Exploring Exo-Venuses with JWST

Over the last decade, we have started to uncover details of exoplanet atmospheres using the technique of transmission spectroscopy. When the planet crosses in front of its parent star during orbit, some of the starlight is filtered through the atmosphere, emerging with a fingerprint of any absorbing gases and aerosols that are present. Currently, we are most

capable of doing this for hot, gas giant planets with hydrogen-helium atmospheres, and smaller, cooler planets present a challenge. Venus is the planet in the Solar System with the greatest similarity to Earth in terms of its size and mass, yet its evolutionary history has culminated in an incredibly hot, acidic and

inhospitable world. Studying Venus-like planets around other stars will help us to understand how this might have happened.