why is pluto no longer a planet?

Answer 1

Well for starters, Pluto is just too small. In the neighborhood where Pluto lives? Planets are supposed to be huge. The Jovian planets, Jupiter, Saturn, Uranus and Neptune are 20 to 300 times the size of the Earth, and Pluto is really small compared to the Earth, smaller than our Moon. Kind of stands out.

And Pluto is not made out the same material as the Jovians. The large planets are mostly gigantic spheres of gas, mostly hydrogen and helium. Likely there are no solid surfaces, only denser and denser gas all the way in. Pluto is a small solid world of methane, water, carbon dioxide and ammonia ices, maybe a little rock and with a just hint of atmosphere (that freezes out and falls as snow in her "winter").

And third, Pluto's orbit is the most eccentric (oval shaped) and the most tilted to the plane that the rest of the planets orbit in. Also, Pluto is locked in a resonance with Neptune's orbit and comes closer to the sun than Neptune sometimes.

There were theories that Pluto was a lost moon of Neptune but that was before we discovered she a has one large moon (Charon) half her size (pretty much, this system is a double planet) and recently two other teeny-tiney moons.

Pluto seems like she cant be an ejected moon-she must have formed on her own and seems to be part of an entire army of small icey-dwarf objects that circle just outside Neptune's orbit in what is known as the Kuiper belt. We have no idea of how many or how large these objects may be. NOT "planets" proper, hence the new term "dwarf planet" where Pluto is king.

BUT I still think Pluto should be called a planet because of historical reasons (discovered by an American, financed by Percival Lowell, Tombaugh's life story, etc).

Answer 2

The Bible doesn't even mention other planets. Until very recently, there had never been an attepmt to give a solid definition as to what a planet is. The only thing that was required to be a planet was that it was a celestial body that orbited a star or individual system of stars (like binary stars) The problem is that all the junk in the asteriod belt would qualify as planets, then, as well as arguably moons that orbit planets which orbit stars. Various qualifications were proposed. Ultimately, the one that was widely accepted (though not completely) that disqualified Pluto was that it must orbit around a star and nothing else. Pluto's moon, Charon, is close enough in size to Pluto itself that the moon does not orbit around Pluto. Instead, both of them orbit around a point in space between them (closer to Pluto, but not anywhere inside Pluto). As such, Pluto and Charon both orbit that point which orbits the Sun, rather than Pluto itself orbitting the Sun.

Answer 3

The International Astronomy Union defined the term "planet" scientifically. Pluto does not have the necessary dimensions and characteristics to be a planet; however it is to big to be an asteroid and has a natural satellite too.

So, Pluto becomes a dwarf planet, along other Trans-Neptunian objects like Eris (another dwarf planet and bigger than Pluto) and Sedna.

Answer 4

The planets must be able to clear the area around it by its own gravity. This includes all asteroids, comets and other things. A bunch of scientists decided that Pluto does not do this and therefore it is not a planet any more.

Answer 5

Because a small group of scientists decided to speak for every scientist on earth and every human on earth to demote Pluto to dwarf planet status. There's no way that definition isn't going to be overturned during the next international meeting of astronomers.
The definition that they made up that says that a planet has to "clear its orbit" is ludicrous. Think about it: Pluto's orbit intersects Neptune, so that means that *Neptune hasn't cleared its orbit*. I know they're talking about space debris (asteroids) but really, their wording is just stupid.

Answer 6

Scientists decided that the total mass was not large enough to be considered a planet. There are asteroids and comets that are larger. I miss planet Pluto. It must be depressed now. Its been downsized.

Answer 7

NASA has set new standards for planets and Pluto is simply too small.

RIP PLUTO.

Answer 8

Some scientists got together with accountants and lawyers and adopted a silly formula and Pluto didn't fit the specs.

Answer 9

Because people cant just leave be what has been for 50 years.... Why take away the title now? Its a stinkin planet ok?!!

Answer 10

Because they have more evedence showing it is an asteroid stuck in the sun's orbit then eveidence that it is a planet.