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Is {pluto|sedna} A Planet?
Dr. Zowie writes "NASA's announcement last week of Sedna's discovery reignited the debate
over whether Pluto is a planet. Dr. Alan Stern a noted planetary scientist and leader of the New Horizons mission to Pluto, pours on some gasoline with this
article in which he skewers the various arguments against Pluto-as-planet. Choice quotes include 'You wouldn't deny a chihauhau a place among dogs because it is too small,' and 'if your brain was so completely full of names of people that it just couldn't take any more, would anyone new who you met after that, therefore not be a person?'"
Although you have to admit that we NEED a planet named after the god of the dead. Perhaps we can put some trash out there and christen it.
What we call folk wisdom is often no more than a kind of expedient stupidity.-Edward Abbey
The two-legged things in my office have names?! Not just email addresses?
".. pours on some gasoline with this article..."
You haven't seen squat until you've seen astronomers argue.
How about the simple argument that planets are gravitationally strong enough to pull themselves into nearly spherical objects, whereas asteroids are not. Pluto, BTW, Sedna, and many of the largest moons can all do this.
I also think, for the record, that if something as large as Luna, or Titan, or Europa were out floating in space orbiting the sun and not another planet, they would be considered planets too.
A problem with this is that there really is no clear-cut differentiation between "planet" and "planetoid". There's no qualifying size-- it's more subjective than anything. Almost like different species: we all differ genetically, yet a species is a generally-recognized "set".
One agreed-upon qualification is being formed round by its own gravity. I'm not sure if that applies to Sedna.
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Th proposal in the article is that every body that is rounded by it's own gravity (apparently this happens at a few hundred kilometres) should be considered a planet. Actually sounds a reasonable definition to me.
The Atlantic Monthly had an article about the Pluto situation years ago. The problem, though, is that "kids love Pluto." Scientists have tried to change names before (such as the dinosaur example). It'll be interesting to see what the public says about Pluto's demotion (if it occurs).
"You wouldn't deny a chihauhau a place among dogs because it is too small."
Dog? I always that chihauhaus were large rats.
My charts are going to have to all be recalculated if Sedna is a planet. What a PITA if there ends up being 900 planets! How will I ever be able to calculate this week's horoscope before the week is up?
We should have stuck to the original five. Mercury, Mars, Venus, Jupiter and Saturn. Earth doesn't count, since all these revolve around it.
Let's not mess with our destinies. Don't upset the natural systems any more.
Honestly, who cares.
:P
It's not like there's some legal reason to have the definition of a planet rigidly defined, it doesn't effect the money anyone gets, it doesn't influence political boundaries, and it won't get anyone out of jail.. so who cares?
If it's big, it's a planet. If it's not big, it's an asteroid. If it's not big and made of ice, it's a comet.
Might as well debate which text editor is bettor or whether we should be putting GNU in front of Linux.. it's such a silly thing to discuss it baffles me this shows up in the news so often.
I think part of the problem is the fact that memorizing the 9 planets are all most people really know about our solar system, and so they tend to be fairly sentimental about it. I think a much more accurate and interesting approach to teaching kids would be to start of by brainstorming all the different types of objects in space - galaxies, solar systems, stars, moons, astroids, comets, nebulas. Then instead of memorizing just the planets memorize all the different regions of our solar system and what makes them special. Start with the sun, then you get to the inner planets, then astroid belt made mostly of rock, then giant gass planets, then the Kupier Belt full of icy objects and finally the Oort cloud. Then lastly you describe the interesting features of each area, including the planets and what makes them unique.
This journey approach would be far more interesting to the kids and by the time you got to the point of describing pluto and charon, they would have an understanding of how diverse (for lack of non PC word) matter in space is and would be less concerned about sticking a specific catagory on it, and just be excited that it was yet another unique and interesting thing.
It's the difference between decribing the cool terrain, people and features in country as opposed to just memorizing the state capitals. The former is far more interesting, and informative, and kids will eat it up.
chihauhaus are clearly rodents, not dogs. Therefor, Sedna is not a planet, but a rodent.
One future, two choices. Oppose them or let them destroy us.
How about the simple argument that planets are gravitationally strong enough to pull themselves into nearly spherical objects, whereas asteroids are not.
:)
:) But clearly a planet-sized object orbiting another planet is a moon. Again, this definition makes perfect sense.
:)
I like this definition a lot. While it does leave some wiggle room as to what exactly constitutes "spherical", it is still based on a physical property of the object related to its mass. This makes it better than any arbitrary size/mass requirement (e.g. "Anything as big or bigger than Pluto").
Pluto, BTW, Sedna, and many of the largest moons can all do this.
I'm going to be extremely unhappy with any definition that demotes Pluto. Also, anything that makes Pluto not a planet is going to be close to making Mercury not a planet, and that's just not acceptable.
I also think, for the record, that if something as large as Luna, or Titan, or Europa were out floating in space orbiting the sun and not another planet, they would be considered planets too.
Titan is bigger than Mercury, so a Sun-orbiting Titan not being considered a planet is unacceptable.
I'm not an astronomer (but I play one on occasional weekends), but of all the definitions I've heard, "big enough to be spherical and orbiting a star" is the simplest and most logical.
And for the record -- if there was some comet out in the Ort cloud with an incredibly eccentric orbit around the sun that was the size of Titan, that'd be a planet too. IMHO.
The enemies of Democracy are
What!? As any child can tell you, fruit tastes good, whereas vegetables are ucky. Therefore, the tomato is a vegetable. (Unless it's used in pizza sauce, at which time it is cast as a fruit)
The definition that makes Pluto not a planet is not based completely on arbitary size and so would probably not demote Mercury as well. The most prevalent definition of a planet (which was not stated in the article as far as I could tell, at least not completely) is any gravitationaly round object that is more massive than the rest of the mass in a similar orbit COMBINED. Mercury would be safe with this definition, while Pluto would be quickly tossed out. I actually like this better as the term "planetoid" now means something different than either "planet", "asteroid" or "satelite." (it would become a synonym of one of these otherwise) I propose the following definitions:
Planetoid: Any object that becomes round by its own gravity but does not sustain fussion.
Moon: Any planetoid that orbits another planetoid (let's face it, it's a generic term and nothing will ever change that). BTW: This would demote a lot of "moons" to mere satelites.
Planet: Any planetoid that is more massive than the the rest of the matter in its orbit combined.
common sense: noun
What those who are ignorant of the subject matter think; usually wrong.
I bet the folks who live on Jupiter think our solar system only has 4 planets. After all, Earth and Venus aren't so much bigger or different than Pluto or Sedna. Certainly, Earth is closer in size to Pluto than to Jupiter.
People argue so much over where to draw the line between Planet and non-Planet, but everyone seems to take for granted that Earth is a member of the former class.
Bigots.
Paranoid
Bwaahahahahaa.
Tomatoes are planets.
Know your pads. One time pad: good for cryptography. Two timing pad: where to take your mistress.