Planethood

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Last Sunday evening i helped Veronica study for her astronomy test. during the course of this very interesting task, the status of Pluto as a dwarf-planet came up for discussion.

Apparently ‘planethood’ is not defined as a body orbiting the sun, but rather a body of a certain size orbiting the sun – and this size is defined as ‘having enough gravitational force to clear it’s own orbit.’ For those of you who are having a similar reaction to mine (what the hell does that mean?) – Pluto is not big enough to ensure that it does not go catapulting into stuff on it’s way around the sun.

Ok. Now – why the sudden change? What could possibly possess astronomers to strip Pluto of planet-status all of a sudden and to the chagrin of a generation of schoolchildren who learnt the catchy mimetic device My Very Educated Mother Just Served Us Nine Pizzas to learn the order of the planets.

Firstly, apparently a rather large asteroid has been discovered in the belt between Mars and Jupiter that would be a planet if the size criteria were in place. Apparently it made more sense to reduce the number of planets orbiting our sun to eight rather than increase it to ten (or eleven… i think there’s another dwarf-planet past Pluto). Ironically, the astronomer who came up with the ‘orbital clearance’ criteria refuses to call Pluto a dwarf-planet.

So… is Pluto a planet or not? Depends on who you ask. It’s amazing how even the most concrete things can get bogged down in definitions.

Lastly, i provide a thought-experiment for your general amusement. Yes… it is reductio ad absurdium, but i don’t care. I think it’s funny.

If i were so fat, stinky and otherwise unattractive that as i walked around on the planet Earth i repelled all other people… might i too be considered a planet? I would, in effect, be orbiting the sun with a cleared orbit… LOL.

Thanks to Wikipedia and Veronica’s astronomy textbook, which i will not go searching in her room for because that would be rude, for this science lesson.

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