Pluto's fifth moon discovered

[supernova1965]

http://www.facebook.com/l.php?u=http%3A%2F%2Fwww.learnastro nomyhq.com%2Farticles%2Fplutos-fifth-moon-discovere.html&h=dAQFToTDV&s=1

At some point you have to question Pluto's status when it has five moons in orbit don't you:question:

[Darth Wader]

This was actually discovered around July last year.

http://en.wikipedia.org/wiki/S/2012_(134340)_1

[supernova1965]

Oops my bad:lol:

[barx1963]

Not really, having moons is not one of the criteria for planet status which are
<LI sizcache0390170421181596="54 161 8" sizset="false">is in orbit (http://en.wikipedia.org/wiki/Orbit) around the Sun (http://en.wikipedia.org/wiki/Sun), <LI sizcache0390170421181596="54 161 10" sizset="false">has sufficient mass to assume hydrostatic equilibrium (http://en.wikipedia.org/wiki/Hydrostatic_equilibrium) (a nearly round shape), and
has "cleared the neighbourhood (http://en.wikipedia.org/wiki/Clearing_the_neighbourhood)" around its orbit.
Given Haumea has satellites and there are maybe hundreds, thousands or millions of similar objects either with or without satellites, the status of Pluto as a minor planet makes perfect sense.

Malcolm

[astroron]

Cleared it's neighbourhood around its orbit ?????
I think the people of Russia may disagree with that.:rolleyes:
Or even maybe the Dinosaurs.:sadeyes:
Are you telling us that Pluto is not round :question:
Is Pluto not in orbit around the Sun:question:
The only thing going against Pluto is it's size as far as I can see.
Cheers:thumbsup:

[Astro_Bot]

... and it's eccentric orbit. ;)

Not that I profess to know what criteria the IAU applied when they demoted Pluto.

[astroron]

Eccentric or otherwise it is still in orbit around the Sun.
Cheers:thumbsup:

[Astro_Bot]

It's Monday morning, Ron. I don't think anyone was expecting this thread to be taken too seriously. :)



Malcolm already posted the IAU's new "planetary criteria", but this article (http://www.universetoday.com/13573/why-pluto-is-no-longer-a-planet/) explains Pluto's demotion in straightforward terms. Size didn't count against Pluto in the final analysis (it has enough mass to achieve hydrostatic equilibrium), but rather the third planetary criteria of "cleared the neighbourhood" around its orbit was the sticking point.

An object meeting the first two criteria but not the third is a "dwarf planet".

[astroron]

I was just reading the defination of a planet. here (http:/http://en.wikipedia.org/wiki/IAU_definition_of_planet)
I think they should not have included the third one,as there is no no planet that has done that,even Jupiter is not exempt.
I think Size did count, as that is one of the reasons Mike Brown even says so.
There is so much more as well.
Cheers:thumbsup:

[rcheshire]

Ron. Your link didn't work for me. Here (http://en.m.wikipedia.org/wiki/IAU_definition_of_planet) it is again - maybe?

[barx1963]

Ron. The definition of "cleared it's orbit" is "a planet (http://en.wikipedia.org/wiki/Planet) will have "cleared the neighbourhood" of its own orbital zone (http://en.wikipedia.org/wiki/Planet#Orbit), meaning it has become gravitationally dominant, and there are no other bodies of comparable size other than its own satellites (http://en.wikipedia.org/wiki/Natural_satellite) or those otherwise under its gravitational influence."

Obviously there will be asteriods meteorites etc crossing or sharing a planet orbits, but they are not of comparable size. As far as I am aware there are no objects of comparable size to Jupiter in it's zone. Pluto shares its orbital zone with Neptune and a host of Kuiper belt objects opf which it is not even the largest. Clearly it does not meet the definition.

The whole Pluto is a planet "debate" is IMHO rather silly, the IAU voted so as far as the IAU is concerned it ain't a planet. Of course, if you are not a member of the IAU one is perfectly at liberty to keep calling it a planet if one so desires!!

