How Planets Form – With Guest Dr. Eric Mamajek (Part 1)

February 18, 2013

John P. Millis, Ph.D. for – Your Universe Online

How did Earth form? For centuries, this question has both puzzled and inspired astronomers. But as we have begun to understand the nature of stars and their formation, we’ve also developed and explored theories about how this process gives rise to planets.

Until very recently, our primary laboratory for conducting research has been our very own solar system, as it was the only planetary system for which we had much data. In the last decade, however, a wave of exciting new discoveries has triggered new questions about how planets form.

In this first installment of our three-part podcast series, we explore current theories about how worlds form and even examine the definition of a planet. We also took the opportunity to discuss the 2006 controversy whereby Pluto was stripped of its status as a planet. Our guest Dr. Mamajek – himself a member of the organization that was behind the decision to demote Pluto to the rank of dwarf planet – will talk about the factors that led them to this decision.

In parts two and three of this series, we will look at the relatively new field of planet hunting – how we search for planets outside our solar system, what has surprised us and where the field is headed. The series will conclude with a discussion of the possibility of finding other Earth-like planets and why we think – or don’t think – we might find life elsewhere in our galaxy and beyond.

Listen to parts two and three of the interview, “Planet Hunting” and “The Search For Alien Life.”


Eric Mamajek is Assistant Professor of Physics and Astronomy at University of Rochester. He received his B.S. in Astronomy and Astrophysics, and Physics, from Pennsylvania State University in 1998 before completing a M.Sc. in Physics from The University of New South Wales/ADFA in 2000, and a Ph.D. in Astronomy from The University of Arizona in 2004. After his Ph.D. he was a Clay Postdoctoral Fellow at the Harvard-Smithsonian Center for Astrophysics, and he joined the faculty at University of Rochester in 2008.

His primary research interests are understanding the formation and evolution of stars, planetary systems, substellar objects, and circumstellar disks in our Galactic neighborhood. He has coauthored over 80 refereed astrophysics journal papers, and his research has been supported by awards from the National Science Foundation (NSF) and the National Aeronautics and Space Administration (NASA). In 2012, his research group announced the discovery of the first ring system outside the solar system which transits a young Sun-like star, and in 2010 he and his collaborators discovered a faint stellar companion to the famous star Alcor in the Big Dipper.