is pluto a planet or not?

Question

people have told me many things and IDK

Answer 1

It used to be a planet but concerning new regulations on the required size of a planet, Pluto did not match this number and has had its planet title revoked.

Answer 2

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) the neighborhood of its own orbit of debris. Instead, they decided to classify it as a "dwarf planet".

There is a precedent for this. When Ceres was first discovered in 1801, it was considered to be a planet. After astronomers discovered several other objects in the same orbit, it was reclassified as an asteroid. And, in 2006, it was again reclassified as "dwarf planet" just like Pluto.

Neither Ceres nor Pluto have enough mass (gravity) to accrete all the junk from their orbits. They will be "dwarf planets" until we humans decide otherwise.

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 3

Officially, it has been re-classified as a "dwarf planet". Otherwise we would need to expand the list of planets to something like 12 or 13. This is not the first time this has happened; in the early 1800's Ceres was considered a planet for a while until astronomers started finding a bunch of smaller bodies in the same general area and re-classified Ceres and simply the largest of what we now call "asteroids".

Answer 4

I have to ask you - do you live on Pluto?

Wasn't this huge news just recently? Pluto is no longer considered a planet. Period.

Answer 5

Just recently it was voted off the planet list...

Answer: Not a planet...

Answer 6

Hi. Pluto is a dwarf planet. Always has been but we just admitted it publicly. http://en.wikipedia.org/wiki/Dwarf_planet

Answer 7

No. It doesn't fit the new definition of planet because it is too small and hasn't cleared it's orbit.

Answer 8

pluto died last year. he is no longer a planet.

Answer 9

reclassified as a moon

Answer 10

yep