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What Pluto Really Is

Updated on April 22, 2010

Pluto orbits near the edge of the organized solar system

This is a depiction of Pluto based on the most recent information available.
This is a depiction of Pluto based on the most recent information available.

Pluto; a proto planet in transition

Pluto is one of thousands of planetesimal sized Trans-Neptunian bodies. For the last few years there has been a raging debate as to whether Pluto is a planet or not. As Pluto is orbit about the sun, it can be considered a planet, except for its diminutive size, which is why it was "demoted". Pluto has a companion, Charon, which one can say is a moon of Pluto. In reality, Charon is another planetesimal which happens to be in orbit around Pluto and shares the same relationship with Pluto. Pluto is caught in a curious two to three resonance with Neptune, which stabilizes its orbit, because it never gets close enough to Neptune to be pulled into or ejected out of the solar system. For every three of Neptune's orbits, Pluto and Charon orbit twice. Pluto belongs to the family of inner Kuiper Belt objects.

Pluto and Charon as well as all the other Kuiper Belt planetesimals exist well beyond the freeze line of the solar system. They are made primarily of volatiles that were blown out to the Kuiper belt and began to accrete into planetesimals. As evolution occurs more slowly at those distances from the sun, about 39 AU and more, Pluto, Charon, Sedna and many others can be seen as planetesimals in evolution toward planet-hood. Evolution has already been more or less completed nearer the sun, so we have the terrestrial planets, Mercury, Venus, Earth/Moon and Mars. There are the gas giants past the freeze line consisting of Jupiter, Saturn, Uranus and finally Neptune. Asteroids and comets exist in profusion throughout, clustering into discrete regions.

Pluto represents the seed of another type of body. It is neither rocky planet nor a gas giant planet. It is made up of volatiles like methane, ammonia, water ice and other hydrocarbons. These molecules were too far out to be collected by the gas giants and their moons. By accretion stages that are identical to those forming the Earth and the other major planets, Pluto, Charon, Sedna and thousands of others are slowly growing in size. They are still under evolution. What remains is competition for material by absorbing smaller planetesimals. Due to their distance from the sun and their as yet weak gravitational influence, their evolution takes billions of year as opposed to the millions it took to form the terrestrial inner planets.

Will Pluto win the race to planet-hood? That depends on a number of factors that are as yet unclear. We know that comets can be drawn into the inner solar system by disturbances from passing stars and that these will cross the orbits of all the planets. Some Like Chiron caught between Saturn and Uranus in a 56 year orbit originated from the Oort cloud or the inner Kuiper belt. Sedna in its highly eccentric orbit appears to be a body in transition. Sooner or later, something will impact Pluto. Depending on its size, this will alter the orbit of Pluto to something different than it is now. For the moment we know of nothing that is due to hit Pluto. Meanwhile, it continues to slowly collect space dust that is in orbit in the Kuiper Belt. It will be a long time before it crosses from the planetesimal stage to a full fledged planet. But, as Pluto has gravity and can Clearly grow by gravitational accretion as evidenced by its hold on Charon, it is more than just something "other than a planet".

Were Pluto always inside the orbit of Neptune, it would have been a contender for full fledged gas giant planet-hood. Pluto though is in an eccentric orbit of its own, spending only a short portion; eighteen year of its 247 year period inside the orbit of Neptune. It is thought that Neptune attracted it out of the Kuiper belt, but as it got caught in a stable two to three resonance orbit, it has not been fully captured and remains as we see it now. It is this peculiarity that caused the debate about Pluto's status at the outset.


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    • profile image

      tom richards 2 years ago

      Is Pluto a plant when I when to school yes we call it a plant

    • syzygyastro profile image

      William J. Prest 6 years ago from Vancouver, Canada

      In that windstorm, I saw two trees fall close to where I live and work. Later, in a period marked by months as the park was impassible, I saw damage to literally thousands. One has become something of a landmark near the entrance and has not been removed. It is right next to a large downtown marina.

    • somethgblue profile image

      somethgblue 6 years ago from Shelbyville, Tennessee

      and again I ask how many did you personal watch fall?

    • syzygyastro profile image

      William J. Prest 6 years ago from Vancouver, Canada

      I've seen trees blown down in a high wind by the hundreds without a single ax swing to bring down any one of them. I lived through the horrific wind storm of Dec. 14, 2006 that brought down a quarter million trees in our region. That same storm blew out windows all over the place and deafened a friend of mine when one exploded with a bang beyond sound. The damage to a local park and tourist haven was so devastating that it took loggers over a year to pull out the felled trees post storm. I took pictures of trees that I saw blown down. One of them even managed to live for a couple of years despite being toppled. So, there are times of tumult where people can witness events like this. The wind was so strong that night is was all one could do to stand let alone attempting to film anything.

      One does not have to see Pluto, Neptune or Uranus to appreciate their effects and for that matter, one does not have to see the moon due to clouds to appreciate the effect of lunar driven tides.

    • somethgblue profile image

      somethgblue 6 years ago from Shelbyville, Tennessee

      Personally I don't think the tree fell, after all how many trees have you actually witnessed in person falling without being chopped down.

      If your honest you will say Zero and neither have I, there is a reason for that!

      This hub was very well written!

    • syzygyastro profile image

      William J. Prest 6 years ago from Vancouver, Canada

      The last question is something akin to the question "If a tree falls in the forest and no one is there to witness it, did the tree indeed fall?" I believe, with evidence to back it up that high civilization has existed before and new about the outer planets and more. This was recorded and passed down along with various technological wonders that form today's out of place artifacts (OOPArts). Pluto has existed for a long time and exists in a stabilized 3:2 orbital resonance with Neptune.

    • somethgblue profile image

      somethgblue 6 years ago from Shelbyville, Tennessee

      What I find amazing is that ancient Sumeria knew of its existence even replicating it on temple walls, how did they know?

      My question is if we didn't recognized its existence until 1930 does that mean it didn't exist?

    • astrohypnotist profile image

      astrohypnotist 6 years ago from Whiteville, NC

      I totally agree with you. I have been teaching children since the early 90's that I believed that in the future, Pluto would no longer be considered a planet. And I believed it was probably the largest kuiper object.

    • Bharatthapa profile image

      Bharat Thapa 6 years ago from NEW DELHI

      I am impressed with your work, these information's are so least expected and hard to find but good to see such information's.

    • Jasnav profile image

      Jasnav 8 years ago

      Nice hub there!

      We grew up learning Pluto is the ninth planet of the Solar System, so it did come as a shock of sorts to be told otherwise (not that it affected our lives significantly lol!)

      At least I now know why. Thanks!