Why Pluto is not a planet?

Answer 1

According to the new definition, a full-fledged planet is an object that orbits the sun and is large enough to have become round due to the force of its own gravity. In addition, a planet has to dominate the neighborhood around its orbit.

Pluto has been demoted because it does not dominate its neighborhood. Charon, its large "moon," is only about half the size of Pluto, while all the true planets are far larger than their moons.

In addition, bodies that dominate their neighborhoods, "sweep up" asteroids, comets, and other debris, clearing a path along their orbits. By contrast, Pluto's orbit is somewhat untidy.

This is already generating controversy all over world and will force textbooks to be rewritten, Pluto will now be dubbed a dwarf planet.

Answer 2

The object Pluto is been reclassified by the International Astronomic Union (IAU) as a dwarf planet for a number of reasons. Firstly it's orbit crosses that of a very large object - Neptune - which is undoubtedly a planet. No other "real" planet has such an orbit. Secondly it's orbit is inclined to the ecliptic by quite a bit. Thirdly it is quite small, much smaller than the Earth's Moon.

Until the 1950s it was thought to be larger and heavier than the Earth and was therefore classified as a planet. Over the past 50 some years though, successively better measurements have shown that it is quite small.

A few years ago it was found to have a large satellite now called Charon and two smaller ones. Around the same time it became obvious that there were other objects in the outer solar system which were as about as big as Pluto. To save the list of planets getting cluttered up by multiple objects of smallish size the IAU classified Pluto along with the rest of them as dwarf planets.

Scientists re-classify thing all the time as better information comes to hand. It is frequently things like bacteria and plants but sometime animals. These are far more likely to affect us as they are right here on Earth but the story never gets in the news and few people get their knickers in a knot about it.

Look at the Wikipedia article for facts on Pluto.

http://en.wikipedia.org/wiki/pluto...

This question has been answered dozens of times under this heading. Edit - VIPUL is flat wrong.

Answer 3

Pluto was considered the Solar System's ninth planet. In the late 20th and early 21st centuries, however, many objects similar to Pluto were discovered in the outer solar system, most notably the scattered disc object Eris, which is 27% more massive than Pluto.On August 24, 2006 the IAU defined the term "planet" for the first time. This definition excluded Pluto from planethood, and reclassified it under the new category of dwarf planet along with Eris and Ceres.After the reclassification Pluto was added to the dwarf planet list

Answer 4

Secretly to me, Pluto will always be a planet. I am sick and tired of having things taken away from me as I go through life. I remember learning about out 9th planet when I was just a lad and by gosh, Pluto will be a planet to me when I am an old geezer.

But for the scientific community, if they want Pluto as a dwarf planet, then so be it. They could allow this and the justification could be that if the orbit of Pluto was not tilted with respect to the orbit of Neptune, these two heavenly bodies may have collided some distant time in the past. A second possibility is that Pluto could have been captured by Neptune and would then look like a moon of Neptune in every sense of the definition of a moon.

If either of these had occurred we would not be having any Pluto/planet debate. I like best that Pluto would be a moon of Neptune. It almost could be considered that now. It is at some times outside the orbit of Neptune and at other times inside the orbit of Neptune. Can we not make a similar statement about the earth and earth's moon. Sure, sometimes the moon is outside the earth's orbit and at other times inside the earth's orbit.

So in summary:

4 the scientists: My very educated mother just served us Nine.
4 Me, well I am still eating pizza......lol


I came across this interesting website about Pluto

http://www.abc.net.au/science/space/planets/pluto.htm

just wanted to share

PS: If the scientists need something to do, why don't they come up with a catchy name for earth's moon and get everybody to use it. We know it's a moon, that's what it is. Isn't that kinda like taking Earth and changing its name to Planet? Just kidding.

Answer 5

Short answer: it does not fit the latest definition of a planet, as determined by the International Astronomical Union (IAU).

Long and boring answer:
The word planet comes from the Greek aster planetes (wandering stars) and was given to light sources that moved amond the fixed stars. There were 7: Sun, Moon, Mercury, Venus, Mars, Jupiter, Saturn (Greeks used their Greek names, of course).

The first change came after Copernicus and Kepler proposed the sun-centred system. By the time the new system was accepted, Galileo had discovered 4 tiny stars that "wandered" around Jupiter, and these were called planets in his original writings. The Sun and the Moon lost their planet status. We had things called satellites: our Moon, Jupiter's moons and a few around Saturn (depending when your country accepted the new system).

In the late 18th century (1700s), it was thought that the position of planets was set by a simple mathematical rule called Titius-Bode's law. According to it, a planet was missing between Mars and Jupiter. In 1801, Ceres was discovered. It was the missing planet. Then (as people kept looking), they found Pallas, Juno and Vesta. Four planets in orbits between Mars and Jupiter.

Things stayed quiet for a while, until the middle of that century when a whole bunch more were found (Astraea, Hebe, Iris, Flora...). Astronomers realised that there were a lot of small objects all sharing the same family of orbits. They concluded that these objects were not really planets, they were much too small. They were asteroids (because they still looked like points of light through telescopes, not like planets that show a disk).

So, Ceres, Pallas Juno and Vesta lost their planet status and became "minor planets".

Meanwhile, after Uranus was found, astronomers noted that its orbit was perturbed. Mathematical calculations led to the conclusion that there was another planet out there: they looked for it and found Neptune. The planet predicted by math.

Analysing Neptune's orbit, astronomers predicted yet another planet beyond it. When Pluto was found, it was at first thought that it was the new planet responsible for perturbations in Neptune's orbit.

It took a long time to get accurate info on Pluto. Now we realise that it is much too small to have been the predicted planet (and it was not in the right place when it was found) and there are more similar objects sharing the same family of orbits. Wanting to avoid a repeat of 1801-1855, the IAU decided to refine, once again, the definition of the word planet.

Pluto (and other similar objects already found) are dwarf planets.

We now have:
planets
dwarf planets
minor planets
planetoids
(along with satellites, comets, meteoroids...)

Answer 6

Pluto is not a planet because its orbit of revolving is cut from the orbit of revolution so it is said that the Pluto is not a planet it is a moon of our eighth planet Neptune.

Answer 7

Because Science decided to pattern itself after the US Congress and pass silly compromized legislation that does nothing for no one.

A lot of scientsts are up in arms over this.

It has to do with size and the fact it's orbit takes it inside Neptune.

It had long been though that Pluto might be an escaped moon of Neptune.

Answer 8

Until Pluto cleans up its orbit, it will not be a grown up planet.

Answer 9

Pluto is not a planet because of its size... Pluto and its satellite Charon has almost the same size...

Answer 10

i can't beleive how many people have their info messed up. pluto doesn't orbit neptune. it's not a planet because it hasn't cleared it's neighborhood of other objects. ie, it's moon charon is too close to it and affects it's orbit