Frontiers of Astronomy: Pluto’s Lonely Ice Cap

Date: Thu. October 13th, 2016, 8:00 pm-9:00 pm
Location: Cleveland Museum of Natural History, 1 Wade Oval Drive, Cleveland, OH 44106

Pluto’s Lonely Ice Cap

Doug Hamilton, University of Maryland

The icy white heart of Pluto became an instant sensation after the 2015 New Horizons flyby, featured on websites, blogs, and T‐shirts worldwide. The actual feature on Pluto is composed of frozen nitrogen, carbon monoxide, and methane, substances that can all be either in the solid or gaseous states at the cold temperatures of this distant world. Water plays the same role on Earth, being found as a solid in our twin polar ice caps, and Mars too has a pair of polar caps composed, in this case, of both water and carbon dioxide ices. So is Pluto’s heart also an ice cap? If so, then unlike Earth and Mars, Pluto has only a single ice cap. Even more surprising, the feature is centered at latitude 30 degrees, about the location of Florida on Earth. Finally, Pluto and its large moon Charon are tidally locked such that the moon is only visible from one hemisphere of Pluto; Pluto’s heart and Charon are on opposite sides of Pluto, a seemingly striking coincidence. In this talk, I will explain how all of this is related: that 30 degrees latitude is the coldest part of Pluto, how all of Pluto’s ices became concentrated in one spot, and how that spot found itself facing nearly opposite the direction to Charon.

Doug Hamilton is a Professor in the Astronomy Department at the University of Maryland. His research interests are focused on Planetary Science with specializations in moons, rings, and orbital dynamics. He is co‐discoverer of Saturn’s Phoebe ring and the two smallest moons of Pluto, and is also a member of NASA’s New Horizons and Juno missions to Pluto and Jupiter.