How do planets form out of dust particles? And what does that have to do with fluid dynamics? To find out, Dr. Charles Liu and co-host Allen Liu welcome astrophysicist Dr. Holly Capelo from the University of Bern in Switzerland. As always, though, we start off with the day’s joyfully cool cosmic thing, which takes us to the Observatory of Paris, where a group of scientists are delving into the formation of planetesimals. What are they, where do they come from, and when do they form? Holly dives right in to explain what we know about them, and what forces might prevent planetesimals from growing into planets. Along the way, she blows Chuck’s mind about planet formation and accretion disks. Next, Dr. Capelo uses Alice in Wonderland to help describe her extensive experiments flying on Novespace’s Air Zero-G (the European equivalent of NASA’s “Vomit Comet”) flying in parabolas in order to better understand fluid dynamics, aerodynamic drag and the impact of freefall, microgravity and hypergravity on dust particles. For our first question this episode, Allen asks Holly about what makes up interplanetary debris, now and in the past. You’ll learn all about ice lines, the impact of vacuum on water vapor and dust particles, minimum mass solar nebulas, density distributions and how much debris there actually is floating around our solar system. You’ll also hear a little bit about Holly’s other experiences, as a dancer, and how grad school made it harder to stay in shape. Our next question revolves around the possible atmospheres of the Moon, comets and planetesimals. Holly explains how we have evidence of transitory events, like outgassing. She also tells us about an upcoming “comet interceptor” mission to study comets that will place a satellite at a Lagrange point to wait for a comet to enter our solar system and then fly to meet it. If you’d like to know more about Holly and her experiments, you can follow her on Twitter @hollycapelo. We hope you enjoy this episode of The LIUniverse, and, if you do, please support us on Patreon. Credits for Images Used in this Episode: Accretion disks imaged by ALMA – European Southern Observatory, CC BY 4.0 Phase diagram of water – Hokanomono & Cmglee on Wikimedia, CC BY-SA 3.0 Novespace’s Air Zero-G aircraft – Marc Lacoste, CC BY-SA 4.0 Illustration of Rosetta at comet 67P – Deutsches Zentrum für Luft- und Raumfahrt, CC-BY 3.0
