Exocast-4 b In the fourth exocast episode: Hannah take us on a whirlwind tour of the planets in our own familiar solar system. Andrew covers how we can use the Mass and Radius of exoplanet to tell us about their interiors. Hugh looks at the news including observations of Trappist-1 b & c, and 136 new planets. And Andrew adopts the Earth-like planet Kepler-186 f to our growing family.