Speaker: Bill Bottke from Southwest Research Institute

Title: "Exploring the Echs of Giant Planet Migration -- Lost Neptunes and Early Bombardment"

Abstract: Heavily cratered surfaces on the Moon, Mars, and Mercury show the terrestrial planets were battered by an intense bombardment during their first billion years or more, but the timing, sources, and dynamical implications of these impacts are controversial. Dynamical models that include populations residual from primary accretion and destabilized by giant planet migration can potentially account for observations. For the latter, giant planet instability models can now successfully reproduce the orbits of the giant planets, the origin/properties of Jupiter/Neptune Trojans, irregular satellites, the structure of the main asteroid and Kuiper belts, and the presence of comet-like bodies in the main belt, Hilda, and Trojan asteroid populations. Intriguingly, the best solutions indicate there were once five giant planets: Jupiter, Saturn, and three ice giants, one that was eventually ejected out of the Solar System by a Jupiter encounter. We will discuss the evidence for this “lost" Neptune and how it affected both the small body and crater populations of the Solar System.

Short Bio: Bottke is the Director of the Department for Space Studies at Southwest Research Institute (SwRI) in Boulder, Colorado. He is also the Director of the Institute for the Science of Research Targets (ISET) of NASA's SSERVI Institute. His interests include planet formation, the nature of the early Solar System, and the evolution of asteroids, comets, and meteorites. He received a Ph.D. in Planetary Science from the University of Arizona in 1995, he was a Texaco Prize postdoctoral fellow at Caltech in 1996-1997, and was a postdoctoral fellow at Cornell University from 1997-2000. he joined SwRI in 2000. Bottke received the “Paolo Farinella Award” for his small bodies research in 2011, he gave the Shoemaker Lecture at the American Geophysical Union meeting in 2015, he became a Fellow of the Meteoritical Society in 2016, and he gave the Kavli Lecture at the 229th American Astronomical Society meeting in 2017. He is currently on the science teams for three NASA missions: OSIRIS-REx, Lucy, and Psyche. Bottke has also served as lead editor of the U. Arizona book “Asteroids III” (2002) and co-editor on “Asteroids IV” (2015).