57 replies to this topic

[Antonio2014]

Huh? AFAIK, there is no evidence of any planet X.

 

Edit: Oh, do you refer to this? http://iopscience.io...4-6256/151/2/22 You are fast I didn't know about it yet. I will take a look at it soon.

Edited by Antonio2014, 21 January 2016 - 09:33 AM.

[shifter]

Yeah that's the one. Not actually observed but if true they have no problem calling it a planet despite clearly failing the made up criteria that 'demoted' Pluto.

[Antonio2014]

It's very exciting news, but not an actual discovery, since it hasn't been directly observed. Indeed, it should have been observed already by WISE or 2MASS, probably. A gas giant at that distance should be detectable in the infrared.

 

Oh, I see that you posted another comment.

 

Yeah that's the one. Not actually observed but if true they have no problem calling it a planet despite clearly failing the made up criteria that 'demoted' Pluto.

 

I think it clearly satisfies the current criteria for planets, if it exists and has the orbital features that the article says.

 

Additional info here: http://www.caltech.e...th-planet-49523

 

Particularly:

 

Unlike the class of smaller objects now known as dwarf planets, Planet Nine gravitationally dominates its neighborhood of the solar system. In fact, it dominates a region larger than any of the other known planets—a fact that Brown says makes it "the most planet-y of the planets in the whole solar system."

Edited by Antonio2014, 21 January 2016 - 12:28 PM.

[Turnbuckle]

Yeah that's the one. Not actually observed but if true they have no problem calling it a planet despite clearly failing the made up criteria that 'demoted' Pluto.

 

 

Exactly. And if they went strictly by their own ad hoc rules, they'd have to demote Neptune as well as it's failed to clear out its orbit of Pluto.

[PWAIN]

If you see the orbits of this new 'planet' and the other rocks that they claim would also have to be called planets, you would realise how ridiculous it all is. We should just define a planet as having a certain orbit and then Pluto would be a planet and all the other rubbish would just be space rocks.

Edited by PWAIN, 21 January 2016 - 12:42 PM.

[PWAIN]

See the image of the orbits in this article here. A real eye opener I think.

http://www.sciencema...gn=planetx-1987

[Antonio2014]

Exactly. And if they went strictly by their own ad hoc rules, they'd have to demote Neptune as well as it's failed to clear out its orbit of Pluto.

 

Nope. Pluto is not sharing neigbourghood with Neptune. On the contrary, Neptune determines Pluto's orbit and keeps Pluto apart from itself: https://en.wikipedia.org/wiki/Plutino

 

And, of course it isn't ad hoc, no matter how many times you repeat it. It follows the same principles by which asteroids were no longer considered planets almost two centuries ago.

Edited by Antonio2014, 21 January 2016 - 12:49 PM.

[Turnbuckle]

 

Exactly. And if they went strictly by their own ad hoc rules, they'd have to demote Neptune as well as it's failed to clear out its orbit of Pluto.

Nope. Pluto is not sharing neigbourghood with Neptune. On the contrary, Neptune determines Pluto's orbit and keeps Pluto apart from itself: https://en.wikipedia.org/wiki/Plutino

 

 

 

A specious argument. Pluto crosses Neptune's orbit (or vice versa), so that is one very big matzo ball in Neptune's lap. The IAU gets away with it by failing to specify what "clearing the neighborhood" actually means. 

[Antonio2014]

The Moon also crosses Earth's orbit. Is it a planet?

 

 

 

Edited by Antonio2014, 21 January 2016 - 02:21 PM.

[Turnbuckle]

The Moon also crosses Earth's orbit. Is it a planet?

 

 

 

 

Satellites are ruled out as planets, but your question misses the point rather badly. You should have asked, does the moon crossing Earth's orbit mean that Earth is a dwarf planet? And the answer is no, because only bodies orbiting the sun are considered, not those orbiting other bodies.

[platypus]

The orbits of Pluto and Neptune do not actually cross:

 

http://www.livescien...it-neptune.html

 

 

[Turnbuckle]

Platypus is correct. The actual distance between the orbits of Pluto and Neptune is several AU, but that raises the question of "neighborhood" and how close you actually have to be. How close does Pluto's orbit get to other bodies in the Kuiper Belt, for instance? I've never seen any data on this, and I rather doubt there is any. 

