Defining a Planet

That astronomy struggles to define what a planet is I find astonishing. I've long suspected that our science and tremendous collected knowledge isn't quite as wonderful and advanced as we always assume it is. Humans judge things quite subjectively, and whether we realize it or not we are hardly as enlightened as we may believe we are. Knowledge we can only compare to the past so it always appears we are at a peak of dizzying heights, especially because we may well simply be ignorant or unable to value what humanity has achieved in the past.

Losing Pluto as a planet (when just about everyone but astronomers knew it was a planet) was a great reminder that science isn't always so omniscient, no matter how much we wish it were. And the Sol-centric definition was so provincial. Anyone who has watched Star Trek knows they call those big round worlds "planets" no matter what star they orbit. Just try imagining Kirk asking to be beamed down to the "exoplanet" they are visiting to see how absurd limiting the definition to our solar system is.

A new definition is proposed now at arrive [PDF] that strikes me as still missing the point. While I cannot say I read and understood the entire paper I don't think that classifying something as a planet based on numerical observations itself is a good idea.

1. our observations will always be subject to errors and need revision
2. any numerical threshold will be arbitrary
3. if astronomers want to make technical classifications of orbital bodies, define new terms instead of hijacking old familiar ones

In conclusion, I say let people call what they will a planet and don't worry about it. That is, I think scientists easily confuse language as being some kind of scientific data, instead of what it is which is just our human tool for communicating. Simply providing observed data about the object is a far better description that relying on nomenclature.

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