Big Picture Science – A Sudden Change in Planets: David Eicher / Planetary Designations

by Gary Niederhoff on September 7, 2014

A Sudden Change in Planets – David Eicher
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Part 5 of A Sudden Change in Planets, featuring David Eicher, editor-in-chief of Astronomy Magazine, discussing how criteria are established for planetary designations, and how those designations are simply a matter of semantics.
(TRT 8:31)

{ 2 comments… read them below or add one }

avatar Adrian Morgan September 14, 2014 at 6:50 am

People really should know better than to use the tired out argument that “asteroids in resonance with planets exist, therefore planets haven’t cleared out their zones”.

Yes, the phrase “cleared out” is clumsy. Time to move on. The very fact that a smaller body’s orbit is tied to that of a larger one only reinforces the fact that the larger body is particularly influential and belongs in a special category. It cannot be used as an argument against.

avatar Laurel Kornfeld September 14, 2014 at 3:55 pm

Being in a resonance with another planet does not itself make an object not a planet because it does not change that object’s inherent characteristics. There are several exoplanet systems in which two giant planets are in the same 3:2 orbital resonance as Neptune and Pluto. Does that make one or both of those not planets?

Time to move on from a bad definition that defines object by location, meaning the very same object can be classed as a planet in one location and not in another. The use of the adjective “dwarf” tells us that a particular planet is too small to influence other bodies, which is why it merits being classed as a different type of planet than its larger counterpart.

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