Exoplanets with measured projected obliquity λ (upper panels) and true obliquity ψ (lower panels) as a function of their orbital period. The left panels show systems with a single detected planet, while the right panels show planets in multi-planet systems. The colour map indicates orbital eccentricity, with darker shades representing higher eccentricities. For planets in multi-planet systems, squares indicate those near a MMR. A system is considered near MMR if the orbital period ratios of adjacent planets are close to small integer ratios (e.g. 2:1, 3:2), based on values reported in the literature for each system. These criteria are derived from the period data and resonance assessments in the respective discovery or follow-up studies. The data are from the TEPCat catalogue (Southworth 2011), accessed on 26 February 2025.