Astronomers Spot Most Distant Object In the Solar System (sciencemag.org) 85
sciencehabit writes: Astronomers have found the most distant known object in our solar system, three times farther away than Pluto. The dwarf planet, which has been designated v774104, is between 500 and 1000 kilometers across. It will take another year before scientists pin down its orbit, but it could end up joining an emerging class of extreme solar system objects whose strange orbits point to the hypothetical influence of rogue planets or nearby stars.
In other planetary science news, UCLA professor Jean-Luc Margot has proposed a new definition of the term "planet" which would allow for the inclusion of exoplanets. His metric is laid out in an academic paper available at the arXiv.
i identify as a planet (Score:5, Funny)
Re: i identify as a planet (Score:5, Funny)
You were born a moon and, by God, you'll act like it! And enough of this filthy talk of astroid drilling, it's unnatural!
Re: i identify as a planet (Score:2)
That's no moon...
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Re:i identify as a planet (Score:4, Funny)
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You could probably make big bucks following him around with a tuba.
Re: i identify as a planet (Score:1)
I'm often persecuted for having an eccentric orbit.
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Is this part of the anti fat shaming movement?
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2620 can't come soon enough.
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You can't be a planet, which is nobody's fault, not even the IAU. But we will fight the oppressors for your right to be a planet.
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Must...Resist...Chris...Christie...Jokes
Does this mean??! (Score:1)
We can have Pluto again?
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Nope. A tiny fraction of a group who is overwhelmingly not planetary scientists has spoken and made their internally-inconsistent definition. It stands until they revoke or alter it.
Re: Does this mean??! (Score:4, Informative)
In the words of Wikipedia, "Citation needed". The planetary scientists at the IAU meeting had been by and large pursuing a definition involving a body reaching gravitational equilibrium. They've also been leading the charge to get it overturned. There are numerous published papers by planetary scientists who continue to refer to large KBOs and the like as planets. The New Horizons team is particularly notable in continued references to them as planets.
The vote passed via a non-randomly-selected 4% of the IAU's membership who were - as previously mentioned - overwhelmingly not planetary scientists. Letting people who study stars (by the way, a "dwarf star" is still a "star") decide what a planet is is just plain stupid - it's not their field of expertise. The first draft proposal indeed went with the planetary scientists' version - hydrostatic equilibrium being the criteria, and was confirmed on the 18th, with intent to vote on the 24th. Many people left the IAU meeting thinking that this was the version that was going to be voted on, and since they supported either having it or no definition at all, they didn't need to be there. The proposal was changed however on the 22nd. Due to dischord among the IAU members there were "secret" negotiations held on the proposal on the evening of the 23rd, and it looked increasingly unlikely that anything was going to be agreed upon. But then they came out with the current version on the 24th - after most of the membership had left - and had it voted on during the same day, when most of the people remaining were the ones who had been fighting against the planetary scientists' equilibrium definition. They furthermore reverted the standard rules which only allow people in a specific field to vote on matters related to their field, declaring the definition of planet a matter applicable to the whole union, so that everyone, not just planetary scientists, could vote.
There are not little complaints about "the exact wording" - do I really need to go into a breakdown of all of the arguments against it?
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There are not little complaints about "the exact wording" - do I really need to go into a breakdown of all of the arguments against it?
No, but if you are going to demand citation from others about what the majority of planetary scientists think, you can't conveniently ignore that yourself.
Do you have any citation that the vote was not representative, and that it would have changed the status of Pluto if any of that stuff you complain about was different? And finding a few planetary scientists that are upset about the definition is not the same as saying a majority care to vote for/against it.
It doesn't matter how quirky the voting was or
Re: Does this mean??! (Score:4, Interesting)
I described the process that led up to the vote, which you can easily read anywhere on the net. You can also readily find no shortage of planetary scientists complaining about it on the net. If there's any specific fact you disagree with, state it and I will reference it for you.
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But none of this matters. No matter what humans call Pluto or how we classify it. whether we fight wars about it on /. or on a battlefield with guns, none of this matters whatsoever to the astronomical object we call Pluto. Every single atom it's made of will carry on the same regardless of what we call it, or whether indeed humans had ever managed to find out it was there at all.
So go on and argue about it. Someone will eventually win. And it will still make no difference at all. Pluto will carry o
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What are you? I am a meat Popsicle! (Score:2)
If they had any sense, they might agree that there are probably hundreds of billions of objects out in space, some of which have the properties of the traditional view of a planet, and also the properties of of what is wasn't
It's so ridiculously easy (Score:4, Insightful)
.. to make up a formula to say what you want it to say for data like this.
Here, want an alternative formula to declare the 8 IAU "planets" as planets as well as exoplanets but exclude the IAU "dwarf planets", without using any of the terms he uses, and to be able to classify 100% (rather than the 99%) of exoplanets?
