Pluto and its moon, Charon

Frontiers of Astronomy Lecture Series: “Pluto’s Lonely Ice Cap”

Pluto and its moon, CharonAs part of the Frontiers of Astronomy Lecture Series, renowned astronomers from across the country will give free lectures at the Natural History Museum throughout the year.

In cooperation with the Cleveland Museum of Natural History and the Cleveland Astronomical Society, the Department of Astronomy, through the support of the Arthur S. Holden, Sr. Endowment, sponsors the 2016-2017 Frontiers of Astronomy Lecture Series.

The next installment of the series will feature a talk by Doug Hamilton, professor of astronomy at the University of Maryland, who will present “Pluto’s Lonely Ice Cap.”

Hamilton’s talk will be held Thursday, Oct. 13, from 8 to 9 p.m. in the museum’s Murch Auditorium.

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, Hamilton 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.