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Mass of Dwarf Planet Eris 27% Greater than Pluto

Zonk posted more than 7 years ago | from the she-wants-a-bite-of-the-apple dept.

Space 220

jcgam69 writes "When it was discovered in 2005, some thought Eris should be considered the 10th planet of our solar system. Everyone still considered Pluto a planet then. At first, Eris was thought to be slightly larger. Now — with the help of Eris' moon — Eris is known to be 27% more massive than Pluto. If Pluto had remained a planet to the entire community of astronomers, surely Eris would be considered the 10th planet."

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Haiku on a Distant Rock (4, Funny)

Anonymous Coward | more than 7 years ago | (#19512557)

Poor lonely Pluto;
No one loves you now but me.
And Clyde Tombaugh [wikipedia.org] 's urn.

Re:Haiku on a Distant Rock (4, Interesting)

Ucklak (755284) | more than 7 years ago | (#19512873)

Poor Pluto [mathiaspedersen.com]

music video (1)

the_mighty_$ (726261) | more than 7 years ago | (#19512937)

Poor lonely Pluto;
No one loves you now but me.

You actually aren't alone. These guys [youtube.com] were so moved with affection for Pluto that they created a music video. Rock on, Pluto!

Re:music video (1)

EvanED (569694) | more than 7 years ago | (#19513437)

There's also Jonathan Coulton's I'm Your Moon, a love song from Charon to Pluto.

Watch this video [youtube.com] for his introduction to the song, but you can download (for free -- CC license -- or buy) an MP3 here [jonathancoulton.com] , since the video cuts out briefly every couple minutes.

That planet is for gays. (-1, Flamebait)

Anonymous Coward | more than 7 years ago | (#19512571)

Everyone knows that Pluto is the San Francisco of the solar system.

Re:That planet is for gays. (1)

BakaHoushi (786009) | more than 7 years ago | (#19513939)

I find this to be highly illogical and foolish. How can you say that with a planet nearby called URANUS? The joke is as old as the name. Clearly, you are either clueless to astronomy, or a troll.

Personally, Pluto shouldn't be so down. It has confirmed land. Jupiter, Saturn, Uranus (or as it will later be known, Urectum), (and possibly Neptune) do not. "Hey Jupiter, I bet you can't wait to have someone land on you and plant a flag... oh, wait, that's right. YOU CAN'T!" "Hey, Saturn, look what I can do. Notice all this SOLID I can do, hmm? Why don't you give it a try sometime!"

New Nmemonic (5, Funny)

DTC (450482) | more than 7 years ago | (#19512589)

My Very Excellent Mother Just Serverd Us Nine Pizzas- Excelsior!

Re:New Nmemonic (2, Funny)

Wah (30840) | more than 7 years ago | (#19512843)

and post-plutpwnage it becomes...

My Very Excellent Mother Just Serverd Us Ninja Excrement.

Re:New Nmemonic (0)

Anonymous Coward | more than 7 years ago | (#19513125)

Shouldn't that be "Mnew Mnemonic?"

My Very Excellent Mother Just Served Us NOTHING! (1)

Tatarize (682683) | more than 7 years ago | (#19513369)

Yeah, but Pluto got voted out... so now.

My Very Excellent Mother Just Served Us NOTHING!

You know, Pluto had a good thing going until these stupid other transneptunian objects started to to clutter sky and make people turn on poor little Pluto. It's like being able exploit a flaw in a game. It works great for a while, but then a bunch of people do it and you're screwed.

Hail Eris! (5, Funny)

subl33t (739983) | more than 7 years ago | (#19512597)

All Hail Discordia!

Hail yes!

fnord.

Re:Hail Eris! (1)

prat393 (757559) | more than 7 years ago | (#19513141)

I dedicate the flying rock in space named Eris to the prettiest one.

Re:Hail Eris! (1)

h4rm0ny (722443) | more than 7 years ago | (#19513185)


In classical fashion, Eris has upset the applecart by triggering an argument over whether calling Pluto a planet or not is the fairest decision. What is the gold standard?

The not-so-littlest dwarf planet (1)

ackthpt (218170) | more than 7 years ago | (#19513511)

"It's barely enormous!"
"It's merely huge!"