MeanDistanceFromTheSun / DiscoveryYear ^5 > 0.21mm/y^5
It's a functional formula. Does this mean that it's a reasonable formula? Of course not; it has no connection with the reality of what they actually are. But you know what? Neither does his or the IAU's "cleared the neighborhood" concept. There are no credible planetary models that show for example that Mars cleared its own neighborhood. While they differ on the details, they all agree that Jupiter cleared it (and cleared most of the debris from the inner solar system in general, with some help from Saturn). Neptune has (despite its distance from the sun) orders of magnitude more orbit-clearing power than Mars yet nonetheless contains multiple objects a couple percent the size of Mars in its "neighborhood". Is Mars not a "planet"?
I have a giant list of reasons why the IAU decision is poor and unscientific, but no need to post it again.
Re: It's so ridiculously easy (Score:4, Interesting)
Mars has a tiny fraction the Stern-Levison parameter of Neptune, and Neptune hasn't gotten rid of large bodies from its "neighborhood" (they're small compared to Neptune, but not compared to Mars).
It's not a "problem" at all. The definition that most planetary scientists wanted the IAU to choose (if they felt the need to pick one at all) was hydrostatic equilibrium, meaning there would be dozens of planets. Achieving a rough hydrostatic equilibrium is a very meaningful dividing line - it means differentiation, mineralization processes, alteration of primordial materials, and so forth. It's also often associated with internal heat and, increasingly as we're realizing, a common association with subsurface fluids. In short, a body in a category of "not having achieved hydrostatic equilibrium" describes a body which one would study to learn about the origins of our solar system, while a body in a category of "having achieved hydrostatic equilibrium" describes a body one would study, for example, to learn more about tectonics, geochemistry, (potentially) biology, etc. By contrast, a dividing line of "clearing its neighborhood" - which isn't actually what half of the planets in our solar system have done - says little about the body itself.
And yes, there are many reasons why the whole process was grossly unscientific. I've first already covered the voting process above, which is absurd, especially in a day where they could have handled such a thing online. There's the obvious criticism of it being sun-centered, having no clear definition on what defines a "neighborhood" or "cleared", the pseudoscience of the planets all having cleared their own neighborhoods, the lie about how they planned to review further "dwarf planets" for inclusion (they haven't), the comparative inconsistency (really, Earth is more like Jupiter than it is like Pluto?), the atrocious name where a "dwarf X" isn't an "X", and on and on. But these are just minor points.
First off, the primary reason cited by virtually every scientist I've seen interviewed about their vote in favor of an exclusive standard over an inclusive standard is along the lines of, "It would be too hard for schoolchildren to memorize the names of all of them". This is such a blatantly unscientific standard that it doesn't even bear going into, and leads to absurd consequences when applied to other fields, such as the AMA declaring that there's only 8 bones in the human body and all others are "dwarf bones" that aren't real bones, or the USGS declaring that there's only 8 rivers in the world and all others are "dwarf rivers" that aren't real rivers, all for the purpose of making things easier for students to memorize. They decided that they wanted schoolchildren to be able to memorize the names of all the planets around the sun, and then contrived a definition of "planet" to try to make that happen. This is not science, it's idiocy.
Then there's the basic issue of scientific categorizations altogether. In every scientific field, the universe continually presents those making discoveries with a wide range of diversity. This is almost universally accepted in an inclusive manner, subdividing groups into subgroups, and subdividing those further. We will continue to find new types of planetary bodies in a wide range of diversity - large terrestrial planets, dwarf-scale planets, gas giants, ice giants, hot jupiters, super-earths, water worlds, supercomets, extremely large bodies orbiting as moons, planets without parent stars, and so forth. Rather than trying to hide diversity, science is supposed to embrace it.
Then there's the issue of the timing. For most of the history of humankind's knowledge of Ceres and Pluto, we have
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Forget it, he's rolling.
Re: It's so ridiculously easy (Score:4, Informative)
Mars does not gravitationally dominate its neighborhood and force things into resonance with it. The vast majority of asteroids are locked into resonances with Jupiter, not Mars. There's only about 1500 known asteroids, the Polana group, which are locked into a 2:1 resonance with Mars (Mars also has 4 trojans which do not appear related to each other).
The Stern-Levison parameter is based around the principle of scattering small bodies, bodies far smaller than the parent, which can be scattered on a single pass at distance b to an angle greater than or equal to a given value. Pluto is a "small body" compared to Neptune, but not so compared to Mars. And Mars's Stern-Levison parameter is, again, far less than Neptune's.
