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posted by takyon on Tuesday January 22 2019, @08:47AM   Printer-friendly
from the planet-doubt dept.

The strange orbits of some objects in the farthest reaches of our solar system, hypothesised by some astronomers to be shaped by an unknown ninth planet, can instead be explained by the combined gravitational force of small objects orbiting the Sun beyond Neptune, say researchers.

The alternative explanation to the so-called 'Planet Nine' hypothesis, put forward by researchers at the University of Cambridge and the American University of Beirut, proposes a disc made up of small icy bodies with a combined mass as much as ten times that of Earth. When combined with a simplified model of the solar system, the gravitational forces of the hypothesised disc can account for the unusual orbital architecture exhibited by some objects at the outer reaches of the solar system.

[...] "The Planet Nine hypothesis is a fascinating one, but if the hypothesised ninth planet exists, it has so far avoided detection," said co-author Antranik Sefilian, a PhD student in Cambridge's Department of Applied Mathematics and Theoretical Physics. "We wanted to see whether there could be another, less dramatic and perhaps more natural, cause for the unusual orbits we see in some TNOs. We thought, rather than allowing for a ninth planet, and then worry about its formation and unusual orbit, why not simply account for the gravity of small objects constituting a disc beyond the orbit of Neptune and see what it does for us?"

[...] Earlier attempts to estimate the total mass of objects beyond Neptune have only added up to around one-tenth the mass of Earth. However, in order for the TNOs to have the observed orbits and for there to be no Planet Nine, the model put forward by Sefilian and Touma requires the combined mass of the Kuiper Belt to be between a few to ten times the mass of Earth. [...] "It's also possible that both things could be true -- there could be a massive disc and a ninth planet. With the discovery of each new TNO, we gather more evidence that might help explain their behaviour."

Shepherding in a Self-Gravitating Disk of Trans-Neptunian Objects

Related: CU Boulder Researchers Say Collective Gravity, Not Planet Nine, Explains Orbits of Detached Objects


Original Submission

Related Stories

CU Boulder Researchers Say Collective Gravity, Not Planet Nine, Explains Orbits of Detached Objects 16 comments

Collective gravity, not Planet Nine, may explain the orbits of 'detached objects'

Bumper car-like interactions at the edges of our solar system—and not a mysterious ninth planet—may explain the the dynamics of strange bodies called "detached objects," according to a new study. CU Boulder Assistant Professor Ann-Marie Madigan and a team of researchers have offered up a new theory for the existence of planetary oddities like Sedna—an icy minor planet that circles the sun at a distance of nearly 8 billion miles. Scientists have struggled to explain why Sedna and a handful of other bodies at that distance look separated from the rest of the solar system. [...] The researchers presented their findings today at a press briefing at the 232nd meeting of the American Astronomical Society, which runs from June 3-7 in Denver, Colorado.

[...] [Jacob] Fleisig had calculated that the orbits of icy objects beyond Neptune circle the sun like the hands of a clock. Some of those orbits, such as those belonging to asteroids, move like the minute hand, or relatively fast and in tandem. Others, the orbits of bigger objects like Sedna, move more slowly. They're the hour hand. Eventually, those hands meet. "You see a pileup of the orbits of smaller objects to one side of the sun," said Fleisig, who is the lead author of the new research. "These orbits crash into the bigger body, and what happens is those interactions will change its orbit from an oval shape to a more circular shape." In other words, Sedna's orbit goes from normal to detached, entirely because of those small-scale interactions.

Also at Popular Mechanics, where Planet Nine proposer Konstantin Batygin disputes the findings:

Batygin, of Caltech, tells Popular Mechanics that any sufficiently strong gravitational encounter could detach an object from Neptune's embrace, but for the distant small bodies of the Kuiper belt to have done so through "self-gravity"—as the CU model proposes—there would need to be about five to ten times the mass of Earth in the outer parts of the Kuiper belt. There isn't.

"Unfortunately, the self-gravity story suffers from the following complications," Batygin says. "Both observational and theoretical estimates place the total mass of the Kuiper belt at a value significantly smaller than that of the Earth [only 1 to 10 percent Earth's mass]. As a consequence, Kuiper belt objects generally behave like test-particles enslaved by Neptune's gravitational pull, rather than a self-interacting group of planetoids."

Planet Nine.

Related: Planet Nine's Existence Disfavoured by New Data
Medieval Records Could Point the Way to Planet Nine
Another Trans-Neptunian Object With a High Orbital Inclination Points to Planet Nine
Outer Solar System Origins Survey Discovers Over 800 Trans-Neptunian Objects
LSST Could be the Key to Finding New Planets in Our Solar System


Original Submission

The Search for Planet Nine Continues; Potential Candidate Found 35 comments

Where *Isn't* Planet 9? Search for Planet Nine still continues

Not long ago astronomers Mike Brown and Konstantin Batygin (the two original people proposing the existence of the planet) used the alignments of the TNO orbits to back-calculate the potential location of the unseen planet in space. It's a kind of treasure map to find the planet.