What can I say... (3, Funny)

setirw (854029) | more than 7 years ago | (#19512629)

...our beloved ninth planet just got plutowned!

Re:What can I say... (1, Interesting)

stefanlasiewski (63134) | more than 7 years ago | (#19512875)

I thought Pluto got Erised from history.

Re:What can I say... (1)

h2g2bob (948006) | more than 7 years ago | (#19513005)

our beloved ninth planet just got plutowned
Not really. Pluto and Charon form a binary system. Together they outmass this upstart.

If it's round (2, Insightful)

Profane MuthaFucka (574406) | more than 7 years ago | (#19512641)

it's a planet. If it's orbiting a larger planet, then it's a moon.

This is just a classification problem. In my company, the secretary takes care of that shit. WHY ARE WE wasting our time with this crap? I don't give a shit if some schoolkid has to memorize dozens of planets. That's between him and his teacher.

Re:If it's round (0)

Anonymous Coward | more than 7 years ago | (#19512945)

Think about the asteroid belt, man! There's a plethora of round objects to be found just beyond Mars! Planets galore!

Re:If it's round (1)

N3WBI3 (595976) | more than 7 years ago | (#19513119)

Most of those are not round as in spherical. Pluto and Eirs have enough mass to collapse into spheres despite the rigidity of the components that collided to form them. Where they fail the new planet test is by not having enough mass to clear their orbits..

Re:If it's round (1)

mdwh2 (535323) | more than 7 years ago | (#19513225)

Quite a few of them are round I believe, we'd certainly have quite a few extra.

Though that wasn't the OP's definition anyway, he was saying that anything orbiting the sun should be a planet. Not that I think there's a problem with that - we use his definition for moon, after all, there's no awkward requirements for "must be round" or "must be minimum mass" or "must clear its orbit". As long as we can identify a particular piece of rock, it gets labelled a moon.

Re:If it's round (1)

mdwh2 (535323) | more than 7 years ago | (#19513251)

Oops, didn't see the subject line - I see he did specify a planet should be round. But as I say, quite a few of the asteroids are.

Re:If it's round (1)

N3WBI3 (595976) | more than 7 years ago | (#19513285)

Can you point me at a round asteroid in the belt?

Re:If it's round (5, Funny)

Paradise Pete (33184) | more than 7 years ago | (#19513393)

Can you point me at a round asteroid in the belt?

OK, look up. A little more to your left. A bit more. OK, just a little bit more. Nope, that's too far. Just a hair back to your right. There! See it?

Re:If it's round (0)

Anonymous Coward | more than 7 years ago | (#19513463)

Ceres comes to mind.

Re:If it's round (2, Informative)

jonatha (204526) | more than 7 years ago | (#19513687)

Ceres and Vesta

Re:If it's round (2, Informative)

poopdeville (841677) | more than 7 years ago | (#19512955)

You're a member of the IAU? Otherwise, you must be using the Royal we.

In any event, the "dwarf planet" classification is informative. Dwarf planets have sufficiently low mass that they have no managed to clear their orbital path from other massive objects. Their properties are very different, despite orbiting the sun and being round.

Why use a cluttered ontology when a clean one can be designed?

Where is this "clean" ontology you speak of? (0)

Anonymous Coward | more than 7 years ago | (#19513619)

So are you saying that Pluto will never clear it's orbit path? Do we know that, or do we change Pluto's designation when it does (in the distant future). And what if we find a planetary system that has two massive planets on the same or near orbit path but on opposite sides of their star. Are they not planets because they havn't cleared their orbit path? And of what significance is this definition of "cleared" aside from it's unnerving likeness to the sphincter it was pulled from?

I'd also love to hear you try to articulate how these very different properties you speak of actually mark some significant change in characteristics greater than that of any other two objects you would call planets.

Why use a convoluted ontology when a simple one would suffice?

Re:Where is this "clean" ontology you speak of? (4, Informative)

CorSci81 (1007499) | more than 7 years ago | (#19513801)

Pluto won't clear its orbital path in the lifetime of the sun for a few reasons. The Kuiper Belt (where Pluto resides) is a very excited region of the solar system in terms of orbital eccentricities and inclications, which results in a very high mean impact velocity between objects out there. This means impacts tend to be destructive rather than letting anything grow larger. Additionally the number of particles in the Kuiper belt is sufficiently small impacts are fairly rare. Basically, the Kuiper Belt never became a planet for much the same reason the asteroid belt hasn't.

