A New Era of Three-Dimensional Maps of Exoplanet Atmospheres

Eclipse mapping is a technique used in astronomy to spatially resolve the emitting surface of one object by carefully measuring the loss of light as another object passes in front of it, blocking successive regions from view. Having previously been applied to map stellar surfaces, Pluto, and disks of gas accreting onto stars, in 2012 this technique was first used to create a two-dimensional map of an exoplanet (in this case, a large gas giant planet, orbiting a nearby star). That measurement was only possible through repeated Spitzer Space Telescope observations of one of the brightest known exoplanet systems, just at the edge of our measurement capabilities. For the last ten years, this has been the single exoplanet eclipse map in existence ... until now. With the recently launched JWST mission, we now have the capability to map the atmospheres of more exoplanets and in better detail. Since these measurements are spectroscopic we can use the fact that different wavelengths of light emerge from different depths in the atmosphere to access fully three-dimensional information about the planets' atmospheric structure, providing exquisite constraints on our models. However, the retrieval of this information from these new data is far from trivial. In this talk I will explain the technique of exoplanet eclipse mapping, discuss some of the nuances involved, and perhaps show the first exoplanet eclipse map from JWST.