted. The TRAPPIST-1 system, like the Galilean moons of Jupiter, share a similar parameter space with the sub-Neptune and super-Earth population. Orbital periods are used to reveal the various sub-populations.