Regarding the two planets bit, that's a highly unstable orbital configuration. If they orbited a common center of mass (like the Earth and moon) it would be feasible, but then we'd just call them a twin planetary system, or the smaller of the two would be considered a moon.

Re:If it's round (4, Interesting)

Pfhorrest (545131) | more than 7 years ago | (#19513169)

it's a planet. If it's orbiting a larger planet, then it's a moon.

What, no distinction between round moons and non-round moons?

I think we need to have our system of classifications able to accurately distinguish between:

- Bodies of sufficient mass that they would undergo fusion if of fusionable composition (stars).
- Amongst those, ones which are of fusionable composition (active stars) versus those which no longer are (inactive stars).
- Amongst non-stars, bodies which are of sufficient mass to be approximately round (major planets) versus those which are not (minor planets or asteroids)
- Amongst planets, those which have an orbit centered on a star (regular planets) versus those which do not (irregular planets).
- Amongst irregular planets, those which have an orbit centered on another planet (moons) versus those which do not (asteroids).

Thus, Phobos and Deimos are minor irregular planets, and also moons (call them just "minor moons" since all moons are irregular planets); while similar bodies in the asteroid belt are also minor irregular planets, but are not moons but rather asteroids. Europa and Ganymede are a major irregular planets and also moons ("major moons"). Luna is a major moon. Eris and Pluto (if I understand the irregularity of their orbits correctly) are major irregular planets and also asteroids (or just "major asteroids", for all asteroids are irregular planets). Earth, Mars, etc are major regular planets, and schoolkids can memorize those and ignore the rest; for simplicity of terminology we can always assume "major" and "regular" unless specified otherwise, so "planet" alone refers just to bodies like those.

There now, everybody happy? Pluto is a planet; it's even a major planet; however, it's an irregular major planet and thus not a "planet" simpliciter.

Correction & Addendum (1)

Pfhorrest (545131) | more than 7 years ago | (#19513347)

- Amongst non-stars, bodies which are of sufficient mass to be approximately round (major planets) versus those which are not (minor planets or asteroids)
Er, scratch that "asteroids" bit, that was written in error.

Also, it dawns on me that all non-stars are planets (though not planets simpliciter) by this system of classification, so, this line merely distinguishes between major and minor planets.

On that note, it would probably also be useful to distinguish first between bodies at rest upon other bodies (like me and this computer) versus bodies in freefall (like all the forgoing bodies), for I'm uncomfortable with myself being classified as either a star or a planet. We could call the latter "celestial" bodies and the former, say, "terrestrial".

sell outs (0)

Anonymous Coward | more than 7 years ago | (#19512661)

if you call it a dwarf planet it only means that you're a sell out poseur. you can't take my planets from me!

Huge purple penis (-1, Troll)

Anonymous Coward | more than 7 years ago | (#19512665)

In your butt. [goatse.cz]

Re:Huge purple penis (2, Funny)

Poromenos1 (830658) | more than 7 years ago | (#19512735)

You got it wrong, that's Uranus.

So let 'em both in (2, Insightful)

FlyByPC (841016) | more than 7 years ago | (#19512691)

Pluto is big enough to have a moon (okay, so Pluto/Charon is really a double planet). Eris is more massive than Pluto. Sounds like they should both get to (re)join the club. Why not?

Re:So let 'em both in (5, Interesting)

ushering05401 (1086795) | more than 7 years ago | (#19512827)

The funniest thing to me is that we are so fixated on the planet/not-a-planet debate. Let em both in, don't let either in...

Both bodies will continue to be studied, and when the time comes, they will be exploited for their natural resources.

This debate will only matter fifty years from now when we actually begin mining other planets and mining related laws discriminate between bodies with different scientific designations.

Regards.

Re:So let 'em both in (1)

Kelson (129150) | more than 7 years ago | (#19512919)

Pluto is big enough to have a moon (okay, so Pluto/Charon is really a double planet).

Sure, but the asteroid Ida has a moon, Dactyl [nasa.gov] , as well, so I'm not sure that's useful criteria for planethood.

