Neil deGrasse Tyson

Mark Worden (Standard British accent):

The April issue of Speak Up features an interview with Neil deGrasse Tyson, author of the book, The Pluto Files: The Rise and Fall of America’s Favorite Planet. In this out-take he explains why Pluto was “declassified”:

Neil deGrasse Tyson (Standard American accent):

Today, it’s not a planet and that became official in 2006, when the international community of astrophysicists voted on the new definition of a planet. And that new definition excludes Pluto and the new definition has three rules about it. First: Are you round? Well, Pluto is round, so Pluto gets a check in that box. Another one is: Are you the primary object that’s orbiting the Sun, as opposed to a secondary object, like a moon: Pluto’s a primary object, put a check in that box. The third criterion was: Have you cleared your orbit of debris? And Pluto orbits the Sun in a zone that is filled with thousands of other small icy objects, in the outer solar system. So it has not cleared its zone. Other planets have: Earth has cleared its zone. Yes, we collide with asteroids every now and then, but they’re very small, compared with Earth. We have objects out there with Pluto; some are as large as Pluto. So Pluto does not dominate this outer zone of the solar system. It does not get a check in that box, therefore Pluto is not a planet.

(Neil de Grasse Tyson was talking to Lorenza Cerbini)
For more on Neil deGrasse Tyson, visit: http://www.haydenplanetarium.org/tyson

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