Today's the anniversary of the discovery of Pluto. As in the planet. As in-- these days -- the planet NOT. The Un-Planet. But back in 1930 Clyde Tombaugh found Pluto in the skies just past Neptune. And suddenly we had Nine Planets in the Solar System.
I remember in the latter days of the 20th century (like the 90's) our great leader explaining in great detail why Pluto is no longer a planet. He didn't mind bursting our bubble. In fact, he seemed to kinda enjoy it. Like saying there's no Tooth Fairy, no Easter Bunny, no Santa Claus (not a Sanity Clause either).
Before we go into the whys and wherefores you may be wondering just who is our leader? Why it's Neil DeGrasse Tyson, the head of the Hayden Planetarium at the American Museum of Natural History in New York. Not only is he a topnotch top-gun astrophysicist he knows how to tell you about what's up there, too. I took two classes from him. One: Space Science: An Introduction. The other: Astrophysics Roundtable. He'd get up on the auditorium stage and pace about as he spoke, writing things on the board, making diagrams, answering questions, all with such happy passion, it made you think that wallowing in the cosmos all day and night was a lot better than grocery shopping and worrying about the latest crimes and scandals on the news. Imagine always looking at the BIG picture.
I actually understood things like kelvins and energy production formulas and nucleons and inverse time and cosmological constants and equations for thermonuclear fusion. I'm not even a science person. But he made it all clear. Until I left the auditorium. Then it became a jumble in my head and rapidly dissolved into anti-matter. But the time in the class was precious. The whole universe sparkled with clarity.
Why is Neil our leader? (All of his students are supposed to call him simply Neil.) Because when the aliens land and inevitably say: "Take me to your leader," this is the guy we should take them to.
So Neil said there ain't no planet called Pluto. He says Pluto has peculiar written all over it. He says it's a leftover comet. It's too small to be a planet. It's made of a lot of ice. Its orbit isn't planetary like the rest of our planetary planets. Its tipped and not really following our solar system rules. Now it's called a Kuiper belt object (talk about a demotion!).
But, it's cute. And it's terribly hard to give up on an old friend. Especially one named for a cartoon character.
I suppose if we accept the rule-players and stick with the nice neat number of 8 planets, we'll have our solar system all tied up prettily in a bow. But for those of you (I'm not necessarily saying me. Remember I was in Our Leader's class) who are more comfortable with letting the marginalized IN, you can call Pluto to dinner when Jup, Sat, Merc, Mars, Ear, Ura, Nep, and Venus come over. You can let Pluto sit by the fire to warm up. Tell him he's not really an object at all. Except an object of your affection.
Neil is wrong about Pluto for several reasons:
ReplyDelete1. Pluto as a planet is not in a category of one. There are several of these smaller
planets that need to be distinguished from asteroids because their makeup is exactly like
that of planets in that they are in a state of hydrostatic equilibrium. This means they
have enough self gravity to pull themselves into a round shape, which makes them
geologically like the larger planets and unlike shapeless asteroids and
comets. Tyson never discusses hydrostatic equilibrium and blurs this crucial distinction
by lumping Pluto and other small Kuiper Belt planets with comets and asteroids.
2. The scientific community has not made a final decision on this matter. This definition
was adopted by only four percent of the IAU, most of whom are not planetary scientists.
No absentee voting was allowed. It was done so in a highly controversial process that violated the IAU’s own bylaws, and it was immediately opposed by a petition of 300
professional astronomers led by Dr. Alan Stern, Principal Investigator of New Horizons,
saying they will not use the new definition, which they described accurately as “sloppy.”
Also significant is the fact that many planetary scientists are not IAU members and
therefore had no say in this matter at all.
Many believe we should keep the term planet broad to encompass any non-self-luminous
spheroidal object orbiting a star.
Tyson also contradicts himself on the IAU vote. On the one hand, he rightfully describes it as "flawed" and disavows any connection with it. On the other hand, he cites it to vindicate his decision to exclude Pluto from the planet display at the Rose Center. Which one is it?
3. Support for Pluto's planethood is not limited to Americans. I have personally received emails from around the world opposing Pluto's demotion, and there are Internet groups worldwide committed to seeing Pluto reinstated. Many songs and poems opposing the
demotion were written by people other than Americans.
4. Tyson's claim that people's emotional attachment to Pluto is largely due to the Disney dog is at best questionable. Most Pluto supporters are astronomy enthusiasts with a
strong interest in the solar system. They view the solar system as a "family," and see a round object that looks exactly like a planet and find it bizarre that anyone
would categorize it as something else.
5. Tyson's comparison of Pluto with comets is a red herring. Yes, if brought into Earth's
orbit, Pluto would begin sublimating and appear to grow a tail. However, so would any
planet brought close enough to its parent star. If Earth were placed in Mercury's orbit,
it would appear to grow a tail as well. Pluto is also far larger than any comet, and its
orbit never takes it into the inner solar system. Significantly, a large exoplanet, HD80606b, was just discovered, which is four times the size of Jupiter and orbits its star in only a few days, yet has a comet like orbit. Is this object, which is bigger than any in our solar system, not a planet but a comet because of its elliptical orbit? Clearly, "comet-like" orbits alone do not make objects comets instead of planets.
Please feel free to visit my Pluto blog at http://laurele.livejournal.com for more
information about the other side. I am planning to write my own book on Pluto presenting this viewpoint.
Thanks so much for presenting this view of Pluto!
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