Mass ratio of resonant exoplanets and some solar system satellite pairs. Only well-characterized systems (Wright et al. 2011) are listed. The size of each bubble is indicative of the orbital distance of the inner orbit in units of the central body radii. Systems depicted by blue circles are those with a more massive inner object. Systems represented with green circles are those with a more massive outer object. This figure clearly shows that the restricted formalism of the three-body problem is inapplicable in numerous settings of astrophysical interst.