This week Skepticality celebrates it's long awaited 100th episode with a look back at past shows, thoughts about future installments and well wishes from their friends the skeptic community including Dr. Phil Plait (the Bad Astronomer), George Hrab (The Geologic Podcast) and Brian Dunning (The Skeptologists).

Why do we think aliens are out there? Is Earth really being visited? Will aliens really be short, gray, and hairless? What happens if we pick up a signal from another world?  These are just a few of the questions this week's guest tackles regularly, in his role as the senior astronomer for the SETI (Search for Extra-Terrestrial Intelligence) Institute. Dr. Seth Shostak talks with Swoopy about the ongoing search for life in the universe, as chronicled in his new book Confessions of an Alien Hunter: A Scientist's Search for Extraterrestrial Intelligence.