This week, we chat about some of our favorite stories—eating rats in the Neolithic, growing evidence for a gargantuan 9th planet in our solar system, and how to keep just the good parts of a hookworm infection—with Science’s Online News Editor David Grimm. Plus, Alexa Billow talks to the Massachusetts Institute of Technology’s Maria Zuber about NASA’s GRAIL spacecraft, which makes incredibly precise measurements of the moon’s gravity. This week’s guest used GRAIL data to explore a giant impact crater and learn more about the effects of giant impacts on the moon and Earth.   Listen to previous podcasts.   [Image: Ernest Wright, NASA/GSFC Scientific Visualization Studio; Music: Jeffrey Cook]