Dr. Alexandria Johnson

Postdoctoral Associate

Alexandria Johnson is a postdoctoral associate in the Cziczo Group (Earth, Atmospheric and Planetary Science), MIT. Her original field of study was Earth’s atmosphere, but she has expanded her work to the investigation of exoplanet atmospheres. Alexandria Johnson, Ph.D.,Postdoctoral Associate, Cziczo Lab, Earth, Atmospheric and Planetary Sciences, MIT The identification and characterization of extra solar planets, or exoplanets, has given context to Earth and the potential for analogs orbiting other stars. However, one long-standing question remains – Can these planets sustain life as we know it? A first step in the search for life beyond our solar system is the detection of biosignature gases; known to be produced when Earth based life metabolizes. Yet a fundamental uncertainty remains in just how easily these gases can be detected through constituents in exoplanet atmospheres such as aerosols and clouds. As a Simons Foundation postdoctoral fellow working at MIT I am using laboratory based experiments to determine how exoplanet aerosol and cloud particles interact with light across the visible spectrum. In particular how they scatter and polarize light under a wide range of conditions. The aim of this project is three fold. First, to better understand the role and properties of aerosols and clouds in exoplanet atmospheres. Second, to determine how clouds of various compositions and morphologies limit our ability to detect biosignature gases. Third, to investigate any properties of scattered and polarized light we may be able to take advantage of for determining the overall composition of cloudy exoplanets.