 

Edit: If one looks at the planets in the plane of the ecliptic, neither Pluto nor Neptune meet the criteria as their orbits cross. If one looks in 3-D, however, their orbits are 8 AU apart at the closest. But that means we have to look at "neighborhood" as an elliptical torus with a certain cross-sectional radius, and demand that it be cleared out to qualify. But what radius? The smallest distance between 2 recognized planets is between Venus and Earth, so we could use that as the standard minimum radius--0.28 AU. In which case Pluto would fit the definition of planet unless a body could be found orbiting within that distance of Pluto's orbit. But no one knows of one, do they? Or we could expand the radius for objects in the outer solar system and say the minimum radius is the closest distance between Pluto and Neptune--the previously mentioned 8 AU. But even then, can anyone name any body that would come closer to Pluto's orbit?

Edited by Turnbuckle, 21 January 2016 - 04:19 PM.

[Antonio2014]

Satellites are ruled out as planets, but your question misses the point rather badly. You should have asked, does the moon crossing Earth's orbit mean that Earth is a dwarf planet? And the answer is no, because only bodies orbiting the sun are considered, not those orbiting other bodies.

 

It's you who is missing the definition rather badly. First learn what clearing the neighbourhood means and then you can start talking about what a planet is.

Edited by Antonio2014, 21 January 2016 - 06:04 PM.

[Antonio2014]

Platypus is correct. The actual distance between the orbits of Pluto and Neptune is several AU, but that raises the question of "neighborhood" and how close you actually have to be. How close does Pluto's orbit get to other bodies in the Kuiper Belt, for instance? I've never seen any data on this, and I rather doubt there is any.

 

Your ignorance is not proof of absence of data.
 

[Turnbuckle]

 

Satellites are ruled out as planets, but your question misses the point rather badly. You should have asked, does the moon crossing Earth's orbit mean that Earth is a dwarf planet? And the answer is no, because only bodies orbiting the sun are considered, not those orbiting other bodies.

 

It's you who is missing the definition rather badly. First learn what clearing the neighbourhood means and then you can start talking about what a planet is.

 

 

From your link--

 

A large body which meets the other criteria for a planet but has not cleared its neighbourhood is classified as a dwarf planet. This includes Pluto, which shares its orbital neighbourhood with Kuiper belt objects such as the plutinos. The IAU's definition does not attach specific numbers or equations to this term, but all the planets have cleared their neighbourhoods to a much greater extent than any dwarf planet, or any candidate for dwarf planet.

 

 

 

 

So "clearing the neighborhood" is an undefined concept, arbitrarily applied. Even so, its applicability is disputed--

 

 

Stern, currently leading the NASA New Horizons mission to Pluto, disagrees with the reclassification of Pluto on the basis that—like Pluto—Earth, Mars, Jupiter and Neptune have not cleared their orbital neighbourhoods either. Earth co-orbits with 10,000 near-Earth asteroids (NEAs), and Jupiter has 100,000 trojans in its orbital path. "If Neptune had cleared its zone, Pluto wouldn't be there", he now says.

 

[Antonio2014]

I'll let Mike Brown to reply to you:

 

The IAU definition of planet includes the clunky phrase that it has to "clear its orbit." Really, this phrase is just an attempt to explain the concept that planets are the gravitational dominant things of planetary system and that one of the ways they display their gravitational dominance is by pushing around everything in their path. Overly literal critics of the IAU definition will insist that because Jupiter has asteroids which co-orbit with it (the Jupiter Trojans) that Jupiter is not a plane by this definition, etc. etc., but that is simply a problem with the clunkiness of the statement of the definition, not of the underlying concept.

 

(Emphasis mine.)

 

http://www.findplane...ine-planet.html

 

Oh, and next time, try to read more than two paragraphs of the link someone shows you:

 

The phrase may be derived from a paper presented to the general assembly of the IAU in 2000 by Alan Stern and Harold F. Levison. The authors used several similar phrases as they developed a theoretical basis for determining if an object orbiting a star is likely to "clear its neighboring region" of planetesimals, based on the object's mass and its orbital period.^[2]

 

he phrase refers to an orbiting body (a planet or protoplanet) "sweeping out" its orbital region over time, by gravitationally interacting with smaller bodies nearby. Over many orbital cycles, a large body will tend to cause small bodies either to accrete with it, or to be disturbed to another orbit, or to be captured either as a satellite or into a resonant orbit. As a consequence it does not then share its orbital region with other bodies of significant size, except for its own satellites, or other bodies governed by its own gravitational influence. This latter restriction excludes objects whose orbits may cross but that will never collide with each other due to orbital resonance, such as Jupiter and its trojans, Earth and 3753 Cruithne, or Neptune and the plutinos.^[2]

