Is pluto just a moon and not a planet?

Answer 1

The International Astronomical Union decided that Pluto was no longer a planet. The reason is that while Pluto is round, orbits the sun, and has three moons, it has not cleared (via gravity) its own orbit of debris. Instead, they decided to classify it as a "dwarf planet".

See the details below.

RESOLUTION 5A
The IAU therefore resolves that "planets" and other bodies in our Solar System, except satellites, be defined into three distinct categories in the following way:

(1) A "planet" [footnote 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" 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 [footnote 2] , (c) has not cleared the neighbourhood around its orbit, and (d) is not a satellite.

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


Footnote 1: The eight "planets" are: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune.

Footnote 2: An IAU process will be established to assign borderline objects into either dwarf planet and other categories.

Footnote 3: These currently include most of the Solar System asteroids, most Trans-Neptunian Objects (TNOs), comets, and other small bodies.

RESOLUTION 6A
The IAU further resolves:

Pluto is a "dwarf planet" by the above definition and is recognized as the prototype of a new category of trans-Neptunian objects.

Answer 2

Pluto is a dwarf planet, which means that it is still a planet, just smaller and less important than the normal planets. It can't be a moon because it has a moon, Charon. Some people think they might make a double planet instead of a dwarf planet and its moon.

Answer 3

Wrong. Pluto is a dwarf planet, which means it is a planet, but it is smaller and has a less intricate role in the solar system. It is not a moon because a moon is a mass that has been pulled into another planets orbit. The gravitational pull of the sun on the mass was not as strong as that of the planet, thus the planet pulled it into its own revolution. A moon does not revolve around the sun on its own, a moon revolves around a planet.

Answer 4

http://en.wikipedia.org/wiki/Pluto

no, pluto was never a moon of neptune. neptune did capture triton. this is why triton has a retrograde orbit.


pluto does orbit the sun, is ball-shaped and is not a satellite, but it does not have an isolated orbit (a bunch of other similar bodies have similar orbits.) so it is not a planet.

i have been waiting for this since i was about ten when i learned that pluto didn't fit the pattern set by the major bodies in the solar system so it was an anomaly. it just felt "out of place". now that astronomers have found hundreds of other bodies with similar orbits, classifying "134340 pluto" as a planet is even more irrational. i feel somewhat satisfied, but i don't know how long this will drag on tho. many planetary astronomers are satisfied that the definition is rigorous enuf. i can accept that the definition is flawed, but i can not accept that "134340 pluto" is a planet.

this was the right thing to do, believe me. this does not change anything about pluto or the solar system. this just corrects the mistake of classifying pluto as a planet initially.

this same thing happened has happened before. in 1800, an astronomer found a body orbiting the sun between the orbits of mars and jupiter and thought it was a planet. astronomers finally stopped classifying them as planets after they found several other bodies with similar orbits, and no one thinks ceres, pallas, juno, and vesta are planets today.

many astronomers consider pluto and charon to be a binary system, but two small bodies orbit that system. they are called nix and hydra.

Answer 5

It is certainly a "dwarf planet." It means that it is a planet but not big one. A moon always orbits around a planet, which is not true about pluto. On the other hand, a planet revolves around su, which is true about pluto.... pluto is not so big though. It has got minor effects on our solar system.

Answer 6

Pluto is no longer a planet.Scientists went to an agreement that Pluto is a asteroid. An asteroid is like a small planet that is too small to be a planet.

Answer 7

Of course it's not a moon. If it were a moon it would be orbiting a planet and it's not.

Pluto is officially categorized as a dwarf planet. That means that it meets all the criteria of a planet (spherical shape, orbits a star directly in a near-circular pattern, not a star, etc.) except that it's gravity isn't strong enough to pull in nearby debris, known as "clearing its orbit".

Answer 8

Not a moon because it orbits the Sun and not a planet. A dwarf planet, since it is smaller than several moons.

Answer 9

Pluto is currently designated a 'dwarf planet', along with Ceres, and one other object they've found. It's not really a moon, since it's not revolving around a larger object. (It's been suggested it's really a binary system in conjunction with its moon Charon. In terms of orbital center, Charon doesn't revolve around Pluto insomuch as each revolves around the other.)

Answer 10

Well im sure it is not a moon but it is a dwarf planet. if it were a moon then it would be orbiting a planet but it isnt.