Watching Supernovae with H2O

In the good old days you needed a lens or a mirror to have a telescope, but now they'll use any old thing to look at the sky: ultra-precise orthogonal laser interferometers to measure gravitational waves or big tanks of water to see gamma rays from supernovae (that's Latin for supernovas). Jim Cooney and Zoe Landsman join Josh and Addie to talk about a new gamma ray observatory and why anyone might build such a thing. Also, planets and stuff.