Meet the Expert: Dr. Ryan MacDonald, theoretical physicist   Dr. Ryan MacDonald is a theoretical astrophysicist researching exoplanet atmospheres at Cornell University’s Carl Sagan Institute. He develops techniques to characterize the atmospheres of these distant worlds using ground and space-based telescopes. Dr. MacDonald is currently working on modeling exoplanet atmospheres in preparation for the launch… Continue Reading Episode 69: Where are the Aliens?