Dr Joanna Barstow

Satellite images of the planets in our Solar System reveal dynamic, changing worlds. Jupiter's poles are now known to be unexpectedly blue, contrasting with the equator, and the great red spot is gradually shrinking. Recently, we have also started to find out more about planets orbiting other stars - exoplanets. Studying exoplanets is exciting because it provides context for the evolution of Solar System planets, but also involves several challenges. Only rarely can we directly observe an exoplanet, because stars are so much larger and brighter. Instead, we measure the dip in the amount of light coming from the parent star when the planet passes in front. Gases and cloud particles absorb and scatter particular colours - or wavelengths - of light, so by measuring precisely the amount of light blocked by the planet at each wavelength, we can identify the unique fingerprints of substances in the planet's atmosphere - all without seeing the planet! However, there's a catch: we only get a single measurement averaged over the whole of the planet's visible atmosphere, which is not uniform and changes with time. To truly compare exoplanets with Solar System worlds, we need to understand what this average measurement actually represents. I aim to investigate, using computational models of light passing through an atmosphere, how a 3D, time-varying, cloudy exoplanet atmosphere can best be studied using these measurements. I will compare models with data from the new James Webb Space Telescope, due to be launched in 2021, which is set to provide the most detailed and precise observations of exoplanets yet.