Jupiter as an exoplanet: UV to NIR transmission spectrum reveals hazes, a Na layer and possibly stratospheric H2O-ice clouds

TL;DR

This study uses a novel observational method during a solar eclipse to analyze Jupiter's atmosphere, revealing hazes, a sodium layer, and possible water-ice clouds, providing insights applicable to exoplanet atmospheres.

Contribution

It introduces a new technique for studying giant planet atmospheres by observing a satellite during a solar eclipse, revealing atmospheric components relevant to exoplanet research.

Findings

Detection of atmospheric hazes and clouds in Jupiter's spectrum.

Identification of sodium absorption features.

Evidence for stratospheric water-ice clouds.

Abstract

Currently, the analysis of transmission spectra is the most successful technique to probe the chemical composition of exoplanet atmospheres. But the accuracy of these measurements is constrained by observational limitations and the diversity of possible atmospheric compositions. Here we show the UV-VIS-IR transmission spectrum of Jupiter, as if it were a transiting exoplanet, obtained by observing one of its satellites, Ganymede, while passing through Jupiter's shadow i.e., during a solar eclipse from Ganymede. The spectrum shows strong extinction due to the presence of clouds (aerosols) and haze in the atmosphere, and strong absorption features from CH4. More interestingly, the comparison with radiative transfer models reveals a spectral signature, which we attribute here to a Jupiter stratospheric layer of crystalline H2O ice. The atomic transitions of Na are also present. These results are relevant for the modeling and interpretation of giant transiting exoplanets. They also open a new technique to explore the atmospheric composition of the upper layers of Jupiter's atmosphere.