Pluto's Planet Status: The Truth About the Ninth Planet of Our Solar System

  • Thread starter Loren Booda
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In summary, since young Earthlings have been told that Pluto is the ninth and outmost planet of our solar system, recent information has revealed that it is actually a binary planet along with Charon. Clyde Tombaugh, an American amateur astronomer who was held up to us as an example of dedication during the Cold War, is credited with discovering Pluto. Whether or not it is a planet, depending on your definition, is somewhat arbitrary.

"Pluto": what's it to you?

  • Not a planet

    Votes: 5 21.7%
  • A single planet

    Votes: 10 43.5%
  • A binary planet

    Votes: 5 21.7%
  • Other (explain below)

    Votes: 3 13.0%

  • Total voters
    23
  • #1
Loren Booda
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Since I was a young Earthling, I had been told that Pluto was the ninth and outmost planet of our solar system.

More recently, I have heard that Pluto did not form with the rest of our planets, had actually been captured late in the game, and therefore was not a planet at all.

Today I ventured with my girlfriend (also an Earthling) to the National Air and Space Museum, where we were informed that Pluto is actually a binary planet, along with its "moon" Charon.
 
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  • #2
I voted "other" because I don't care one way or the other. I will always remember Clyde Tombaugh because he was held up to us who grew up in the Cold War as an example of what a dedicated amateur could aspire to. When Sputnik was launched in 1957, suddenly US schools started taking sciences a bit more seriously, and Clyde was a handy role model. Yeah, Pluto is tiny and it has an inclined, elliptical orbit...it is least like the other planets in many respects, but who cares how it is classified? If it is classified as a "planetoid" or some such, teachers will have to spend time explaining its "demotion", and it will get more attention that way than it does currently.
 
  • #3
It really depends on your defintion of planet, some people like to thik of it as the smallest planet, this is mainly for historical reasons, others like to look on it as the largest object in a group of objects much more abundant than the planets - the planetoids. Arguably defining it as a planetoid is more objective than defining it as a planet, but then again the whole excerise as defining it as planet vs planetoid is fairly subjective.
 
  • #4
If pluto-charon is considered a "binary" system, then certain earth-luna should be also!
 
  • #5
Mike Brown of Caltech [co-discover of Quaoar] made this comment. "If Pluto were discovered today, no one would even consider calling it a planet because it's clearly a Kuiper Belt object."
 
  • #6
A single planet!
It's only charming that it is a bit weird..
 
  • #7
How many Kuiper belt objects are now considered to be in planetary orbit(?) around Sol and of sufficient mass(?) to be planetoids?
 
  • #8
It's a member of the EKB, just like several thousand others. Its uniqueness is twofold - it's the largest (so far) and first to be discovered (being a binary is not unique - not only is Earth-Luna a binary, but there are at least 5 other EKB objects which are binary).

As to Loren's question, it depends on your definitions. AFAIK, EKB objects aren't categorised by size (no more than asteriod belt ones are); and the http://cfa-www.harvard.edu/iau/lists/MPLists.html distinguishes between 'trans-Neptunian objects' (the classic EKB?), 'Centaurs' (orbit inside Neptune, e.g. Chiron), and 'scattered disk objects' (Sedna is listed as one such; it may, however, be the first discovered of a quite different kind of object).
 
  • #9
Seeing as there's no actual definition of what a planet is I'm going to vote it's a planet because it's a rather arbitrary definition anyway. Astronomy is filled with archaic things that would make more sense if we didn't use them the way they are (such as stellar magnitudes for example) so who really cares about one more?
Plus if we demoted Pluto from planethood the mnemonic "My Very Educated Mother Just Served Us Nine Pizzas" wouldn't work anymore and then where would we be? :cry:
 

1. Is Pluto still considered a planet?

No, Pluto is no longer classified as a planet. In 2006, the International Astronomical Union (IAU) redefined the criteria for what constitutes a planet and determined that Pluto did not meet these criteria. Instead, it is now classified as a "dwarf planet".

2. Why was Pluto demoted from planet status?

Pluto was demoted from planet status because it did not meet the IAU's new criteria for being considered a planet. According to the new criteria, a planet must orbit the sun, have enough mass to assume a nearly round shape, and have cleared the neighborhood around its orbit. Pluto meets the first two criteria, but it does not meet the third as its orbit overlaps with that of Neptune.

3. What is a "dwarf planet"?

A dwarf planet is a type of celestial body that orbits the sun and has enough mass to assume a nearly round shape, but does not meet the criteria to be considered a planet. Other dwarf planets in our solar system include Ceres, Eris, Haumea, and Makemake.

4. Was Pluto ever considered a planet?

Yes, Pluto was considered a planet for many years before its reclassification. It was first discovered in 1930 and was classified as the ninth planet in our solar system until 2006 when it was reclassified as a dwarf planet.

5. Can you see Pluto with the naked eye?

No, Pluto cannot be seen with the naked eye. It is too small and far away from Earth to be visible without a telescope. Even with a telescope, it appears as a small, dim dot in the sky.

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