Why isn't Pluto a planet?

Question

Why isn't Pluto a planet?-- I'm infuriated.

Answer 1

The "experts" say it's a star. Poor Pluto, now he's out in the doghouse.

Answer 2

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

on 24 august 2006, the international astronomical union reclassified pluto.

pluto does orbit the sun, is ball-shaped, does not have an isolated orbit (a bunch of other similar bodies have similar orbits.), and is not a satellite 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 between the orbits of mars and jupiter and thought it was a planet. astronomers soon found several others and finally stopped classifying them as planets. no on 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.

incidentally, "134340 pluto" was never a moon of neptune. neptune did capture triton. this is why triton has a retrograde orbit

Answer 3

Because if they left it a planet, then they would have had to make it's moon charon a planet plus hundreds and hundreds of more things. They made new rules for what can be a planet and Pluto didn't make the big enough part of it. It is now a dwarf planet. I was very mad especially because not even a 4th of all the scientists in the world got to vote on the new rules!!!!

Answer 4

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 5

Pluto isn't a planet because they say it is to small.

Answer 6

under the new rules, Pluto is too small to be considered a planet.

Answer 7

I believe because it is too small and it has a random orbit, meaning its orbit is not a set pattern like earth or the rest of the planets

Answer 8

Because the IAU considered it a "dwarf" planet. Along with other similar objects.

Answer 9

Pluto's a dog.

Answer 10

Its to small