why isn't Pluto a planet?

Question

my duaghter has a project .she's seven and needs to know things about pluto .her name is lashawn .i forgot why it isn't a planet

Answer 1

It isn't large enough.

Courtesy of wikipedia:
"The debate came to a head in 2006 with an IAU resolution that created an official definition for the term "planet". According to this resolution, there are three main conditions for an object to be considered a 'planet':

1. The object must be in orbit around the Sun.
2. The object must be massive enough to be a sphere by its own gravitational force. More specifically, its own gravity should pull it into a shape of hydrostatic equilibrium.
3. It must have cleared the neighbourhood around its orbit.[97]

Pluto fails to meet the third condition, since its mass was only 0.07 times that of the mass of the other objects in its orbit (Earth's mass, by contrast, is 1.7 million times the remaining mass in its own orbit).[98][99] The IAU further resolved that Pluto be classified in the simultaneously created dwarf planet category, and that it act as prototype for a yet-to-be-named category of trans-Neptunian objects, in which it would be separately, but concurrently, classified."

Answer 2

Until 2006, there wasn't any official definition for a planet. Then a group of scientists called the International Astronomical Union created one.

Pluto isn't a planet because it hasn't cleared its orbit of planetesimals. That means its gravity isn't strong enough clear out of the random rocks in its orbit. Officially, Pluto is a dwarf planet. There are two other dwarf planets: Eris, a small Pluto-like object way out at the end of the solar system, and Ceres, a part of the asteroid belt.

Answer 3

It's not just that it's too small. It's orbit is not in the same plane as all the other planets and it also comes inside the orbit of Neptune at one point in it's orbit.

Pluto is probably a captured body like an asteroid.

Answer 4

Pluto was demoted as it isn't large enough and it's orbit is in question. There have been new planets added but are not taught in the school system as of yet. Good luck with your project.

Answer 5

The scientists were studying Pluto more carefully, and decided it was too small to be a planet,. So they think it is a moon that got off of another planets orbit.

Answer 6

Pluto is a Kuiper Belt Object. (KBO). The Kuiper belt is like another asteroid belt, but lays after Neptune instead of between Jupiter and Saturn.

Answer 7

its mainly ice aswell so they cant decide if this constitutes a planet or not

Answer 8

they say its to small to be a planet

Answer 9

THE FOLLOWING LINK MAY BE OF HELP IN UNDERSTANDING.

Answer 10

i think the first answer helps her the most! he said what i wantd to say.....♥