Re:So let 'em both in (1)

KC1P (907742) | more than 7 years ago | (#19513773)

>Eris is more massive than Pluto. Sounds like they should both get to (re)join the club. Why not?

Because they were both discovered by Americans. Don't be naive!

Pluto is still a planet (1)

Ryunosuke (576755) | more than 7 years ago | (#19512697)

Some of us still consider Pluto a planet.

Re:Pluto is still a planet (0)

Anonymous Coward | more than 7 years ago | (#19512761)

Some of us still consider Pluto a cartoon dog.

Re:Pluto is still a planet (1)

Anonymous Coward | more than 7 years ago | (#19513921)

Some of us still consider Pluto a cartoon dog.

You must be Goofy.

Re:Pluto is still a planet (0)

Anonymous Coward | more than 7 years ago | (#19512765)

Some of us consider Titan a planet too.

Of course those people are wrong, and so are you.

Re:Pluto is still a planet (0)

Anonymous Coward | more than 7 years ago | (#19512791)

...and the rest of us are qualified to have an opinion.

Re:Pluto is still a planet (3, Insightful)

geekoid (135745) | more than 7 years ago | (#19512797)

Some of us still consider that the world is flat.

Change can be hard.

Re:Pluto is still a planet (1)

nbert (785663) | more than 7 years ago | (#19513029)

you are trying to make fun of this, but It's easy to fool the untrained eye.

Re:Pluto is still a planet (1)

Jarjarthejedi (996957) | more than 7 years ago | (#19513931)

Well except for the fact that one is a completely arbitrary judgment which doesn't affect science at all and the other is something that has been proven wrong by evidence numerous times (sorry flat-earthers) you have it right.

Re:Pluto is still a planet (1)

phishen (1044934) | more than 7 years ago | (#19513361)

Pluto is only 73% the planet Eris is.

Silly question (0)

slickwillie (34689) | more than 7 years ago | (#19512699)

but wouldn't they have to know the mass of Eris's moon in order to make the calculations?

(BTW, what ever happened to naming it Xena?)

It was a nickname (3, Informative)

Kelson (129150) | more than 7 years ago | (#19512863)

(BTW, what ever happened to naming it Xena?)

Xena was never more than an unofficial nickname. No one, including the person who discovered it, ever intended for Xena and Gabrielle to be the official names for this pair of heavenly bodies.

Re:It was a nickname (1)

jollyreaper (513215) | more than 7 years ago | (#19513247)

Xena was never more than an unofficial nickname. No one, including the person who discovered it, ever intended for Xena and Gabrielle to be the official names for this pair of heavenly bodies.
Plus the Christians would go nuts, seeing it as a sign of further support for the homosexual agenda.

Re:It was a nickname (1)

tyrantking31 (1115607) | more than 7 years ago | (#19513885)

There already are two heavenly bodies named Xena and Gabrielle. If you know what I mean.

Re:It was a nickname (1)

Jarjarthejedi (996957) | more than 7 years ago | (#19513949)

Hehe, he said heavenly body and Xena...hehe

Re:Silly question (3, Informative)

Bramantip (1054582) | more than 7 years ago | (#19512991)

Gravity provides the centripetal force needed to keep satellites in orbit. If you focus on the simple case of circular orbits, you can use the centripetal force formula with the law of gravity to determine the mass of a planet. Simply set the force of gravity equal to the centripetal force and solve for the mass of the planet M.

M = r * v^2 / G

The period of Eris' moon provides another way to calculate its mass.

Period T = 2pi * sqrt(r^3 / G*M)

Thus I imagine the various images of the moon provided a way to calculate its period and indirectly determine the mass of the central body.

However the article doesn't give any specifics. It would be interesting to know what methods they used and the degree of accuracy of their measurements.

JJ +

Re:Silly question (0)

Anonymous Coward | more than 7 years ago | (#19513829)

If you have full text access to Science the relevant article is here:

http://www.sciencemag.org/cgi/content/full/316/583 1/1585 [sciencemag.org]

it matters? (1)

mastershake_phd (1050150) | more than 7 years ago | (#19512713)

What does it matter what its classified as? Its still a big frozen chunk of rock in the middle of nowhere. I guess the only difference is if it will be taught in school.

Re:it matters? (1)

mastershake_phd (1050150) | more than 7 years ago | (#19512979)

Has anyone come up with a new mnemonic device? My very eager mother just...