In a new paper they've put that map to use, looking through survey data in a hunt for Planet 9.

[...] Brown and Batygin wrote software that simulates where Planet 9 would be and how bright it would appears for various values of its size, reflectivity, and orbital shape. They created a database of positions and brightnesses for it, and then combed through the [Zwicky Transient Facility (ZTF)] database to look for it, going through the past three or so years of observations since the facility started its survey campaign.

[...] They ran 100,000 simulations of various parameters for the planet, and looked to see if the ZTF would've seen it if it were indeed smaller and closer to us. They determined that it would've been seen in the survey about 56,000 times out of the 100,000, so just looking at that their non-detection indicates the chance it's smaller and closer is now less than 50%, making it more likely it's farther out, bigger, and fainter.

The larger Vera C. Rubin Observatory is expected to find many previously hidden objects in the solar system, and is scheduled to begin full operations in October 2023. It will accumulate all-sky survey data around 10 times faster than the Zwicky Transient Facility.

Also at ExtremeTech.

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  • (Score: 0, Redundant) by Anonymous Coward on Tuesday January 22 2019, @08:48AM (2 children)

    by Anonymous Coward on Tuesday January 22 2019, @08:48AM (#789996)

    Pluto!!!!

    • (Score: 2) by Pax on Tuesday January 22 2019, @11:24AM

      by Pax (5056) on Tuesday January 22 2019, @11:24AM (#790027)

      "PLUTO"
      ok pal WTF has that Disney bastard dog got to do with this.. i mean really.. when Mickey and Minnie were getting divorced the judge was asked Mickey "sorry Mt Mouse you cannot divorce your wife for having prominent front teeth.. she's a mouse for goodness sake!"...
      And Mickey said " no Your Honour.. I said she was fucking goofy!"

    • (Score: 0) by Anonymous Coward on Wednesday January 23 2019, @11:46PM

      by Anonymous Coward on Wednesday January 23 2019, @11:46PM (#790925)
      Eris is more massive than Pluto. So does it get to be Planet Ten? Makemake and Haumea aren't that far behind, so do they get to be Planets Eleven and Twelve? So too with Quaoar and the long known asteroid Ceres (which would renumber all the planets if we go by distance from the sun, and just as much if we go by discovery date, as it was discovered before Neptune). There could potentially be a lot of other more obscure objects out there awaiting discovery which are in Pluto's size range. The point is there is no consistent definition of a planet that would include Pluto but at the same time reject many other similar, lesser-known solar system objects. Call Pluto a planet if you like, but astronomers will continue using the definition of planet that is most useful to them, and that definition excludes Pluto and other similar bodies.
  • (Score: -1, Offtopic) by Anonymous Coward on Tuesday January 22 2019, @01:37PM

    by Anonymous Coward on Tuesday January 22 2019, @01:37PM (#790065)

    The author of the GPL licensed text-mode casino game "GPC-Slots 2" has rescinded the license from the "Geek feminist" collective.
    ( https://lkml.org/lkml/2019/1/17/52 [lkml.org] )
    ( https://slashdot.org/submission/9087542/author-recinds-gpl [slashdot.org] )

    [Notice: the revocation of the "Geek Feminists"'s license /just/ occurred. 2019. January.]

    The original author, after years of silence, notes that the "Geek Feminist" changed[1] a bunch of if-then statements which were preceded by a loop waiting for string input to a switch statement. The author reportedly noted that to use a switch statement in such an instance is no more preformant than the if-thens. Switch statements should be used where the input to the switch statement is numerical, and of a successive nature, for most efficient use of the jump table that is generated from said code.

    The author reportedly was offended, after quiet observation of the group, that the "Geek Feminists" mocked his code, mocked his existence as a male, and never did any work on the code afterwards and never updated to include new slot machines added to the original code by author subsequently.

    The author notes that he neither sought nor received any compensation for the granted license, that is was a gratuitous license, and that there never was any refutation of his default right to rescind given. (A right founded in the property law of licenses.)

    The copyright owner has reportedly watched quietly as each year the "Geek Feminists" published a recount of their heroic efforts regarding his code.[2][3] Presumably he has now had enough of it all...

    The author notes that the SF Conservancy attempts to construe a particular clause in the GPL version 2 license text as a "no revocation by grantor clause", however that clause states that if a licensee suffers and automatic-revocation by operation of the license, that licensees down stream from him do not suffer the same fate. The author of "GPC-Slots 2" reportedly notes that said clause does only what it claims to do: clarifies that a downstream licensee, through no fault of his own, is not penalized by the automatic revocation suffered by a licensee he gained a "sub-license" from (for lack of a better term.)

