Why is the confusion of the status of pluto as a planet ?

Question

I have been reading news paper reports about the Pluto's status of a planet is being questioned, what is the reason why ? I know Pluto Revolves around Sun, and is this not sufficient for it to be a planet ?

Answer 1

Because Pluto doesnt have enough mass to have its own gravity...
it is not able to control the other bodies in its viscinity...
neptune is the king in that part of the universe and neptune even has an effect on Pluto's orbit

Answer 2

I know that there is a debate on what to CALL four bodies that circle the sun, Sol. Three of them we've known about for a while.

Pluto has been considered a planet. Ceres has been considered an asteroid. Charon has been considered a moon. "Xena" was recently discovered. This is what has led to the discussion on what the should be the definition of planet.

Here's mine.

I would say that the following are minimum characteristics of planets. 1 & 2 below are arbitrary, you may prefer other variables.

1. Minimum Mass. 10^20 Kg. (about 1/100th the mass of Pluto).

2. Minimum Diameter. 1,500 Km (about 900 miles)

3. Orbit. Must be in orbit around a sun, and not a planet (therefore, Luna is not a planet, even though it's larger than Pluto). More on this in barycenter below.

4. Distance from sun. Not relevant, as long as it is clearly in orbit around the sun. Therefore, a massive sun may have planets dozen's of light-years away.

5. Is not itself a sun. That would be a binary or higher system.

6. Must not be in interstellar space, not associated with a sun or suns.

7. Not in a field of other bodies with the same approximate orbit. That would leave out anything in the Asteroid Belt and Oort Cloud.

So, I say that Pluto is a planet.

Now, how about "Xena" (aka, 2003 UB313)? To Hades (Greek God of the underworld) with conventions for naming planets. Xena is perfect. And Gabrielle for the moon. If they can name a comet "Hale-Bopp" why not a planet after the Warrior Princess.

Now, I disagree with Charon and Ceres getting a promotion. One shares an orbital field with thousands of smaller objects that have more mass in total that Ceres.The other circles a planet, it's a moon.

If Charon is a planet, then what about Luna and some moons of Jupiter and Saturn?

Some have suggested that a moon must have an orbit whose barycenter is inside a planet. It's an interesting argument, but it depends on the density of the planet involved. That is why Charon is under consideration. Its barycenter with Pluto is outside of Pluto, and therefore, under this definition, Pluto and Charon would make up a binary planetary system within the solar system.

I'm not quite convinced on this one. If Pluto's mean density were that of Saturn's, but the mass stayed the same as Pluto's, the barycenter would be inside of Pluto. Thus, Charon's status would depend on Pluto's physical characteristics. It doesn't make sense to me to call Charon a planet in one case and a moon in the other.

Answer 3

Pluto is relatively small when compared with other objects that also revolves around the Sun. If Pluto is included, then there is no good reasons not to include those other objects. Some of these objects are asteriods (for example Ceres) which are also round in shape. Charon, Pluto's moon, may be considered as another planet. There is another object beyond Pluto, 2003 UB313 (Xena) may also be included as a planet.

Pluto and Charon are considered Twin Planets, they move around each other and both circle the Sun. Charon is argued to be not a moon of Pluto as the system's centre of mass lies outside Pluto's orbit.

Answer 4

I'm all for a new classification (asteroids, comets, planets, planetoids etc) of objects orbiting around the sun. So far we have planets which are roughly grouped into rocky earth type, and gas giants. Pluto doesn't fit into either of those categories because of its smallness and icy composition. It also doesn't fit the description of a comet even though it's chemical composition is similar (Pluto doesn't approach the sun or have a tail). So why not have the new grouping of objects called plutons? I think that's the best solution presented so far. So maybe Pluto won't be classified as a planet anymore.. At least it has the honor of being the first pluton, after which all the rest of it's kin are categorized into that group.

Answer 5

It is very small, smaller than the earth's moon. Small bodies that revolve around the sun are called asteroids, not planets. So the issue is: is Pluto big enough to be called a planet? And that, of course, depends on the definition of what a planet is. By the definition proposed by the IAU, Pluto qualifies -- barely.

Answer 6

Cos a lot of **** floats around the sun. Are we going to call all the asteroids planets too? What about comets? They orbit around the sun.

Answer 7

It's because it is in the Oort cloud .
They think it should just be in inner space to be a planet .

inner space means in the solar system ,
outer space means beyond the Oort cloud.