On what basis Pluto was removed from our Solar System?

Answer 1

IAU Definition:
Quote:

(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) shape2 , (c) has not cleared the neighbourhood around its orbit, and (d) is not a satellite.

(3) All other objects3 except satellites orbiting the Sun shall be referred to collectively as "Small Solar-System Bodies".

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


IAU Resolution: Pluto

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.1



And its BS. First off, its filled with poor english, contradictions, and was only voted on by 300 people. It also discludes any body in another solar system from being a planet. Resolutions 5A and 6A contradict each other - and really, footnote 1 of 5A truly reveals the agenda. A few astronomers don't like Pluto being a planet - but cannot come up with the words to disclude - so the make a poor definition and footnote it with a declaration (that contradicts the definition itself)

The definition will not hold.

Answer 2

pluto has not been removed from the solar system. the international astronomical union has defined three new terms.

(1) A classical 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, and (c) has cleared the neighborhood 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, (c) has not cleared the neighborhood around its orbit, and (d) is not a satellite.

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

if a round body orbits the sun in an isolated orbit then it is a classical planet. if a round body orbits the sun and a bunch of other similar bodies with similar orbits do also then it is a dwarf planet. this does not change anything about the solar system or pluto, but it does correct the mistake of classifying pluto as a planet initially. i personally feel somewhat vindicated by this vote. i have known since i was about twelve that pluto does not have the physical and orbital characteristics that fit the pattern set by the major bodies in the solar system, and later, with the discovery of hundreds of other bodies similar to pluto, i knew this was inevitable.

Answer 3

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 also has to dominate the neighborhood around its orbit.

Pluto can not lay claim to being able to dominate the neighborhood around it because its gravitational field is just not strong enough. It is still a planet, but is now classified as a dwarf planet, along with many other objects in our solar system.

And to answer the one person who asked how much this endeavor cost? It didn't cost anything. The international astronomical society is a non-profit group of space scientists that meet every now and then to decide on standards. Much like how the IEEE decides how all the electronics in your life work.

Answer 4

From NASA:

"Here's how it all shakes out. The International Astronomical Union has decided that, to be called a planet, an object must have three traits. It must orbit the sun, be massive enough that its own gravity pulls it into a nearly round shape, and be dominant enough to clear away objects in its neighborhood.

To be admitted to the dwarf planet category, an object must have only two of those traits -- it must orbit the sun and have a nearly round shape. And no, moons don't count as dwarf planets. In addition to Pluto, Ceres and 2003 UB313, the astronomical union has a dozen potential dwarf planets on its watchlist."

So Pluto is one of many (perhaps millions) of "Pluto like object" that inhabit a part of the solar systen called "The Kuiper Belt" and Pluto is not even the largest of those objects, although it was the first to be discover. So Pluto is NOT dominant on his area.

Mike Brown, the discoverer of 2003 UB313, said:

"Pluto and 2003 UB313 are significantly smaller than the other planets. If you were to start to classify things in the solar system from scratch, with no preconceived notions about which things belong in which categories, you would likely come to only one conclusion. The four giant planets -- Jupiter, Saturn, Uranus, Neptune -- belong in one category, the four terrestrial planets -- Mercury, Venus, Earth, Mars -- belong in one category, and everything else belongs in one or maybe more categories. You wouldn't lump the largest asteroid -- Ceres -- in with the planets, you would group it with the other asteroids. Likewise you wouldn't group the largest object in the vast swarm of objects beyond Neptune (the "Kuiper belt") with anything other than the Kuiper belt. The previous nine (or ten) "planets" encompassed the group of giant planets and the group of terrestrial planets and then awkwardly ventured out into the Kuiper belt to take in one or two of the largest of those objects. Using the word in this way makes no scientific sense whatsoever."

and also said:

"I'm of course disappointed that Xena* will not be the tenth planet, but I definitely support the IAU in this difficult and courageous decision, It is scientifically the right thing to do, and is a great step forward in astronomy."

* As he (Brown) would like 2003 UB313 to be called but not its official name yet.

Answer 5

It was too small and the orbit was out of character compared to the rest of the Solar System's planets.

Answer 6

The IAU members gathered at the 2006 General Assembly agreed that a "planet" is defined as 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.

Pluto fails parts b (it is a chunky object that didn't have strong enough gravity to pull itself into a sphere) and c (it's orbit is full of other objects which are not much smaller.

Aloha

Answer 7

It was removed on the basis that a kansan discovered it, and that being the only significant scientific discovery for us kansans, i guess they thought they would be funny to get rid of it. Why do you think it was reclassified as a dwarf planet? I mean because of that i will have to deal with more wizard of oz crap!

Answer 8

well, two things are needed for an object to be defined a planet.. it revolves in a distinct orbit around the sun... and it should be large enough to have a gravitational effect on objects around it... it didn't qualify on the second front..

Answer 9

Pluto was removed because of it's small size, and the fact that it has no atmosphere.

Answer 10

Scientists say it is a dwarf planet and does not fit the criteria for planet status. I personally think it should remain a planet.