Guest Benjamin Greenhagen, a planetary scientist at Johns Hopkins University’s Applied Physics Laboratory in Maryland, outlines the lunar surface’s remaining mysteries --- everything from permanently shaded regions at the North and South poles to near and far side impact craters. Greenhagen is the deputy principal investigator of the Diviner Lunar Radiometer instrument onboard NASA’s Lunar Reconnaissance Orbiter (LRO) and is an expert on the geology of the Moon’s surface.

Guest Paul Davies, a theoretical physicist and director of the BEYOND Center at Arizona State University, gives an enlightening and fascinating interview on the true nature of the Cosmos and why there is something rather than nothing. We also discuss his new book: “What’s Eating the Universe? --- and Other Cosmic Questions.”

Guest Christopher Combs, an assistant professor of aerodynamics at the University of Texas at San Antonio, discusses current prospects for supersonic. hypersonic and even suborbital spaceplane passenger flight. Combs clearly communicates the technical aspects of flight faster than sound and the issues that are hindering our ability to hop from one corner the Earth to the other within 90 minutes or less.

Acclaimed U.K. journalist Mark Piesing chats about his first book N-4 DOWN: THE HUNT FOR THE ARCTIC AIRSHIP ITALIA (Harper-Collins) which tracks the long-forgotten history of how airship and early aviators tried to conquer the North Pole. Umberto Nobile’s Italia airship crashed onto the Arctic ice in May 1928 and sparked an international search before Nobile and what was left of his crew were eventually saved by the then relatively novel technology of radio.

Guest Sheryl L. Bishop, a social psychologist and professor emeritus at the University of Texas Medical Branch at Galveston gets real about what we need to make happen if astronauts are going to be able to thrive off-world beyond low-Earth orbit. Bishop chats candidly about her new book “Space Habitats and Habitability: Designing for Isolated and Confined Environments on Earth and in Space,” co-authored with Sandra Hauplik-Meusburger.

Guest Edwin (Ted) Bergin, professor of astronomy and Chair of the Dept. of Astronomy at the University of Michigan in Ann Arbor, discusses whether our existence in this solar system is directly related to the initial chemical makeup of our star’s protosolar disk from which our planets formed.

University of Chicago associate professor Dorian Abbot chats about his research on the controversial Snowball Earth Hypothesis. That is, the idea that at least twice in Earth’s geological past, our planet was basically a glacial ball of ice and snow. Abbot says it likely happened some 2 billion years ago and again some 600 to 800 million years ago. There's evidence for at least four such snowball events that likely persisted for tens of millions of years.

Our civilization and technology as we know it owes itself to a fluke of evolution that enabled the development of human intelligence. It’s a marvelous and nuanced intelligence that cannot be replicated anywhere else in the cosmos. That doesn’t mean that intelligent life isn’t out there. But it’s likely not very similar to our own. Guest Bret Stetka chats about his new book “A History of the Human Brain” from Workman Publishing and tackles some of humanity’s biggest questions.