Re:it matters? (0)

Anonymous Coward | more than 7 years ago | (#19513007)

What does it matter what its classified as? Its still a big frozen chunk of rock in the middle of nowhere. I guess the only difference is if it will be taught in school.
Of course it will be taught in school. The only thing this affects is whether kids are told God made it before or after lunch on the first day.

Plan Nine (1)

Digital Vomit (891734) | more than 7 years ago | (#19512715)

You see? You see? Your stupid minds...stupid! Stupid!!

(Okay, so it's "Eris" and not "Eros". Sue me.)

Kuiper belt (2, Insightful)

blind biker (1066130) | more than 7 years ago | (#19512729)

The Kuiper belt, I am sure, contains still some surprises for us. Perhaps many surprises, and who knows, maybe some of them unpleasant. I wouldn't be surprised if Neptune one day grabs one of those rocks and launches it over here. That'll be lots of fun.

Kallisti (0)

Anonymous Coward | more than 7 years ago | (#19512743)

all hail, etc.

Good! Zonk! (-1, Offtopic)

Anonymous Coward | more than 7 years ago | (#19512751)

This is (unlike your other "stuff") news that is interesting, informative and relevant to the interests of nerds.

Let's hope your next article isn't about SCO or Jack Thompson.

every one knows . . . (2, Informative)

jd142 (129673) | more than 7 years ago | (#19512817)

That Mondas is the 10th planet. Duh.

grandfathered (0, Flamebait)

Secret Rabbit (914973) | more than 7 years ago | (#19512819)

I still don't understand why Pluto couldn't be 'grandfathered in' as a planet and still have the new definition. It's a way that everyone could have there way. This new guy would be a 'dwarf planet' (or whatever these politicians want to call it this week) and we'd still have Pluto if only for historical reasons.

Then again, there are those of us that have just ignored this ruling all together and still consider Pluto a planet.

Quite frankly, I'm really getting sick of the jackasses sitting around drinking whisky coming up with new names for things from time to time in an attempt to justify there existence. I really don't think that this one is going to be dropped for some time to come.

Re:grandfathered (2, Informative)

Metasquares (555685) | more than 7 years ago | (#19513001)

This is science we're talking about. 'Grandfathering' a planet would be like declaring 1 a prime because it was treated as one in the past. If we did this, we'd have to start explicitly making exclusions for the grandfathered planet/number ("all planets except Pluto are...").

Consistency is important in science.

Re:grandfathered (1)

Tumbleweed (3706) | more than 7 years ago | (#19513117)

Keep in mind, there are those of us who consider the definition of a planet as wrong, and the 'reclassification' as merely an attempt to exclude Pluto as a planet for the sake of scientific contrariness.

Re:grandfathered (2, Informative)

ZombieWomble (893157) | more than 7 years ago | (#19513157)

Except this isn't really science. This is a labeling problem. The only things this definition affects are other labeling issues, and occasional problems of ambiguity in certain forms of casual conversation. I can think of no real technical situation where this would cause an issue, and the whole fuss is rather silly and gives some people a fairly low opinion of science.

As an example I was watching some random evangelical show late one night (I had insomnia) while the main debate was going on. There was a whole segment dedicated to how scientists "didn't know" whether Pluto was a planet or not and how this clearly meant that they couldn't possibly make definitive statements on things like evolution and so forth. Of course to anyone involved in science the flaw in this argument is obvious - and neatly serves to indicate how the "planet" label isn't really that significant from any technical point of view.

Re:grandfathered (0)

Anonymous Coward | more than 7 years ago | (#19513289)

"Planet" is both a science term and a common trivia topic. Trivia tests if you know astronomy, not the other way around. Science decides, and trivia follows.

Re:grandfathered (1)

Secret Rabbit (914973) | more than 7 years ago | (#19513399)

You're example fails to prove your point as 1 IS considered prime by some.

But, even using your example, your example fails. If you knew anything about number theory you'd realize that 1 HAS to be treated as a special case in... many proofs.

Re:grandfathered (1)

Oktober Sunset (838224) | more than 7 years ago | (#19513721)

Hey, they still define current as flow of positive charge, when really it's the negative charge that flows, just because that's how it was defined in the past.

