Why is Pluto no longer a planet?

Answer 1

Pluto is no longer a planet because it doesn't fit the "definition" of a planet.
Also, Pluto was denounced from pllanet status because
1)it is very small
2)it orbits its moon while its moon orbits it
3)many "exoplanets" like Pluto have been found and we cannot make them all be planets

Answer 2

the international astronomical union voted on 24 august 2006 to adopt the following definitions of "planet", "dwarf planet", and "small solar system body" so pluto is not a planet. this does not change anything about the solar system or pluto. it just corrects the mistake of classifying pluto as a planet initially. some consider pluto and charon to be a binary system, but two small bodies orbit this system. they are called nix and hydra.

http://www.iau.org/fileadmin/content/pdfs/Resolution_GA26-5-6.pdf

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

this same thing has happened before. beginning in 1800, astronomers found a few bodies orbiting between the orbits of mars and jupiter, and they finally stopped calling them planets after several discoveries. astronomers then added numerals to the names, and pluto recently got its numeral. 150 years from now, no one will think of "134340 pluto" as a planet. very few will even know we classified it as a planet. "1 ceres" and "136199 eris" are other dwarf planets.

i have been waiting for this since i was about twelve. i feel somewhat satisfied. i knew that pluto didn't fit the pattern set by the major bodies in the solar system so it was an anomaly. it just felt illogical and "out of place". this was the right thing to do, believe me. i don't understand why so many are having such a problem with this.

i don't know how long this will drag on tho. many planetary scientists are not satisfied that the definition is rigorous

Answer 3

Only one answer tries to explain WHY the definition of "planet" was changed, and even that wasn't completely correct.

A number of bodies of comparable size to Pluto have been found in similar sized or shaped orbits. There is reason to believe there may be dozens of them. If Pluto is to be described as a planet, the new discoveries would have to be as well.

Men with beards were worried that this would create untidiness and confusion among the Great Unwashed and turn them off astronomy. So rather than have 50 planets that schoolchildren would need to remember, they put the fix in which meant that Pluto didn't fit the definition of the word "planet".

Pluto and I have one thing in common; we don't care.

Answer 4

That's a question my elementary kiddos have been bugging me about. I haven't had the hear to tell them that a very small group of "scientists" made the decision, based on a few criteria...such as...

1. Pluto and its two plus moons revolve around a central point between them all, as opposed to the moon which revolves around the Earth's center of gravity.

2. Pluto is more moonlike in size than a "normal planet" is.

3. Related to that, a "normal planet" should, in the opinion of these scientists, be able to vacuum away any objects in their path. If you look at Pluto's orbit, it's canted upwards from the orbital plane, AND it spends part of its year INSIDE the orbit of Neptune. Obviously it has been unable to vacuum away Neptune, and therefore it isn't a planet (but what about Neptune? It hasn't been able to do the same to Pluto. Does that mean IT isn't a planet, either???)

Me, personally? It's a planet, darnit! Always has been. Besides, I'm having trouble coming up with an alternate MNEMONIC to "My Very Educated Mother Just Showed Us Nine Planets" to help the kiddos remember the order. Perhaps "My Very Educated Mother Just Showed Us NOT PLUTO" might work. Dunno.

We'll see what happens when "New Horizons" gets there and starts taking pictures. That's the nice thing about science...new discoveries often re-seat one's thinking about th ings!

Ciao

Answer 5

According to the new definition, a full-fledged planet is an object that orbits the sun and is large enough to have become round due to the force of its own gravity. In addition, a planet has to dominate the neighborhood around its orbit.

Pluto has been demoted because it does not dominate its neighborhood. Charon, its large "moon," is only about half the size of Pluto, while all the true planets are far larger than their moons.

In addition, bodies that dominate their neighborhoods, "sweep up" asteroids, comets, and other debris, clearing a path along their orbits. By contrast, Pluto's orbit is somewhat untidy.

Answer 6

Quite simply put: Pluto is not a planet do to the fact that is too small and does not meet the criteria of the new definiton of a planet set forth by the IAU and its infinite??? wisdom.

Answer 7

It is too small. When it was discovered there was no telescope good enough to show its size, so it was just estimated to be as big as Mars based on its apparent brightness and its assumed dark surface, New telescopes show that is has a bright surface and is smaller than the Moon. So they reclassified it as a "dwarf planet". The word "dwarf" is to placate the people who don't want it to be a planet (like me) and the word "planet" is to placate the people who do want it to still be a planet.

Answer 8

scientists discovered pluto is not a planet its so far and its just ice its no planet cuz of the temperatures so far in outerspace there was no way a planet so far would be a planet so its an ice block so they removed it from the solar sstem

Answer 9

in laymen terms, its too small. scientists changed the criteria for what makes a planet and it turns out that PLUTO didn't fit that new criteria.

the end.

=D

Answer 10

NASA made up a new planetary guideline and pluto doesnt fit into it.