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In reply to the discussion: In the motions of distant solar system objects, astronomers find hints of Planet Nine [View all]Warren DeMontague
(80,708 posts)13. Well, that's the whole point. If Pluto is categorized as a "planet", we have thousands of planets
Which is why categorizing such objects as dwarf planets or Kuiper Belt Objects makes more sense, because none of them fall into the same broad category as the 8 major planets.
The definition worked out by NDGT and the IAU in the 2006 works just fine:
https://en.wikipedia.org/wiki/IAU_definition_of_planet
IAU definition of planet
From Wikipedia, the free encyclopedia
This article is about the formal definition established in 2006. For prior usage, see Definition of planet.
Euler diagram showing the types of bodies in the Solar System.
The definition of planet set in Prague, Czech Republic in August 2006 by the International Astronomical Union (IAU) states that, in the Solar System, a planet is a celestial body which:
is in orbit around the Sun,
has sufficient mass to assume hydrostatic equilibrium (a nearly round shape), and
has "cleared the neighborhood" around its orbit.
A non-satellite body fulfilling only the first two of these criteria is classified as a "dwarf planet". According to the IAU, "planets and dwarf planets are two distinct classes of objects". A non-satellite body fulfilling only the first criterion is termed a "small Solar System body" (SSSB). Initial drafts planned to include dwarf planets as a subcategory of planets, but because this could have led to the addition of several dozens of planets into the Solar System, this draft was eventually dropped. The definition was a controversial one, and has drawn both support and criticism from different astronomers, but has remained in use.
According to this definition, there are eight known planets in the Solar System. The definition distinguishes planets from smaller bodies and is not useful outside the Solar System, where smaller bodies cannot be found yet.
From Wikipedia, the free encyclopedia
This article is about the formal definition established in 2006. For prior usage, see Definition of planet.
Euler diagram showing the types of bodies in the Solar System.
The definition of planet set in Prague, Czech Republic in August 2006 by the International Astronomical Union (IAU) states that, in the Solar System, a planet is a celestial body which:
is in orbit around the Sun,
has sufficient mass to assume hydrostatic equilibrium (a nearly round shape), and
has "cleared the neighborhood" around its orbit.
A non-satellite body fulfilling only the first two of these criteria is classified as a "dwarf planet". According to the IAU, "planets and dwarf planets are two distinct classes of objects". A non-satellite body fulfilling only the first criterion is termed a "small Solar System body" (SSSB). Initial drafts planned to include dwarf planets as a subcategory of planets, but because this could have led to the addition of several dozens of planets into the Solar System, this draft was eventually dropped. The definition was a controversial one, and has drawn both support and criticism from different astronomers, but has remained in use.
According to this definition, there are eight known planets in the Solar System. The definition distinguishes planets from smaller bodies and is not useful outside the Solar System, where smaller bodies cannot be found yet.
it's only a "dick measuring contest" for people who have thrown unreasonable emotional or sentimental attachments onto this topic.
Also, you are incorrect. We KNOW Eris is at least as massive an object as Pluto. This is not some speculation. Like Pluto, Eris also has at least one moon.
https://en.wikipedia.org/wiki/Eris_(dwarf_planet)
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In the motions of distant solar system objects, astronomers find hints of Planet Nine [View all]
Zorro
Oct 2016
OP
No, giving Pluto some sort of special status just because that's what people learned in school
Warren DeMontague
Oct 2016
#10
This issue left science behind and devolved into a dick measuring contest a long time ago
Sen. Walter Sobchak
Oct 2016
#12
Well, that's the whole point. If Pluto is categorized as a "planet", we have thousands of planets
Warren DeMontague
Oct 2016
#13
Well if you have better observations than Hubble's please share them with everyone
Sen. Walter Sobchak
Oct 2016
#17
Im sure Mike Brown would be able to explain in detail why our knowledge of Eris's mass etc
Warren DeMontague
Oct 2016
#18
Until pretty recently, Pluto was "just a few barely observed pixels", too
Warren DeMontague
Oct 2016
#20
it is true that until 2006, "Planet" had no commonly accepted definition.
Warren DeMontague
Oct 2016
#22
If he finds the long hypothesized Planet X I don't doubt that is true.
Sen. Walter Sobchak
Nov 2016
#23
The only person who was talking down the discovery of Eris was Mike Brown himself
Sen. Walter Sobchak
Nov 2016
#29
I know! Let's send our greatest Astronaut there to explore: Donald Trump!
lindysalsagal
Nov 2016
#26