In 2006, when the International Astronomical Union (IAU) voted on the definition of a “planet” and booted Pluto out of the club, confusion resulted. Was a “dwarf planet” a small planet or something else? Was a “dwarf fruit tree” a small tree or something else? Almost eight years later, most astronomers and the public are still as uncertain about what a planet is as they were back then.

On September 18th, three different experts in planetary science will present each of their cases as to what a planet is or isn’t. Science historian Dr. Owen Gingerich, who chaired the IAU planet definition committee, will present the historical viewpoint. Dr. Gareth Williams, associate director of the Minor Planet Center, will present the IAU’s viewpoint. And Dr. Dimitar Sasselov, director of the Harvard Origins of Life Initiative, will present the exoplanet scientist’s viewpoint.

After these experts have made their best case, the audience will get to vote as to what a planet is or isn’t and whether Pluto is in or out. And just like the IAU, you have to be present to cast your ballot! The results will be announced on Friday, September 19th.

Watch It Live

Date: Thursday, Sept. 18, 2014
Time: 7:30 p.m. EDT
URL: http://www.youtube.com/user/ObsNights

The talk will also be archived on the Observatory Nights YouTube channel immediately following the event.

Contacts:
David Aguilar
+1 617-495-7462
daguilar@cfa.harvard.edu

Christine Pulliam
+1 617-495-7463
cpulliam@cfa.harvard.edu

Observatory Nights are held at the Harvard-Smithsonian Center for Astrophysics (CfA) on the third Thursday of every month during the academic year. These talks cover a variety of timely astronomical topics. Observatory Nights take place at Phillips Auditorium, 60 Garden Street, Cambridge, Mass.

Then-observatory director Harlow Shapley founded the “Observatory Nights” program in 1930 in order to give the public an opportunity to learn about astronomers’ latest discoveries and to view the cosmos through telescopes. More than 80 years later, Shapley’s prescience is confirmed and Observatory Nights are still going strong, reaching ever-wider audiences online.