Why was Pluto discredited as a planet?

Question

Why was Pluto discredited as a planet?

Answer 1

bcuz with new discoveries it was clear that pluto was fundamentally different. they could either redefine "planet", or redefine "pluto". they chose the latter.

scince changes all the time. new facts and new ideas are a fact of life.

Answer 2

Too small... b******s

Answer 3

Because of this guy

http://www.youtube.com/watch?v=Wh9QNEoJZ...

Answer 4

The semi-short answer is that in 2006, the IAU issued a new definition of planet which included the requirement that it had to have cleared the area around it. Pluto was demoted to Dwarf Planet. Eris (also in the Kuiper Belt), and Ceres (in the Asteroid Belt) were added to this classification. There was a lot of resistance to the demotion of Pluto, and in June, 2008, The new name Plutoid was decided on to refer to those (formerly Dwarf Planets) that were outside Neptunes orbit as Plutoids. Ceres (in the Asteroid Belt) was not included. It had been previously classified as an asteroid, then a dwarf planet, and the IAU, considering it a one-of-a-kind object determined to not have a dwarf planet classification. Now, Pluto and Eris are plutoids, while Ceres remains a dwarf planet. So it is a dwarf planet, but has no classification.

"Aug 24, 2006, Prague

(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" 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.

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

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

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."

"Pluto-like objects to be called 'plutoids'

18:56 11 June 2008

NewScientist.com news service

From now on Pluto won't just be any dwarf planet, it will be a 'plutoid.'

The International Astronomical Union (IAU) announced the name today after two years of deliberation. The new classification will be used to refer to bright dwarf planets that spend the bulk of their time outside Neptune's orbit.

So far, Pluto and its larger neighbour, Eris, are the only named objects that qualify as plutoids, but more dwarf planets are expected to follow.

In 2006, IAU members voted to demote Pluto from planet to 'dwarf planet', defined as an object large enough for gravity to make round, but not big enough to clear out its orbit.

At the same time, they also voted to come up with an alternate name for similar, Pluto-like objects. The name 'plutoid' was chosen partly in deference to Pluto's fallen glory.

"In the end, we ended up with something Pluto-like, and I don't think we could have done better," IAU general secretary Karel A van der Hucht, told New Scientist.

But the name is not universally loved. "It sounds like 'hemorrhoid' and it sounds like 'asteroid', and of course these objects are planets and not asteroids," says planetary scientist Alan Stern of the University Space Research Association in Maryland, US.

The term 'plutoid' will not apply to all dwarf planets. Ceres, for example, which sits in the asteroid belt between Mars and

Jupiter, will not be a part of this category.

'Plutoids' must also be a minimum brightness, a requirement that will exclude dozens of dwarf planet candidates that have been spotted in the Kuiper belt, a ring of icy objects beyond Neptune, says Michael Brown of Caltech in Pasadena, US.

"That's an odd definition," Brown told New Scientist. "It makes objects of exactly the same size 'plutoids' or 'not plutoids' "

"Here's the official new definition:

"Plutoids are celestial bodies in orbit around the sun at a distance greater than that of Neptune that have sufficient mass for their self-gravity to overcome rigid body forces so that they assume a hydrostatic equilibrium (near-spherical) shape, and that have not cleared the neighborhood around their orbit."

In short: small round things beyond Neptune that orbit the sun and have lots of rocky neighbors.

The two known and named plutoids are Pluto and Eris, the IAU stated. The organization expects more plutoids will be found.

The dwarf planet Ceres (which used to be called an asteroid, and before that was called a planet!) is not a plutoid as it is located in the asteroid belt between Mars and Jupiter, according to the IAU. Current scientific knowledge lends credence to the belief that Ceres is the only object of its kind, the IAU stated. Therefore, a separate category of Ceres-like dwarf planets will not be proposed at this time, the reasoning goes."

Answer 5

History repeats itself.

In 1850, there were 12 planets:

Mercury, Venus, Earth, Mars, Ceres, Pallas, Juno, Vesta, Jupiter, Saturn, Uranus and Neptune (discovered in 1846).

Then telescopes got better and, starting in the early 1860s, people were discovering all kinds of new planets between Mars and Jupiter.  

It was decided that all these smaller objects, all on similar orbits, would form a new class: the minor planets.  They were also called "asteroids" because they looks like stars (points of light) instead of planets (disks) in telescopes.

Good thing too, otherwise we'd have to learn the names of around a quarter million planets by now.

