Characteristics of Pluto’s haze and surface from an analytic radiative transfer model

Observations of Pluto from New Horizons have been combined with previous ground-based observations and fit to a radiative transfer model to derive the physical properties of the dwarf planet’s surface and atmosphere. We derive the macroscopic roughness, single scattering albedo, and directional scattering properties of the surface, and the single scattering albedo, optical depth, and single scattering phase function of Pluto’s haze. The haze particles are small, and some constraints can be put on their size. We find that Pluto’s haze is similar to that of Titan, rich in organic compounds, and unlike that of Triton. With organic compounds and a likely subsurface water ocean, Pluto may harbor sustainable habitable environments. Our model, which includes the coherent backscatter effect, fits the anomalously large opposition surge recently discovered on Pluto (Buratti et al. 2019b).