The claim that "a value of over 900 for Mars is more than enough to clear out other bodies" is false even if we ignore this troublesome "small body" aspect. Again, read the Stern-Levison paper. The value of 900 for Mars comes from assuming a scattering angle of one radian from its approach angle, which hardly means ejection or single-pass domination. It assumes 12 billion years for the age, several times older than the solar system. It relies on the "small bodies" having high eccentricities, which would probably not be the case in a gas-giant-less solar system - the lower the eccentricity, the far weaker the scattering potential. And of course, they assume actual small bodies - typical asteroid sizes.
Interestingly enough, I would have been happy with the classification actually laid forth in Stern-Levison (2002). They proposed a size/composition matrix similar to that of stars, with all objects large enough to be in hydrostatic equilibrium included. The mass would be grouped into "subdwarf" (Ceres, Pluto, Charon, etc), "dwarf" (Mercury, Venus, Earth, Mars), "subgiant" (Uranus, Neptune, Saturn), "giant" (Jupiter), and "supergiant" categories, while the composition grouped into "rock" (terrestrial planets, asteroids), "ice" (KBOs, uranus, neptune), and "hydrogen" (saturn, jupiter). So for example Jupiter would be a "hydrogen giant planet". Pluto would be a "rocky subdwarf planet". Titan would be a "icy subdwarf satellite". Etc.
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Oh, and while we're at it, according to the IAU's definition, Jupiter shouldn't be a planet. They define planets as bodies that orbit the sun that have cleared their neighborhoods. Jupiter does not orbit the sun. It orbits the Sol-Jupiter barycentre, which is outside of the sun - the sun and Jupiter roughly co-orbit this point.
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But few orbit a barycentre *outside either body*. When they're the same type of object we usually call these binaries or doubles.
The place Jupiter orbits is not the sun. It's quite near the sun, but it's not the sun.
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The solar system barycenter wanders around, and is outside of the sun only part of the time. IIRC only the combined influence of several planets in alignment gets the barycenter to be outside the sun.
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Mars is quite capable of forcing a tiny fraction of tiny bodies into resonance. That's a far cry from saying "Mars would have cleared its celestial neighborhood of the planetissimals left over after it accreted, in the absence of aid from Jupiter". People have long been abusing the Stern-Levison parameter to say things that it doesn't.
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One problem with calling anything that has reached hydrostatic equilibrium (which really sounds funny, since very few bodies in the Solar System have liquid water) a planet is that there suddenly are hundreds or thousands of them. People want to be able to list the planets easily. Calling Ceres and Ganymede planets goes against traditional usage.
I think a distinction between bodies that have reached equilibrium and bodies that have not would be an excellent one, but I don't think it should be "planet"
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If someone comes up with an actual meaningful need for a different categorization
Even in 2006, over a hundred exoplanets had already been discovered. That is the meaningful need which was already present for a definition that only applied to Solar System objects.
Another reason the prior formula fails is that it includes data dependent on the observer. Suddenly, it matters when you made the observation, which is an absurd thing to do.
I like the proposed definition because it is dependent on relatively easy to determine observables of an exoplanet and its star.
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Making the definition specific to our solar system was on purpose,
So what? My argument is still valid. They could have just kicked the can down the road.
Nonetheless, easy to define proposals don't hurt too much to accept if they can be changed later if the need arises. Of course changing such things seems to create a lot of butthurt on the internet, but that isn't a priority concern among astronomers when defining jargon.
It caused a lot of "butthurt" because the definition was unscientific and unwarranted.
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they said lets make something useful to planetary scientists working in the solar system, and come back again when we need to do something applicable to exoplanets.
So no, they didn't.
No, the vast majority of the butthurt was because Pluto was no longer a planet, and had nothing to do whether it was scientific or not to call Pluto a planet. You could have had the most elegant, scientific definition ever, but if it changed the status of Pluto, the vast majority of the people would be bitching the same, because they didn't even care about the details of the actual definition.
But we didn't have the most elegant, scientific definition ever. We had a kluge passed at the eleventh hour.
Also, it is really annoying to present an irrational argument or decision and then claim, completely without justification, that disagreement would be unabated by actual reason or logic. Why don't you try it first?
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You seem obsessed over something most people don't care about and are able to back it up.
I like you.
Solar System (Score:2)
We should send the IAU out there with some paint to draw a line (circle or ellipse) as to where the edge of the solar system is.
And it's... (Score:2)
...Donald Trump's humility!
Damn that's way out there! (Score:1)
Wow, 3x as far out as Pluto, which is so way way out there it was itself named for the god of the underworld, of death.
And this is 3x further than that! In fact, it is so far out there, I officially name it (pick one):
Trump
Bernie
I'm guessing his parents are ST:TNG fans... (Score:2)
...or maybe it's just required that people named Jean-Luc go into astro/planetary/aerospace lines of work. :-)
You can just spot it in the centre of this image. (Score:1)