Is Pluto the planet or is Charon?

RAT

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Neither are planets. Pluto is now considered a dwarf planet and Charon is its moon.(If you can call it that since Pluto isn't a real planet.)
Pluto is a KBO which stands for Kuiper belt object. There are probably hundreds of objects just like Pluto out in the Kuiper Belt.

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Neither are planets. Pluto is now considered a dwarf planet and Charon is its moon.(If you can call it that since Pluto isn't a real planet.)
Pluto is a KBO which stands for Kuiper belt object. There are probably hundreds of objects just like Pluto out in the Kuiper Belt.

THEN MAYBE WE HAVE HUNDREDS OF PLANETS?????

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Neither are planets. Pluto is now considered a dwarf planet and Charon is its moon.(If you can call it that since Pluto isn't a real planet.)
Pluto is a KBO which stands for Kuiper belt object. There are probably hundreds of objects just like Pluto out in the Kuiper Belt.

THEN MAYBE WE HAVE HUNDREDS OF PLANETS?????

I ask the age old Question in defiance of the experts!!!!

What is a planet???

RAT

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I agree with the new definition of a planet set by the IAU a few weeks ago.

(1) A "planet" [1] is a celestial body that: (a) is in orbit around the Sun, (b) has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape, and (c) has cleared the neighbourhood around its orbit.

(2) A "dwarf planet" or a planetoid is a celestial body that: (a) is in orbit around the Sun, (b) has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape [2], (c) has not cleared the neighbourhood around its orbit, and (d) is not a satellite [of a planet].

(3) All other objects [3] orbiting the Sun shall be referred to collectively as "Small Solar System Bodies".

Footnotes:

[1] The eight planets are: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune.
[2] An IAU process will be established to assign borderline objects into either "dwarf planet" and other categories.
[3] These currently include most of the Solar System asteroids, most Trans-Neptunian Objects (TNOs), comets, and other small bodies.

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I agree with the new definition of a planet set by the IAU a few weeks ago.

(1) A "planet" [1] is a celestial body that: (a) is in orbit around the Sun, (b) has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape, and (c) has cleared the neighbourhood around its orbit.

(2) A "dwarf planet" or a planetoid is a celestial body that: (a) is in orbit around the Sun, (b) has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape [2], (c) has not cleared the neighbourhood around its orbit, and (d) is not a satellite [of a planet].

(3) All other objects [3] orbiting the Sun shall be referred to collectively as "Small Solar System Bodies".

Footnotes:

[1] The eight planets are: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune.
[2] An IAU process will be established to assign borderline objects into either "dwarf planet" and other categories.
[3] These currently include most of the Solar System asteroids, most Trans-Neptunian Objects (TNOs), comets, and other small bodies.

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I agree with the new definition of a planet set by the IAU a few weeks ago.

(1) A "planet" [1] is a celestial body that: (a) is in orbit around the Sun, (b) has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape, and (c) has cleared the neighbourhood around its orbit.

(2) A "dwarf planet" or a planetoid is a celestial body that: (a) is in orbit around the Sun, (b) has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape [2], (c) has not cleared the neighbourhood around its orbit, and (d) is not a satellite [of a planet].

(3) All other objects [3] orbiting the Sun shall be referred to collectively as "Small Solar System Bodies".

Footnotes:

[1] The eight planets are: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune.
[2] An IAU process will be established to assign borderline objects into either "dwarf planet" and other categories.
[3] These currently include most of the Solar System asteroids, most Trans-Neptunian Objects (TNOs), comets, and other small bodies.

I reject your Reality and substuitute my own!

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(2) A "dwarf planet" or a planetoid is a celestial body that: (a) is in orbit around the Sun, (b) has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape [2], (c) has not cleared the neighbourhood around its orbit, and (d) is not a satellite [of a planet].

...all of which makes Mars a dwarf planet for the same reason as Pluto -- two gnarly little moonlets. Now about all those rocks orbiting Jupiter...

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No, Mars IS a planet because its orbit does not interfere with other planets' orbits, unlike Pluto's which of course interferes with Neptune's orbit.

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No, Mars IS a planet because its orbit does not interfere with other planets' orbits, unlike Pluto's which of course interferes with Neptune's orbit.

The planets (oh, and Pluto) all interfere with each other to the extent that the astronomical unit (AU), the distance between the centers of the sun and Earth, has no constant value due to chaotic gravitational interactions. It has to be computed every time a precise value is needed.

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But still do you see my point

Mars is not a planetoid because nothing is interfering its orbit around the sun; its orbit is its own orbit, unlike Pluto, which shares its orbit with Neptune temporarily and also with some KBOs. Also, the other thing about Pluto is that Pluto and Charon actually orbit around each other; Charon is NOT a satellite of Pluto.

EDIT: And the fact that Charon and Pluto orbit around each other is probably a big reason why Pluto should be considered a KBO and not a planet. It shouldn't even be considered a planetoid for that reason

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I see your point, but my preference is more planets rather than fewer. If anything should be eliminated from planet status it's the gas giants. They have nothing in common with the prototypical planet, Earth, and really deserve their own category between planets (with landable surfaces observable in visible light or radar) and brown dwarfs (which begin deuterium fusion at about 19 Jupiter masses). With that designation, satellites of gas giants that are massive enough to collapse into spheroids then become planets. Which suits me better -- Europa is certainly more Earth-like than Jupiter.

BTW, all things in orbit orbit each other. Earth and the moon orbit each other as well, but the center of gravity is inside the earth due to our hugely massive core. Extrasolar planets and their stars orbit each other, producing the stars' wobbles that allow us to detect the planets.

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Hey, listen to this:

Don't say Pluto, say 134340

The enigmatic, icy world spotted in 1930 has been given the official monicker of 134340 Pluto and lumped among 136,562 asteroids and other small bodies by the Minor Planet Center (MPC), part of the Paris-headquartered International Astronomical Union (IAU).

Pluto's satellites, Charon, Nix and Hydra, have been numbered 134340 I, 134340 II and 134340 III respectively under the latest minor planet list, compiled on September 7.

wow, this is shocking....

Greetings

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My photography world

I found your classification of Earth as a "prototypical" planet a little simplistic. What makes Earth more qualified as a planet than Jupiter or Uranus for example? Your definition seems more like that of the rocky "terrestrial" planets: Mercury, Venus, Earth, and Mars, which do have "landable" surfaces. There are many moons of Jupiter, Saturn, as well as Uranus and Neptune that have landable surfaces as well, as well as out own moon, yet they are not planets.

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Wow what a hot topic!!

Why can't Pluto and Charon be considered a dual core planet???

Think about it combined they become unique!! in our solar system any way!

Together i am sure there orbit is more stable and they can clear the space junk in there path!!!

I say we call the New Dual Core planet PlutoCharon, PlutoCharon!

All hail PlutoCharon!!!!!

RAT

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PlutoCharon,

The first Dual core planet!!!!!

ROCK ON!

RAT

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Now if Charon orbited closer to Pluto wouldn't the center of gravity of the system be inside Pluto? Then would Charon be a satellite of Pluto?

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Is Pluto the planet or is Charon?

RAT

It is a ball of rock and ice that orbits the Sun. Its been orbiting the Sun long before we silly humans debated on what definition to give it and will continue to do so long after we are gone...

Dual Core Planets!!!!

That is the next step!

RAT

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LOL

We can have a dual core duel.

In a few months we will have a quad core duel. Doesn't have the same ring though.

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