Professor Kate Daniel and Swarthmore students Noah Lifset and Luke Barbano presented their summer research poster at the 229th Meeting of the American Astronomical Society in Grapevine, TX (#aas229) and were tweeted as the favorite poster of the day by Astronomy on Tap (https://twitter.com/aotatx/status/817828584492584960). Luke and Noah’s research focused on simulating the motions of stars in the disk of spiral galaxies. They showed that tightly wound spirals will likely have less of an impact on the evolution of a galaxy while open spiral arms would tend mix stars across the disk through a dynamical resonant interaction.