can someone please tell me why they are saying pluto is not a planet?

Answer 1

Because it is not the master of its orbit and the zone around it, as it crosses Nepture's orbit, and Neptune is the bigger planet.

The new definition states that a planet has to be the big kid on its block, which Pluto isn't.

Answer 2

I can't see the problem. Pluto is now a much more exciting object, as it is one of a growing number of discovered dwarf planets that are much more mysterious than the main planets because they do not fit the current theories for the formation of the Solar System.

Also, to leave Pluto as a planet would mean all like objects that are discovered in the future, and there may be thousands, would have to be called planets.

Then how would you remember all their names?

Answer 3

Because astronomers have decided the ancients were right when they said that the solar system consists of concentric spheres of influence. The only problem is that they did not recognize that Earth has such a sphere, too. Each of the eight planets now has its own sphere of influence - the largest object in its orbit and larger than all the rest of the objects in the orbit put together. Ceres, Xena, and Pluto do not have spheres of influence because they share the same sphere with numerous objects in an asteroid belt. The asteroid belts - Mars/Jupiter and Kuiper - can be considered spheres of influence without planets. So the Solar System has 10 spheres.

Answer 4

The main justification for Pluto no longer being a planet is its orbit. The 8 other planets all have circular orbits. Pluto's orbit is ellipitcal and it crosses the path of Neptune's orbit. There are many objects that revolve around the Sun that are not planets such as asteriods and comets. I think it mainly arises out of a suspicion that perhaps Pluto is an overgrown asteroid that happend to pull in three smaller asteroids that rotate around the planet. Also, every other planet on the other side of the asteroid belt is gaseous. Pluto is not. That in itself may very well have made its status as a planet questionable in the first place.

Answer 5

There are about 40 newly discovered objects that would fit the old notion of a planet. THAT is why pluto has been denounced to "dwarf" planet. The kuiper belt has many such objects as large as or larger than pluto. Pluto is just another one of those many objects!

Even though there are currently about 40 known objects of the size of Ceres and Pluto, many more likely exist that have just not been discovered yet.

Answer 6

I know that learning that Pluto was not considered a planet was a trip after learning it was through school. They say it's because Pluto follows its own orbit seperate from the other planets in the Solar System.

Answer 7

Yes, the first four planets are terrestial (rock) midgets and the next four planets are gaseous giants. Then comes Pluto, basically a midget snowball. Then comes the outskirts of the solar system, including the oort cloud and a lot of other things such as comets, gases and midget snowballs. We have to draw the line somewhere, why not say that the last planet is the last gas giant and anything else is "leftover junk".

Answer 8

As of yesterday Pluto is nolonger considered a planet because it doesn't have sufficent mass, and that it's orbit crosses that of Neptune. It has been deemed a Dwarf Planet along with Sedna and Xena.

Answer 9

It has an unusual orbit - not set in the way that classifies planets (i.e: does not have moons, is not in harmony with the rotation of other planets in our solar system etc.). It's also really tiny - but I don't feel this is an excuse to pick on it...

Answer 10

Because it does not meet certain criteria that had been set by the scientists to qualify as a planet