 

Stern-Levison's Λ

In their paper, Stern and Levison sought an algorithm to determine which "planetary bodies control the region surrounding them".^[2] They defined Λ (lambda), a measure of a body's ability to scatter smaller masses out of its orbital region over a period of time equal to the age of the Universe (Hubble time). Λ is a dimensionless number defined as

where M is the mass of the body, a is the body's semi-major axis, and k is a function of the orbital elements of the small body being scattered and the degree to which it must be scattered. In the domain of the solar planetary disc, there is little variation in the average values of k for small bodies at a particular distance from the Sun.^[3]

 

If Λ > 1, then the body will likely clear out the small bodies in its orbital zone. Stern and Levison used this discriminant to separate the gravitionally rounded, Sun-orbiting bodies into überplanets, which are "dynamically important enough to have cleared its neighboring planetesimals", and unterplanets. The überplanets are the eight most massive solar orbiters (i.e. the IAU planets), and the unterplanets are the rest (i.e. the IAU dwarf planets).

 

Edited by Antonio2014, 22 January 2016 - 11:59 AM.

[Turnbuckle]

Yes, I did read the link, and I saw it for what it was, an attempt to create a mathematical basis for kicking Pluto (and the newly discovered bodies in the Kuiper belt) out of the planet club. Several have created discriminates, but none have been adopted, and that was not the basis of the IAU voting.

 

 

[mikeinnaples]

So yeah the new planet ..... the only thing that I ask is that we name it Nibiru just to mess with people

[Antonio2014]

Where to search for Planet Nine: http://www.findplane.../blog-page.html

[Kinesis]

Given we now know that Pluto is a geothermically active and colourful world with unique topography and is not just a flat icy ball of rock is there any talk or chance do you think of upgrading it back to a regular planet basis? When someone asks me how many planets are on the solar system, I will always include Pluto. What do you think? Do you think Pluto should be our 'ninth planet?

Yes. Let's take a step back and look at what happened. The word "planet" was originally introduced to distinguish these bodies from the "fixed" stars. The word signified a "wanderer" that moved from observation to observation. It still means something that revolves around something else, as in a "planetary" gear. So Pluto patently meets the definition.

So what changed? Pluto sure didn't. Rather organized astronomy decided to try and change the meaning of the word "planet". Apparently because Pluto is qualitatively different from the other bodies we call planets. But even with this excision, there remains considerable heterogeneity among the remaining members of the planetary family. Some are small and rocky, others giant and gassy. What next? Are we going to throw out Jupiter, Saturn, Uranus, and Neptune because they are not sufficiently like Mercury? Or maybe declare they are the only true planets and that Earth is actually an "aqueous terrestreoid"?

The whole thing smacks of scientific sophistry. Words mean what they mean because that's what people think they mean, not because of bureaucratic fiat.

A rose is still a rose and Pluto is still a planet.

[Antonio2014]

Yes. Let's take a step back and look at what happened. The word "planet" was originally introduced to distinguish these bodies from the "fixed" stars.

 

And the word 'asteroid' was introduced to distinguish planets from clouds of objects that didn't cleared their neighbourhood. Pluto was named a planet because no other bodies were known in his neighbourhood. When hundreds were found, his name was changed. Ceres was named a planet because no other bodies were known in his neighbourhood. When hundreds were found, his name was changed.

 

It's boring to explain the same simple, elementary thing again, again and again...

Edited by Antonio2014, 22 April 2016 - 01:58 PM.

[Kinesis]

 

Yes. Let's take a step back and look at what happened. The word "planet" was originally introduced to distinguish these bodies from the "fixed" stars.

 

And the word 'asteroid' was introduced to distinguish planets from clouds of objects that didn't cleared their neighbourhood. Pluto was named a planet because no other bodies were known in his neighbourhood. When hundreds were found, his name was changed. Ceres was named a planet because no other bodies were known in his neighbourhood. When hundreds were found, his name was changed.

 

It's boring to explain the same simple, elementary thing again, again and again...

 

 

The last statement assumes that those who disagree are simply not in possession of the facts.  But there is no evidence cited for this.  It is possible we simply don't agree that these facts override others such as the fact that Pluto historically and literally is a planet.

