The visible–near-infrared spectrum of the dark spot that appeared on Neptune in 2018 indicates the presence of material that makes the aerosol layer at 5 bar darker at visible wavelengths. Such material can come from deeper layers via upwelling or by sublimation of H2S ice that reveals the darker condensation nuclei.
- Patrick G. J. Irwin
- Jack Dobinson
- Statia L. Cook
