Is Pluto still classed as a planet ?

Question

Or has it been downgraded to a minor planet the same as Xenia ?

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

It is a planet, but instead of being considered an official planet, the International Astronomical Union downsized it to a dwarf planet on August 24, 2006. They now have new rules to be qualified as a planet. They are:

One) It must orbit the Sun.

Two) It must be big enough for gravity to squash it into a round ball

Three) It must have cleared other things out of the way in it's orbital neighborhood.

Here is the descirption for a dwarf planet


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.


Hope this helps.

Answer 3

It is actually a "dwarf" planet. It has also received a number as a "minor" planet (134340).

It is no longer listed as a "planet" (implying a "major" planet).

Many people still consider it a planet. But the International Astronomical Union made the decision earlier, in 2006.

Answer 4

Last summer it was downgraded, not to minor planet status, but to asteroid status. I believe that the principal criterion for the ruling was that it's orbit a) was tilted relative to the orbital plane shared by the other planets and b) sometimes brought it closer to the sun than Neptune.

Answer 5

As of now, Pluto is considered a "dwarf planet". From what I read, on August 24th, the IAU decided on a new definition of "planet" which does not include Pluto. Pluto is now classified as a "dwarf planet", a class distict from "planet".

Answer 6

No.. we are down to 8 planets and 3 minor planets... damn... 40 yrs of schooling just went down the drain

Answer 7

Pluto was downgraded in the USA. Not sure about whether the Europeans have downgraded it yet.

Answer 8

Pluto is officially now classified as a 'dwarf planet'

Answer 9

NO! It is considered a meteorite because it's too small and it has a different orbit than the other planets on our Solar System!

Answer 10

Neil deGrasse Tyson