Fast Forward to the early 2000s.  Newer telescopes with automated software to find new "stuff".  We are discovering minor planets by the dozens every day.  We are suddenly beginning to discover a handful of objects like Pluto, on orbits similar to Pluto.

Do we start having more planets until we get fed up when we get to 100?  Or do we use the same solution now as we did in the 19th century.

They picked B.  Showing that they have a sense of history.

The Kuyper belt may contain hundreds (even thousands) of objects like Pluto, which will be discovered with the next generation of automated search telescopes.  The Kuyper belt could have 100 times the mass of the asteroid belt.  We have found hundreds of thousands of minor planets; we should expect to find a million objects in the Kuyper belt.

Then we'll get even better telescopes and get to the Oort cloud.  The asteroid belt and Kuyper belt are very tiny, compare to it.

And there may still be a "real" planet (or even two) waiting to be discovered way out there.

Answer 6

Well there was never a real definition for a planet. So when scientists made one Pluto didn't fit the definition. Now Pluto is considered a dwarf planet along with two others.

Answer 7

My professor had friends on the committee that decided this. Apparently,they didn't want Pluto considered a planet because then they'd be forced to classify several planetoids planets as well, since they were larger than Pluto. They'd rather drop one than add several. I heard it mostly the older scientist that voted for this. Conservatism of old age. (Unwillingness to change.) "We can't have too many planets!" The younger ones had no problem with adding new planets.

Answer 8

The scientist say that Pluto is too small and is just a ball of ice. Unfortunately for them, they are idiots, 9 planets are always better then 8. Wait...How mant planets do we have now?

Answer 9

Because the group of scientists, in charge, decided that they wanted to really have a true "definition" for the word planet.  So they created a meaning for it.  Therefore, sense Pluto doesn't now fall into that definition due to the fact that it is surrounded by many other things and planetesimals.  It is now considered a "dwarf Planet" and there are many others out there in space (and even one asteroid)!  One dwarf planet even found by an astronomer named Mike Brown, hence beginning the controversy.

Answer 10

Because Disney did not accept the trademark contract from NASA.  DOGS RULE!

http://www.mines.edu/research/k12-partne...

Answer 11

cause its orbit is overlapping with Neptune's so it is really influenced by Neptune gravity...

Answer 12

it is considered as a moon detached from the gravitational pull of nearby planets

Answer 13

Because scientists have no perspective as to what history means.

Answer 14

It is too small. Also, there are other celestial bodies that are just about as far as pluto or slightly further that are the same size or even larger. It doesn't even dominate it's moon like other planets do.

Answer 15

they decided to make a new category called dwarf planets and pluto fits in.

Answer 16

i think because it is too small, they like decided its just a rock or something...

Answer 17

Pluto is too small to be a planet and it has a different orbit

Answer 18

scientists all over the world decided that the size of pluto was not big enough to be categorized as a planet. It is now considered a 'dwarf' planet. there are a few 'objects' as the scientists call them, past pluto and they are doing many studies to see if they can be categorized as planets in our solar system

Answer 19

When the International Astronomical Union finally decided to define "planet" they defined it as having 3 necessary characteristics:

1. Has hydrostatic equilibrium (in other words, "is round.")

2. Is not a Moon (doesnlt orbit another body)

3. Has "cleared" its orbital neighborhood (its gravity has pushed any other nearby bodies out of the area.)

Pluto fits the first two of these criteria, but not the third.  Pluto's orbital neighborhood has dozens of other objects in it.

So they decided that an object which meats the first two criteria, but not the third, is a "dwarf planet."

There are now 4 known and named dwarf planets.  Ceres (an asteroid) in the main asteroid belt,  and Pluto, Eris, and Makemake (just recently named) in the outer kuiper belt (these last three are also called "Plutinos."

Answer 20

because is the smalles of the planets, and the one who is the most far away, so they desided to discredited as a planet/

in my personal opinion, they have nothing better to do lol

Answer 21

I think they discovered a bunch of other "non-planets" like pluto.  They were all just big balls of ice like pluto.

Answer 22

To small and it doesn't fallow the same orbit shape as the other planets

Answer 23

Pluto was taken out of the planet category because one and everyone here has said it Pluto is very small. That isn't the only reason, the other reason was because its orbit is so elliptical and not even close to the same plane that the other planets are basically on that it had more characteristics of a comet than a planet. It was still to big to be called a comet so i guess they called it a dwarf planet.