Who you gonna call (if aliens call first)?

What do we do if aliens reach out? Since 1989 scientists have maintained a set of protocols that would guide the world upon the discovery of signs of extraterrestrial intelligence coming from space. This year the protocols were updated, to account for the rapid change in technology and the rise of social media. Guest: Professor Michael Garrett, the Sir Bernard Lovell Chair of Astrophysics at Manchester University and Chair of the Search for Extraterrestrial Intelligence (SETI) Committee.