 

Suppose the language must be revised every time new information comes to light.  What other consequences might the same kind of reasoning have?  The constellation Orion "derives its name from from Greek mythology in which Orion was a gigantic, supernaturally strong hunter".  But it's not really a hunter, is it?  We now understand that it's a formation of stars that are not really even near each other and only fancifully resemble a hunter from the viewpoint of Earth.  But as far as we know there is no serious effort among the astronomic cognoscenti to stop people from calling it Orion.  Or even to deconstruct the word constellation and declare that it is not really even a real grouping of stars and that therefore the notion of a constellation is merely illusory and should be banished from the lexicon.  As another example, a "triglyceride" is technically a triacylglycerol, but it is still called a triglyceride nevertheless.  Language is replete with examples of words whose meaning derives not from technical nuance but from historical usage and convention.

 

According to https://en.wikipedia.org/wiki/Asteroid, "Asteroids are minor planets, especially those of the inner Solar System.".  If these objects are minor "planets", then certainly Pluto is as well.  From the same authority, we also have "The first asteroid to be discovered, Ceres..." indicating that in fact Ceres too is a planet.  It is a "wanderer" and it certainly revolves around something else, so why not.  Does that mean that it's not an asteroid?  Maybe the term "asteroid" itself should be abolished and replaced with "planetoid", since they're not really little stars.  If I recall correctly an attempt to revise the language along those lines failed too.
 

It truly is possible to be in full possession of the facts, and still correctly refer to the constellation Orion, triglycerides in the blood, and to the planet Pluto.

[Antonio2014]

If you had read the previous posts, you would know the facts. Also, you would know that the same thing happened more than a century ago. So yes, it's clear that you didn't have the facts.

 

Suppose the language must be revised every time new information comes to light.
 

It happens all the time. For example, many scientific names of living beings have changed. Even whole taxonomical families have been renamed or even dissapeared, being fused with other families or split in several parts. Diseases' names also change from time to time, when we know more information. They are separated into different diseases, or simply renamed.

 

For example:
 

In the 1970s the World Health Organization defined stroke as a "neurological deficit of cerebrovascular cause that persists beyond 24 hours or is interrupted by death within 24 hours",^[12] although the word "stroke" is centuries old. This definition was supposed to reflect the reversibility of tissue damage and was devised for the purpose, with the time frame of 24 hours being chosen arbitrarily. The 24-hour limit divides stroke from transient ischemic attack, which is a related syndrome of stroke symptoms that resolve completely within 24 hours.^[2] With the availability of treatments which can reduce stroke severity when given early, many now prefer alternative terminology, such as brain attack and acute ischemic cerebrovascular syndrome (modeled after heart attack and acute coronary syndrome, respectively), to reflect the urgency of stroke symptoms and the need to act swiftly.^[13]

 

https://en.wikipedia.org/wiki/Stroke

 

The constellation Orion "derives its name from from Greek mythology in which Orion was a gigantic, supernaturally strong hunter".  But it's not really a hunter, is it?

 

Huh? Can't you distinguish a common noun from a proper noun? Nobody is proposing to change the name 'Pluto'...

 

Or even to deconstruct the word constellation and declare that it is not really even a real grouping of stars and that therefore the notion of a constellation is merely illusory and should be banished from the lexicon.

 

Every current profesional astronomer in the world thinks that constellations aren't really even a real grouping of stars. The nomenclature is only kept by astronomers to name regions in the sky, not star groupings.

 

Another example, nobody today calls Andromeda a nebula. It's now called a galaxy, because we now know that it's formed by many stars, like our own Milky Way ('galaxias' is 'milk' in Greek). Furthermore, the first name for galaxies where 'island universes'. Another name that changed.

 

"Asteroids are minor planets, especially those of the inner Solar System.".  If these objects are minor "planets", then certainly Pluto is as well.

 

Pluto is a minor planet but not a planet. That's another fact that you don't know and that is also mentioned in the thread.

 

That's another reason why it's so BORING to reply to you.

 

Edited by Antonio2014, 22 April 2016 - 06:50 PM.

[Kinesis]

Things you can do if you're losing a debate

Sometimes you might find yourself having taken an untenable position and fear others may be noticing. If your priority is appearances, there are a few tactics you can use to distract attention.

