Progress in understanding of atmospheric evolution on terrestrial planets and explosive development of exoplanetary science, suggest to reassess and generalize our knowledge from the Solar system to multiple worlds beyond. Analysing the atmosphere of an exoplanet is the only possible means to assess its habitability, because so far we have no other access to biosignatures, for instance at the surface. The goal of the present Workshop is to bring together planetologists, experts on aeronomy and escape, climatologists, and astronomers to look for commonalities among atmospheres of the Solar system, the only example we know reasonably well, and the atmospheres of planets around distant stars, which can be assessed only indirectly. The WS will summarise our knowledge of the atmospheres and their evolution, based on ground/space-based observations and modelling, and will address future space missions to characterize exoplanets’ atmospheres and possibly find signatures of life there.

Several space missions have recently brought new insights about the atmospheres of the Solar system planets, such as Venus Express and Akatsuki on Venus, dedicated escape and atmosphere missions on Mars, MAVEN and ExoMars TGO, New Horizons and JUNO on outer planets. The exoplanet missions, flying and planned (Kepler, TESS), explore the transit method with advanced spectroscopic capabilities for atmospheres. This means that for a long time the focus will remain on atmospheres characterisation.

During the Workshop we aim first to address the diversity of observed planets, draw analogies to the Solar system planets, and review how an exoplanetary atmosphere can be constrained by observations. In the second part of the Workshop, the variety of processes bringing an atmosphere from its formation to known end members will be addressed, including protoatmospheres, early evolution, geochemical cycles, and escape. Present-day processes in the atmospheres of Solar system (chemistry, circulation) and current understanding of the atmospheres at the planets on other stars, including special cases, will be discussed. The Workshop will conclude with future space missions, which are important for understanding of exoplanetary atmospheres.