If they can be inconsistent for electrons, why can't they be for planets?

Re:grandfathered (1)

mdwh2 (535323) | more than 7 years ago | (#19513341)

I demand that we also "grandfather" in Ceres, Pallas, Juno, and Vesta, for historical reasons.

Some of us still consider them to be planets, and are really getting sick of the jackasses who keep changing their names (minor planets? asteroids? dwarf planet?)

It's not like we could go there anyway... (1)

MobileTatsu-NJG (946591) | more than 7 years ago | (#19512837)

.. the planet is defended by 5 lions.

I don't understand this 'dwarf planet not planet' (0)

Anonymous Coward | more than 7 years ago | (#19512867)

Surely a dwarf planet is a planet, in the same way that a yellow car is a car. Maybe they meant to call Eris a "planetoid"?

Ah, astronomers... (4, Funny)

UbuntuDupe (970646) | more than 7 years ago | (#19512871)

Remember: just now they figured out which of Eris and Pluto is more massive...

but they also know the internal density distributions of extrasolar planets that barely take up a pixel on the most powerful telescopes.

Re:Ah, astronomers... (1)

Pausanias (681077) | more than 7 years ago | (#19513337)

LOL, too true.

With the mass of Eris and Pluto, it was a relatively high precision measurement (for astronomers anyway). For the internal density profiles of planets, it's not a direct measurement---it's modeling of the data to argue for consistency with various models. So, to put it more accurately, they just measured the masses of Eris/Pluto correctly; but for the extrasolar planets, they considered various models consistent with the data and showed which one is most likely.

Generally the public doesn't know/care about that particular distinction. And that's good for funding.

Pluto had remained a planet (0, Flamebait)

nurb432 (527695) | more than 7 years ago | (#19512903)

It still is. And anyone who disagrees is an idiot.

Re:Pluto had remained a planet (1)

philpalm (952191) | more than 7 years ago | (#19513069)

Biased American astronomers prefer to claim Pluto as a planet(since it was an American discovery). Lazy students prefer to remember less names. Slash dot prefers to keep putting salt in The Wounds of those astronomers who preferred to keep Pluto as a planet.

Now calling me an idiot would make you feel better go ahead. At least I am not a Rocket scientist....

Re:Pluto had remained a planet (1)

nurb432 (527695) | more than 7 years ago | (#19513153)

If you believe it is not a planet, then you have earned the title. If you accept that it IS a planet, then no 'name calling' will apply.

Pluto never should have been a planet (1)

theWrkncacnter (562232) | more than 7 years ago | (#19512915)

It's funny how people get so worked up about Pluto not being a planet. The fact is that it should have never been a planet in the first place. Scientists did a similar thing back in the 1800s when the decided not to call all of the asteroids between Jupiter and Mars planets. If we kept calling Pluto a planet, then we'd have to add all the other Kuiper belt objects. There's a very good Scientific American article here [sciam.com] that explains the whole thing. If you're still crying about Pluto not being a planet you should probably read it.

Re:Pluto never should have been a planet (1)

khallow (566160) | more than 7 years ago | (#19513215)

I don't see the dust settled on this issue. Looks to me like the IAU will have to revisit this issue at the next meeting in 2009 (especially since the definition isn't well-defined). Who knows what a planet will be after that? And what's your reasoning for claiming Pluto "should" have never been a planet? In the case of the asteroids, four were found in quick succession. So it was known almost from the begining that there were several asteroids. More were found around thirty years later. In comparison, Pluto was unique from the 30's until the 90's. So I don't think your accusation is fair to the original decision to make Pluto a planet.

I don't see a strong reason to keep Pluto a planet given that there's probably a large group of objects larger than it, that we haven't discovered yet. But the IAU decision was hasty and sloppy and the decision will certainly be revisited.

Re:Pluto never should have been a planet (1)

mdwh2 (535323) | more than 7 years ago | (#19513355)

Whether or not the asteroids we found quickly in succession or not is beside the point - the first few were still labelled planets for about 50 years, before they decided to reclassify them.

Re:Pluto never should have been a planet (2, Insightful)

Bongo Bill (853669) | more than 7 years ago | (#19513377)

This is the reason that people think Pluto should be a planet:

Did you learn it before you were ten years old? If yes, it can not ever change.