1) One time-worn technique is ad hominem. If you don't have the facts and logic to tear down your opponent's reasoning, the next best thing is to try and tear down your opponent. You could insinuate that if he doesn't agree with your argument, he's just hasn't read it. Or if his argument is solid, you could always try and dismiss it as boring. If you're obnoxious enough, maybe other posters will just decide there isn't enough sport in the debate to continue, and without the opposing arguments you can sustain the illusion that you are right. On the downside, that only works if readers don't examine the arguments very closely. Not only that, but if you succumb to this temptation very often you might wind up with scads of negative reputation points.

2) If your thesis is particularly endangered by a post, you can vote it down. This has the advantage of allowing you to hide in anonymity and it's easy because you don't have to have to defend your action. Not only that, but by doing this you put others on notice that if they post a cogent rebuttal, they risk accumulating negative points. This way you can discourage others from posting rebuttals to your argument and let it look like they no longer disagree. Although it is cheap, this has the disadvantage of being an abuse of the point system.

3) You can post distracting graphics in an attempt to divert attention from the the issue, where your weakness is. This way only people who take the time to actually take time read through and consider the arguments on their merits will notice your case is lost. The only problem is it looks silly.

I'm glad you didn't try any of those things, because they not only would look bad but would drag down the average posting quality of a good forum.

Things you can do if you've lost a debate

4) You could keep trying 1)-3), or you could do the grown-up thing and just concede. Since your opponents are correct, all you need to do is say pretty much the same thing they’ve been saying all along.

Pluto is still a planet

Pluto is a minor planet

Congratulations! You made the right choice.

[Antonio2014]

So... that's what you are doing? So boring...

[shifter]

The problem with the 'dwarf' tag is people automatically think of it as a demotion or less of a planet rather than a different classification. In changing the definition of the word planet to include 'must have cleared it's neighbourhood' kind of rules out 'Planet 9' because it would be lodged deeply inside the Kuiper belt. It essentially ruled that anything inside the Kuiper belt (or spends any time in there) could not be a planet because the neighbourhood there is not clear. Essentially then, the new classification would make Planet 9 despite its alleged size to be a dwarf.

 

We got a bunch of eggheads into a room to decide whether Pluto could still fit the definition of a 'planet'. At that time Pluto was thought to be a chunk of uninteresting ice. Still, many voted to keep it as is but not enough. How many of those eggheads would have voted against this new definition to exclude Pluto if they knew then what they know now. That it is a geological active / diverse world with an atmosphere, 5 moons and a warm core.

 

Rather than deliberately change the wording of a definition in any way possible to exclude Pluto because heaven forbid people are told to remember more than 10 names in a solar system. If Pluto however was as big as Mars, Kuiper Belt neighbourhood or not, nobody would have said 'lets change the definition so we can exclude it'. Size always has mattered :(

 

Everywhere you look now, it says there are 8 planets in the solar system. We just had a close look at one planet out there which may yet be the most interesting of them all (ice volcanoes?!) But unless people actually look for it, we have a generation of kids that will never be taught about it (Doubtful these dwarf planets will be in any teachers syllabus and they aren't in usual 'guides to the solar system). We haven't even seen this 'Planet 9' and its pure existence is in debate yet it's already classified as a planet! (Hence 'Planet' 9)

 

People can hate on Pluto all they want now, but in a few billion years when the sun swells into a red giant, it may be the only terrestrial world supportive to life in the solar system. (However its elliptical orbit is a bit annoying which would make extreme temperature variations throughout its yearly orbit). I think we should use Pluto as our backup doomsday vault like we have in Svalbard where we store all the seeds of every plant.

 

 

[Turnbuckle]

 

 

Everywhere you look now, it says there are 8 planets in the solar system. 

 

 

Yeah, isn't it amazing how quickly the population falls into line? And some get truly hostile when anyone goes against the group think, as we see here.

 

I'd rather see a definition that eliminated the ad hoc "clearing its neighborhood" restriction in exchange for "active geologically or atmospherically." This would eliminate Mercury and all totally frozen planets further out than Pluto. These totally frozen bodies would become "nascent planets," while Mercury and Ceres would become "dead planets," or "lunar planets." Or they could all become "dead planets" if they aren't active. Then, when we discovered Mercury had active volcanoes, we could promote it back into the realm of the living.

Edited by Turnbuckle, 26 April 2016 - 01:35 PM.

[AlephNull]

Can you imagine the hue and cry that would rise up if it turned out that kids in elementary school didn't have to just memorize nine planets, but rather nearly twenty?

 

I figure the IAU killed Pluto's planetary status out of consideration for the inevitable exasperation that would arise from the education system than anything else.