Pluto, By Any Other Name …

Sky and Telescope MagazineI’m reading about the Great Planetary Demotion controversy again in the current Sky & Telescope (November 2006).

Since every school kid had to memorize the names of the “nine planets”, the media has picked up on this one. Any change in the conventional thinkiing that impacts the study habits of school kiddies is fair game for the press.

As you surely know and are getting tired of hearing, the IAU recently tightened the definition of “planet” to include the requirement that a planet candidate be massive enough to sweep the geophysical space surrounding its orbit clean of asteroidal debris. Poor tiny Pluto, which is smaller than Earth’s Moon, plows smack through the middle of the Kuiper Belt on a highly eccentric orbit. Exactly how a planet of any size is expected to clean up that mess, is not explained.

The IAU voted to demote Pluto to “dwarf planet” status, and the rest is history – history, at least, until the next IAU conference where it’s widely expected astronomers will take a second look at this decision.

Legendary astronomer and observer Clyde Tombaugh discovered the “missing ninth planet” in 1930. The impetus for this siren-call discovery was predictions by Herschel and others that perturbations of the orbits of Herschel’s new planet Uranus would be explained by the discovery of an outer planet. The discovery of Neptune in 1846 didn’t fully resolve this. Tombaugh, who died On January 17, 1997, remains an inspiration to millions for his perseverance and persistence in often brutal observing conditions and gruelling blink-comparator sessions.

I’m not reading any more celebratory memorabilia about Tombaugh’s famous ninth planet exploit right now. It’s almost like there’s a self-enforced cone of silence in the astronomy and news communities regarding the remarkable context of Pluto’s discovery.

I am reading some new memnonics which aid kids and news writers alike in memorizing the planets. I never heard these before. One was “My Very Excellent Mother Just Served Us Nine Pizzas.”

Before Pluto’s discovery in 1930, of course, kids memorized eight planets. The memnonic (taught to me by my mother) was: “Men Very Easy Make Jugs Serve Useful Needs.”

After that, it became the only memnonic I ever knew (taught to me, you guessed it, by my mother):

“Men Very Easy Make Jugs Serve Useful Needs. Period.”

That pretty well sums it up for me.

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