Wednesday, February 22, 2017

"All These Worlds..."

I'm fascinated that the argument over the definition of the archaic word "planet" simply refuses to die. On the one side of this ongoing non-controversy we have those who respect the current IAU definition and argue that we have eight planets in the Solar System plus an odd number of dwarf-planets (including Pluto, Ceres, Eris, etc.). On the other side of acrimony we have those who pine of the good 'ole days of "My Very Educated Mother Just Served Us Nine Pizzas" and can't abide the IAU decision.

But wait. Now we have a THIRD side, demanding that EVERY object that orbits the Sun is a planet--which will give us an impressive catalogue indeed!

Personally, I think that we need to dispense with this entire debate. We are making the mistake here of trying to squeeze the incredibly numerous and varied bodies that orbit the Sun into very small taxonomical boxes by forcing them all into some new, all-encompassing, impossible definition of a single word.


The term itself is unfit for our purposes. Meaning "wanderer" It's based on an ancient word applied in its era to the five naked-eye bodies that wandered in the skies of Babylon and Athens. Sometimes also applied to our Moon and passing comets, it simply isn't enough for today's Solar System.

Try on a different word: "Worlds".

When I speak to students who visit the Abbitt Observatory I use this word rather than "planets" because it better represents the bodies of the Solar System as we know them today; not as unknown and un-knowable points of light that inexplicably brightened and dimmed as they traced mysterious paths across the ancient heavens but as what they are to us in this modern era; actual places that can be visited and explored, studied and understood in all their sizes and varieties.

Earth is a world; there can be no debate on this. So is Mars. And the Moon, Vesta and Ganymede; all worlds. Tiny Pluto, giant Jupiter, icy Comet Halley and all the myriad objects in the Kuiper Belt...the word applies to them all broadly, without need of division or amplification.

Within the massive catalogue of worlds there are giants and pygmies, from super-Jovian exoplanets down through the scales to the smallest aggregations of rubble to be found in the Main Belt. Of course there is need of classification within the broad context of Worlds, but no requirement for time-and-energy wasting argument regard the very meaning of the term!

"Planets" are passe; open your mind to other Worlds.

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