What are some of the reason scientists are using to re-classfiy Pluto from its status as a planet?

Question

Is there a new sort of definition of a planet that could be used to possibly include it as a planet? (without using obvious charaterisitcs like mass etc..)

AND- If we could find a definition to include Pluto would that mean there are some asteroids and comets that we would have to say are planets too??

**Sorry i have such a long question

Answer 1

"If we could find a definition to include

Pluto would that mean there are some

asteroids and comets that we would

have to say are planets too??

"

That is the problem.  There are several objects we know of that would fit a planet definition if Pluto fit the definition.  There are four known dwarf planets- Ceres, Pluto, Makemake and Eris.  Eris is more massive than Pluto.  Many more “dwarf planets” are likely to be discovered soon.  It is suspected that at least another 41 discovered objects in the Solar System might belong in this category.

Answer 2

because scientists believe pluto is a comet that drifted into our solar system orbit , because it is a giant ball of ice. Other asteroid and comets are not confused as planets because theyre smaller (asteroids) and comets are classified as a body of rock, ice, and dust. So we dont call asteriods planets because they are just debris left from the forming of other massive bodies like stars, planets, and sattlites (moons).

    Best Regards,

Answer 3

Well, really, if Pluto's considered a planet, there may be as many as 50 other Pluto-sized objects and larger beyond Pluto's orbit, which means we'd have to learn up to 60 or 65 names of planets.  

Better to reclassify Pluto, and keep the number of true planets at 8, and just add to the "Kuiper Belt Object" list (Or a new term - "Plutoids.")  

Answer 4

Published: August 24, 2006

Pluto Is Demoted to ‘Dwarf Planet’

It has long been clear that Pluto stood apart from the previously discovered planets. Not only was it much smaller than them, only about 1,600 miles in diameter, smaller than the Moon, but its elongated orbit is tilted with respect to the other planets and it goes inside the orbit of Neptune part of its 248-year journey around the Sun.

Pluto makes a better match with the other ice balls that have since been discovered in the dark realms beyond Neptune, they have argued. In 2000, when the new Rose Center for Earth and Space opened at the American Museum of Natural History, Pluto was denoted in a display as a Kuiper Belt Object and not a planet.

Two years ago, the International Astronomical Union appointed a working group of astronomers to come up with a definition that would resolve this tension. The group, led by Iwan Williams of Queen Mary University in London, deadlocked. This year a new group with broader roots, led by Owen Gingerich of Harvard, took up the problem.

According to the new rules a planet meet three criteria: it must orbit the Sun, it must be big enough for gravity to squash it into a round ball, and it must have cleared other things out of the way in its orbital neighborhood. The latter measure knocks out Pluto and Xena, which orbit among the icy wrecks of the Kuiper Belt, and Ceres, which is in the asteroid belt.

Dwarf planets only have to be round.

“I think this is something we can all get used to as we find more Pluto-like objects in outer solar system,” Dr. Pasachoff said.

The final voting came from about 400 to 500 of the 2,400 astronomers who were registered at the meeting of the International Astronomical in Prague. Many of the astronomers, Dr. Pasachoff explained, had already left, thinking there would be nothing but dry resolutions to decide in the union’s final assembly.

In the new solar system, there are eight planets, at least three dwarf planets and tens of thousands of so-called “smaller solar system bodies,” like comets and asteroids.

For now, the dwarf planets include, besides Pluto, Ceres, the largest asteroid, and an object known as UB 313, nicknamed Xena, that is larger than Pluto and, like it, orbits out beyond Neptune in a zone of icy debris known as the Kuiper Belt. But there are dozens more potential dwarf-planets known in that zone, planetary scientists say, and the number in that category could quickly swell.

Jun 11, 2008

Plutoid chosen as name for Solar System objects like Pluto

Plutoids are celestial bodies in orbit around the Sun at a semimajor axis greater than that of Neptune that have sufficient mass for their self-gravity to overcome rigid body forces so that they assume a hydrostatic equilibrium (near-spherical) shape, and that have not cleared the neighbourhood around their orbit. Satellites of plutoids are not plutoids themselves, even if they are massive enough that their shape is dictated by self-gravity. The two known and named plutoids are Pluto and Eris. It is expected that more plutoids will be named as science progresses and new discoveries are made.

The dwarf planet Ceres is not a plutoid as it is located in the asteroid belt between Mars and Jupiter. Current scientific knowledge lends credence to the belief that Ceres is the only object of its kind. Therefore, a separate category of Ceres-like dwarf planets will not be proposed at this time.

Answer 5

The new definition of a planet excludes Pluto.

In order to be a planet, it has to do all these four things.

1) Orbits a star (Pass)

2) Have enough mass for its gravity to make it round (Pass)

3) Not massive enough to cause thermonuclear fusion (Pass)

4) Has cleared the neighborhood (FAILED.)

Clearing the neighborhood means that its gravity is strong enough for it to clear the debris out of its orbit.  



And yeah, if Pluto was a planet, then you could classify a million other things in our solar system as a planet.  It's easier for everyone to keep it as a dwarf planet.

Answer 6

Because Neil deGrasse Tyson wanted to be noticed in a business where it is publish or perish... When he got control of the Hayden Planetarium he removed Pluto to be noticed by the scientific community and started a big stink that ended with him being up one science wise and we are down one planet wise.

It's also why we can't let scientists run anything even with their huge brains... Because they all have much, much larger egos…

Answer 7

you need to look at the mass ,size, orbital trajection , if it has any moons . pluto doesn't meet all of the standards to be considered a planet . So they label it a dwarf planet . so asteroids and comets cant have a sustainable orbit and moons .  

Answer 8

There will likely never be a solution accepted which restores Plutos status out of plain romantic feelings towards it.

Remember the facts: It is in a very unusual orbit compared to the 8 remaining planets. It is smaller as many other small objects in the solar system. It is not even dominating it's orbital neighborhood - it is just one object among many in the region.

That it got rated as Dwarf planet is already a pretty sentimental solution - without this new category, it would have been just another small object in the solar system.

Answer 9

The International Astronomical Union defined a planet in 2006. Prior to then, we did not have a definition for planets. The planets out to Saturn are visible without a telescope, so have always been known. Consequently we didn’t have a definition for a planet before!

Ceres, the largest asteroid and the first to be discovered was originally classified as a planet, and kept this status until we discovered that it was just the largest of a class of objects we now call asteroids.

Pluto was only discovered in 1930 and it is now clear that it is actually the largest of a class of objects we now call Kuiper Belt Objects.

Consequently we now have a new class of objects called Dwarf Planets, which included Pluto and Ceres, but should also include Eris, Quaoar, and Sedna as well as several objects that are currently unnamed (they have numbers) and maybe a couple of other asteroids.

If you want to keep Pluto as a planet, you need to promote Ceres back to planet status, and you need to promote the other Dwarf Planets - necessitating textbook re-writes anyway.

In fact there are other properties of Pluto, beyond the IAU definition issues, that distinguish it from the planets:

1) Its orbit is not in the same plane as the planets

2) Its orbit is much more elongated (eccentric) than the planets - which is more like comet-behavior)

3) It only develops an atmosphere close to perihelion (when it is closest to the sun (which again is comet-lke behavior)

Since the Kuiper belt is where many comets from, we might class Pluto as a proto-comet.

You can download my powerpoint presentation from: http://stardust.astro.missouri.edu/FTP/

the file is called: Pluto_talk.ppt

(original – huh?)