Regarding Pluto

Soldato
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Hi folks, long time no see.

I know that Seti and space sciences are no longer the main topics of interest in this forum now, but I'm hoping that there are enough of the original Seti folks, and those interested in space sciences in general that this post won't be out of place.

I'm sure you've all heard the news about Pluto losing it's status as a planet, and are aware that more than a few interested parties do not agree with the decision for various reasons.

When the announcement was originally made, I read about it on http://spaceweather.com, after reading the article that was posted at the time, and the rules as laid forth by the IAU as to what would define a planet from now on, I sent an email to the webmaster of the site, asking him if he had any thought as to the status, specifically the fact that one of the supposed new guidelines required:

It must reign supreme in its own orbit, having "cleared the neighborhood" of other competing bodies.

Yet Neptune had kept it's status as a planet, even though the orbit of Pluto intersected with the orbit of Neptune.

Today I received a response from him:

Dr. Tony Phillips
<[email protected]>

Dear Mark,

Your point about Neptune is well taken. That does seem to be a flaw in the current IAU definition of planet.

I've just completed work on a "Pluto Petition" web page where anyone can make their feelings known about the status of Pluto:

http://plutopetition.com

with a companion essay here:

http://plutopetition.com/unplanet.php

Any comments you have would be welcomed. --Tony

I personally think that it is incorrect that only 5% of the worlds astronomers should be able to make a change of this magnitude, and that the situation has not been considered fully, when you take into account that Neptune is considered to be a planet, yet does not meet all of their guidelines.

I personally think that the whole situation needs to be looked at in much more detail before making such a sweeping change.

Yes, I admit that Pluto is very small in size, and it would open the door for other bodies to be recognised as planets if Pluto is reinstated, however, I think that the decision was made by too few people with too little consideration.

If any of you are interested enough, perhaps you could take a couple of minutes to have a look at the site that Dr Phillips has put up, and maybe sign the petition, either for or against the current situation.

Regards to you all,

Mark.
 
Soldato
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some of us old seti guys are still here!

it feels kinda odd realy, I think pluto should be given dispensation and just left as a planet, it just feels right!
 
Associate
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hmmm I dunno, I see all the points, but aren't there several more pluto sized planets beyond pluto? Surely if Pluto is to remain a planet then they should all also be made official planets. It is a tricky one indeed. Every solution except 'leave it as it is for legacy reasons' has its flaws.
 
Soldato
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It must reign supreme in its own orbit, having "cleared the neighborhood" of other competing bodies.

If this is taken literally then no planets would be able to remain, because the orbit of every one of them is bound to be intersected at some point, such are the numbers of asteroids/meteoroids/comets that populate the Solar System. Earth would certainly be demoted as a result of the so-called Near Earth Objects (NEOs), as would the other terrestrial planets, sometimes with the one asteroid crossing two or more of their paths (example). The Pluto-Neptune situation is the most well-known one, where Pluto is closer to the Sun for about twenty years of its 248 year orbit. Three planets - Mars, Jupiter and Neptune - are known to have associated Trojans, which are essentially clusters of asteroids that have been captured by the planet's gravity and share its orbital path at one or more Lagrange points. In these cases, the neighbourhood has hardly been cleared.

I think the above statement is meant to be taken with a slight pinch of salt and a good dose of common sense. An object in the Asteroid Belt, for example, is just one of probably hundreds of thousands that occupy a similar region and is therefore in a relatively dense 'neighbourhood' when compared to an object (planets) that has only a few hundred bodies that cross its orbit regularly.

As a result, I think it's right that Pluto has been demoted; although it's spherical and orbits a star, it resides within the Kuiper Belt (akin to the Asteroid Belt), which is relatively dense compared to all other planets' orbits and is therefore in an 'uncleared' region. The Kuiper Belt is in an area outside of Neptune's orbit, which would provide a good reason for Neptune remaining as a planet - it has cleared its 'neighbourhood' enough to qualify for planetary status under the IAU rules, with just a relative handful of objects - Pluto included - crossing its path.
 
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Associate
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Yet Neptune had kept it's status as a planet, even though the orbit of Pluto intersected with the orbit of Neptune.

Thats excactly why Neptune has kept its status. Its Pluto's orbit that intersects with Neptunes.

TBH I don't think Pluto was ever a planet anyway. I think it was just a large asteroid that got caught in the suns gravity well and wound up with a relativly tight orbit compared to other asteroids or meteorites.
 
Soldato
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VeNT said:
I was just wondering about that, will neptune and pluto ever collide?

No. Pluto and Neptune are in a 3:2 resonant orbit (for every three complete orbits that Neptune does, Pluto does two), making it impossible for a collision to happen. As it happens, the two aren't even remotely close to colliding. Link
 
Man of Honour
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There is some technical reason that I can't remember right now that apparently causes most/all asteroids not to count towards having 'cleared the neighbourhood'. Unfortunately, in the case of Pluto, Charon is very similarly sized and hence the IAU ruling.

I still think the IAU ruling is ill-thought-out factionally-motivated stupid turd. It was sprung on the IAU conference on the last day, when most astronomers had already left for home, and thus got railroaded through. The sooner it's taken outside and exterminated, the better. Yesterday would be ideal.
 
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