Re:Pluto never should have been a planet (0)

Anonymous Coward | more than 7 years ago | (#19513691)

If I'm crying, how can I read the article, you insensitive clod?

I'm no astrophysicist... (1)

Mordok-DestroyerOfWo (1000167) | more than 7 years ago | (#19512923)

But I've always defined a planet as a solid body whose gravitational field was sufficient to force it into a spherical shape and strong enough to maintain some sort of atmosphere. I suppose that would kick Mercury out of the planet club as well, but we would welcome Titan with open arms.

Re:I'm no astrophysicist... (1)

ZombieWomble (893157) | more than 7 years ago | (#19513269)

Any definition based on atmosphere isn't very useful, as the ability of a planet to retain an atmosphere is not determined solely by its own properties, but also by its distance from the sun. Indeed, by your definition Pluto and a few other moons are planets while Mercury is not, as although Mercury is significantly larger, it is also significantly hotter.

Pluto and its 'Moon' - Really A Broken Ball of Ice (1)

rogerborn (236155) | more than 7 years ago | (#19513041)

Consider the image of a hard packed snowball, broken into two unequal parts.

So goes the latest theory about this 'planet' Its size, if the two pieces were weighed together,
would make it a considerable planet in its own right. But if it is broken in two because it is
made of mostly ice and lighter elements, would we consider it to be a planet at all or just
another large body out in the Ort Cloud?

"Sorry. No Refunds."

Everyone? (2, Informative)

KenAndCorey (581410) | more than 7 years ago | (#19513137)

Everyone still considered Pluto a planet then [in 2005]

What are you talking about? I haven't considered it a planet since I took astronomy in the early 90's. Of course the public didn't have a clue, but a lot of astronomers knew Pluto shouldn't be considered a (regular) planet.

Mistaken assumption (4, Interesting)

aafiske (243836) | more than 7 years ago | (#19513203)

I think the mistake in the logic here is assuming that Pluto was kept a planet because it had a certain mass, or orbit, or whatever. Pluto was kept a planet because of tradition, in essence. If it were found today, I don't think it would be considered one. So no opening of the floodgates for every hunk of rock that has some number that measures larger than Pluto.

Re:Mistaken assumption (1)

ZombieWomble (893157) | more than 7 years ago | (#19513307)

While the basic gist of your comment is correct, I think the mistake in your logic is assuming Pluto is still a planet.

uhhhhhhh (1)

dreemkill (170748) | more than 7 years ago | (#19513241)

yeah, uhh..since when did size determine if something is a planet?

Dwarf Planet is so Politically Incorrect... (4, Funny)

sconeu (64226) | more than 7 years ago | (#19513301)

Pluto and Eris prefer the term "Gravitationally Challenged".

Re:Dwarf Planet is so Politically Incorrect... (-1, Troll)

Anonymous Coward | more than 7 years ago | (#19513433)

Wow, a joke about political correctness.

Next are you going to tell me about how fat my mother is to capitalize on the rest of the early 90's stand up comedy wave you are riding on?

GOAT (-1, Troll)

Anonymous Coward | more than 7 years ago | (#19513305)

Re:GOAT (1, Funny)

Anonymous Coward | more than 7 years ago | (#19513727)

That's not Eris or Pluto...it appears to be a black hole.

Had to be said... (1)

schattenteufel (926231) | more than 7 years ago | (#19513375)

"Mass of Dwarf Planet Eris 27% Greater than Pluto... surely Eris would be considered the 10th planet." If that's all it took, then my ex-girlfriend would be classified as a planet as well!

Re:Had to be said... (1)

RedElf (249078) | more than 7 years ago | (#19513581)

If that's all it took, then my ex-girlfriend would be classified as a planet as well!
That's some, uh, interesting taste you have in women there.

Have we learned nothing? (1)

halovaa (774219) | more than 7 years ago | (#19513395)

Wasn't the Trojan War started because she wasn't invited to a party? And now, not only is she not invited to join the planets...but we're calling her FAT?

Apparently... (1)

Loconut1389 (455297) | more than 7 years ago | (#19513723)

...for Astronomers, Size Matters.

spoiler alert! (2, Funny)

kaizokuace (1082079) | more than 7 years ago | (#19513863)

Eris dies.
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