Characterizing atmospheres of transiting planets from the ground Ignas Snellen (Leiden Observatory, The Netherlands,

Abstract: The cancellations of both the Terrestrial Planet Finder and Darwin missions mean that it is unlikely that a dedicated space telescope to search for biomarker gases will be launched in the next 25 years. In this talk I will advocate that ground-based telescopes provide a strong alternative for finding biomarkers in exoplanet atmospheres through high-resolution transit observations. I will review some of the exciting result that have recently been obtained on hot-Jupiter atmospheres, and will discuss what can be expected from the future ELTs. This includes the orbital inclination and masses of hundred(s) of non-transiting planets, line-by-line molecular band spectra, planet rotation and global wind patterns, longitudinal spectral variations, and possibly isotopologue ratios. Ultimately, if habitable Earth-like planets transiting late M-dwarfs are common, detection of molecular oxygen may be within reach.