Malcolm

[astroron]

Rowland Try again here (http://en.wikipedia.org/wiki/IAU_definition_of_planet)
Cheers:thumbsup:

[astroron]

Malcolm, That the Resolution was approved by a vote of 237–157, with 30 people indicating their abstention shows that a great deal of scientist disagreed and shows there is still a lot of disagreement on this subject including the head of the "New Horizons" space craft probe to Pluto.
What I did find interesting in my wiki article was the statement that only planetary scientist needed to vote.
Astronomer Marla Geha has clarified that not all members of the Union were needed to vote on the classification issue: only those whose work is directly related to planetary studies.[44] (http://en.wikipedia.org/wiki/IAU_definition_of_planet#cite_note-marlageha-45)
If this discussion has done anything, is has provided information for people to make up their own mind.
your "Honest Opinion" is duly noted;)
Cheers:thumbsup:

[OICURMT]

I wonder if E.T. is thinking...

" Why are these humans getting caught up in the definition of a PLANET.... they are obviously 'Thinga Ma Bobs...' "... :)

[ving]

yup you have to wonder about that.... except i doubt those aliens know or even care if we exist :p
quite beside the point.

so to that 3rd point. I am sure it would be referring to items that would permanently reside in the orbit of the planet and not those that just cross its path? otherwise there are no planets by their description, yes?

[TrevorW]

It would have been far simpler and less controversial to leave it as it was, why vote on something that made no fundamental difference to science or affect the bulk of mankind just doesn't make sense to me but nor does the maths of quantum physics for that matter.

[barx1963]

Part of the IAUs function is to allocate names and define classes of astronomical objects. Nomenclature may sound like nitpicking unnecessary stuff, but being able to precisely define the things you are talking about is fundamental to good science. Given that if Pluto is accepted as a planet we would also have to accept Eris, Sedna, Quaoar and several other bodies along with potentially hundreds or thousands of others, a decision had to be made. Also, the definition of planets has changed before, back in the early 1800s the first asteroids (Ceres, Vesta, Pallas and Juno) were initially regarded as planets but as more and more similar objects were found the consensus emerged to define them as asteroids. This decision is simply continuing that tradition.

Malcolm

[TrevorW]

It's still is a planet in my eyes and will be until the day I die because that is what I grew up with and that is what I accept and a lot of other people would probably think the same.

[Blue Skies]

I would like to recommend Mike Brown's book "How I killed Pluto and Why it Had it Coming" as an excellent summary of history of solar system bodies discovery as well as his personal involvement in it. I have been much more accepting of the changes since reading that, and I would actually like to see more changes made in the way we classify planets as a result, as the current descriptions still don't fit all that well in my opinion.

As for the discovery of the 4th and 5th moons of Pluto, there's an interesting story behind that I'd love to be the one to tell one day soon (2nd hand, but still close to the source!)...I've just got a couple of other things to do first...

[supernova1965]

This is my point Pluto is no asteroid it has 5 moons it has gravitational control in its region it is spherical no planet has completely cleared its orbit so lets just say there are no planets because strict application of the new rule does just this to me this is just as silly as saying that Pluto isn't a planet. How many objects truly similar to Pluto are there I haven't heard of any objects out there with moons like Pluto?

[barx1963]

Once again Warren, as per my previous posts, the definition does not require "complete" clearing of the orbital zone, only clearing of objects of comparable size. Unless I am mistaken there are no objects comparable to Earths size in our zone (for example!).;)
Several minor bodies have satellites, the asteroid Ida has a moon named Dactyl, the dwarf planet Haumea has 2 moons and the dwarf planet Eris has 1 called Dysnomia. In any case, presence of satellites is not relevant as Mercury and Venus have no natural satellites.
Further on a historical note, in ancient Greece the planets included the Sun and Moon as all bodies than moved in the heavens were called planets. So we should not feel squeamish about updating our definitions.

Cheers

Malcolm

[supernova1965]

A planet is a celestial body that

(a) is in orbit around the Sun,
(b) has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape, and
(c) has cleared the neighbourhood around its orbit.


I understand your point but the defination as posted above taken from the IAU site doesn't state has cleared most of the objects in its orbit it says simply has cleared the neighbourhood around its orbit. They should change it to say cleared the orbit of significant objects this the only point that disqualifies Pluto as a planet so to disqualify Pluto this needs to be amended. Going by this one point as written there would be a lot less planets in our solar system.

[TrevorW]

Warren this is worth a look

http://www.universetoday.com/13573/why-pluto-is-no-longer-a-planet/