Pluto is Not a Planet: Stu’s Argument

When I first heard the talk (which I believe happened many years ago) about Pluto not being a planet, I had two main thoughts:

  1. They’re right. It’s not a planet! (though this was not immediate… I had to think about it for a bit)
  2. I’m okay with them calling it a planet for tradition’s sake.

Many other thoughts came later, such as:

The scientific community isn’t much for tradition

Isn’t every natural (as opposed to man made) object orbiting the sun considered a planet?

Hmm… I guess they’re called “planetoids.” Or are they? Crap, I can’t remember.

Well, after some thought on the matter, I decided that Pluto was not a planet, and here’s why:

First off, all the outer planets were gas planets. Pluto was a solid. On top of that, it was tiny. Smaller than our own moon in fact. The fact that it had a moon itself helped the “it’s a planet” case a little, but not enough for me.

Second, it’s orbit is really weird. Here’s a layout that shows it’s distance from the Sun compared to other planets:

Ignore the red line. That’s the projected path of the New Horizons spacecraft.

Note that Pluto’s orbit is much farther “off center” than the others. So far off, in fact, that for part of its orbit it is actually closer to the Sun than Neptune.

If you were to rotate the above image 90° on the x- or y-axis (not around like a clock (z-axis), but “back”; like the way a clock’s hands would move if looking at it sideways), you would see that the 8 “traditional” planets orbit the Sun on the same plane. All the planets’ orbits vary “vertically” slightly, but do so very little. Which brings me to point #2. Pluto is the only “planet” that doesn’t orbit the Sun on that plane:

These two things I’ve know for most of my life. However, with the “Is Pluto a planet?” debate heating up, I decided to study up on the little ice ball a bit more. And that’s when I discovered what would be a bit of a clincher for me.

Turns out that Charon is not actually a moon of Pluto. I had always thought that Charon orbited around Pluto. After all, that’s what a moon is, right? An object that orbits around a planet. Well, turns out that Charon does NOT orbit around Pluto, nor does Pluto orbit around Charon. The truth is they orbit around the empty space between them. Some refer to this phenomenon as “dual planets”, a definition that suits me just fine. This occurs because the two objects are tidally locked (sometimes called gravitationally locked) to each other. By contrast, a moon would be tidally locked while the body it orbits around is not. Not all moons are tidally locked however.

So why have we called Pluto a planet for so long? I believe much of it comes from how Pluto was discovered. Way back in the 1920′s, astronomers miscalculated the mass of Neptune. These miscalculations made it appear as if there were some unseen gravitational effect on Neptune, causing unexplainable variations in its orbit. The most obvious explanation was that there was another planet (it had to be large enough to cause the variations on an object as huge as Neptune), so everybody was looking for this so-called “planet x.”

Clyde Tombaugh (whose story is rather fascinating in itself) was an amateur astronomer that, while looking for planet x, stumbled across Pluto quite by accident. Though Pluto’s status as a planet was debated early on, it was eventually decided that this was the fabled planet x, thus it was determined (though it be falsely so) to be a planet.

Decades later, thanks to a flyby of Neptune by Voyager 2, Neptune’s true mass was discovered and we all found out that there were no unexplained variations in its orbit, and therefore no outside gravitational effects acting on it.

Furthermore, Pluto’s orbit doesn’t ever bring it anywhere near Neptune, nor does Pluto (even combined with Charon) have anywhere near enough mass to affect Neptune’s orbit regardless of how close it ever got to Neptune.

There is some new data that makes Pluto an even more fascinating object. Turns out that there are two other “moons”: Nix and Hydra. Does that mean they both orbit around the “dual planets”, orbiting around both Pluto AND Charon? That would be pretty interesting. I have as of yet to find any information regarding the orbital behavior of these two newly discovered moons known as Nix and Hydra:

Anyway, to summarize: Pluto is NOT a planet! Thank you, and good day to you all.

7 thoughts on “Pluto is Not a Planet: Stu’s Argument

  1. Bryce

    It seems to me Stu that you are forgetting some very important facts in this matter, that have great influence upon the only logical conclusion: Pluto is indeed a planet.

    First of all, in your post you talk about the orbit of Pluto and show several diagrams of said orbit, all of which portray a 3 dimensional “solar system”. Excuse me, but everyone knows the world is flat, so how could the solar system be 3 dimensional?! Impossible!! I mean, really, check your sources.

    Next, being an alien abduction survivor, I have been to Pluto. It is the primary alien staging environment for human abductions, and let me tell you, it is also flat just like the earth, which further evidences the fact of its planety-ness.

    Thirdly, just because they come up with a few non-planetary diagrams and hold some convention in the same Hollywood theatre where they faked the moon landing, doesn’t mean its fact.

    So you see, despite all your supposed “scientific” evidence that Pluto is not a planet, REAL science always shines through, and Pluto will always be what it always has been: a planet.

  2. blooby

    ecuse me, but are u 2 messin around? or are u just controversial to scientific belief?
    1:universe IS 3D.
    2:None of the planets are flat.
    3:not many people will belive an ‘alien abduction survivor’, but pluto being a main place for aleins to live and abduct from there? even more far-fetched.
    4:moon landing DID happen.
    5:traditionally, pluto is a planet. scientifically, it ain’t!

  3. Yue

    hehehe of course they were joking around, seriously, my CAT knows that the world isn’t flat.

    Really, get a sense of humor, I think thats hillarious!

    thumbs up to you guys, you made my day!

  4. littlemisfortune

    First, before i poop the party, I just want to say that I thought the above comments were hilarious.

    Now, down to business. The argument its not a planet because ‘its orbit is really weird’ is a very unintelligent and invalid comment because it has no basis. So its orbit isnt completely like other planet’s, why is that a big deal that could change it’s ‘planet’ status? Your eye colour probably isn’t the same as mine, so does that mean your not a human being?

    Next, that ‘dual planets’ thing is saying Pluto AND Charon are both planets, right? And does the fact that we once believed that all the outerplanets were gas planets mean our understanding of them can’t change? Everyone used to think that what we now know as the Milky Way galaxy was as big as the Universe got and that sure changed.

    Who knows if Pluto’s orbit wasn’t thrown off course when meteorite hit it? In short, nobody really knows and everyone can say all they like about it but nobody will know in the foreseeable future if they’re right or not. All it is is opinions so heres my 1 cent worth: Pluto may or may not be a planet :) Who knows?

  5. littlemisfortune

    Also, not every natural thing oribting the sun is a planet. There are asteriods–sometimes called planetoids and comets. If you want to get technical, moons also orbit the sun because they orbit the planets that orbit the sun. Cheers.

  6. Stu

    littlemissfortune, if my eyes are red, then it’s worth looking into. But since my eyes are the same color as tens of millions of others, as are yours I’m sure… it’s still not safe to assume I’m human!

    Is Pluto a planet? Well, the scientists who make up the definition for what a planet is say “no” because Pluto does not fit the definition that they all made up while drunk on the best booze private funding can buy. But I say “no” because ITS ORBIT IS ALL WEIRD! :D


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