    The author reportedly notes that version 3 of the GPL did not exist when he published the code, additionally the author notes that even if there was a clause not to revoke, he was paid no consideration for such a forbearance of a legal right of his and thus said clause is not operative against him, the grantor, should it exist at all.

    (Editor's note: GPL version 3 contains an explicit "no-revocation-by-grantor" clause, in addition to a term-of-years that the license is granted for. Both absent in version 2 of the GPL)

    The author reportedly has mulled an option to register his copyright and then to seek damages from the "Geek Feminists" if they choose to violate his copyright post-hence.

    (Editors note: Statutory damages for willful copyright infringement can amount to $150,000 plus attorney's fees for post registration violations of a differing nature to pre-registration violations.)

    [1]https://geekfeminism.org/2009/10/19/
    [2]https://geekfeminism.org
    [3]http://geekfeminism.wikia.com

    GPC-Slots 2 is a text console mode casino game available for linux with various slot machines, table games, and stock market tokens for the player to test his luck. For the unlucky there is a Russian Roulette function.

    [Notice: the revocation of the "Geek Feminists"'s license /just/ occurred. 2019. January.]

    Addendum: Statements from the program author:

    "It's my right to rescind the permission I extended.
    I have done so.

    You speak as if me controlling my property is a criminal act.
    And to you people, perhaps it is.

    If the "geek feminists" wanted a secured interest, they would have to pay for one."

    "I did rescind the license, yesterday"

    >Reportedly
    "I did rescind the license, yesterday

    Not "reportedly" anymore."

    "
    >Then you should have used them.
    Not necessary, the language used in the press release identifies them easily.

    >should
    As if I somehow can't just rescind using their names either.

    License to use/modify/etc the GPC Slots 2 code is hereby terminated for. Alex "Skud" Bayley, and Leigh Honeywell.
    (Note: this termination is not to be construed as a lifting of the previously issued termination regarding the "Geek Feminism collective", this termination is an addendum)
    "

    "
    You will just keep saying that I cannot rescind permission to use my property.
    And you are wrong.

    I can and _I HAVE_ (from the previously identified people). I have that power as the owner of the work. It is not YOUR work, it is not THE WORLD's property (I did _not_ dedicate it to the public domain), it is M I N E.

    I know this very well. I am studied in the law. I know the bullshit defenses non-owners try to pull against owners (mostly equity "pleees not fair judge" - usually when they don't like an increase in payments)

    There is no K, I am not bound by the terms that I require people using my property to follow. If they do not follow the terms they are simply violating MY copyright and I sue for damages. If I decide I don't want them to use my property I can revoke permission at any time, then if they continue to use it: again they are violating MY copyright and I sue them for damages.
    "

    ------------------------------------------------------------
    >p46 "As long as the project continues to honor the terms of the licenses under which it recieved contributions, the licenses continue in effect. There is one important caveat: Even a perpetual license can be revoked. See the discussion of bare licenses and contracts in Chapter 4"
    --Lawrence Rosen

    >p56 "A third problem with bare licenses is that they may be revocable by the licensor. Specifically, /a license not coupled with an interest may be revoked./ The term /interest/ in this context usually means the payment of some royalty or license fee, but there are other more complicated ways to satisfy the interest requirement. For example, a licensee can demonstrate that he or she has paid some consideration-a contract law term not found in copyright or patent law-in order to avoid revocation. Or a licensee may claim that he or she relied on the software licensed under an open source license and now is dependent upon that software, but this contract law concept, called promissory estoppel, is both difficult to prove and unreliable in court tests. (The concepts of /consideration/ and /promissory estoppel/ are explained more fully in the next section.) Unless the courts allow us to apply these contract law principles to a license, we are faced with a bare license that is revocable.
    --Lawrence Rosen

    >p278 "Notice that in a copyright dispute over a bare license, the plaintiff will almost certainly be the copyright owner. If a licensee were foolish enough to sue to enforce the terms and conditions of the license, the licensor can simply revoke the bare license, thus ending the dispute. Remeber that a bare license in the absence of an interest is revocable."
    --Lawrence Rosen

    Lawrence Rosen - Open Source Licensing - Sofware Freedom and Intellectual property Law

    >p65 "Of all the licenses descibed in this book, only the GPL makes the explicity point that it wants nothing of /acceptance/ of /consideration/:
    >...
    >The GPL authors intend that it not be treated as a contract. I will say much more about this license and these two provisions in Chapter 6. For now, I simply point out that the GPL licensors are in essentially the same situation as other open source licensors who cannot prove offer, acceptance, or consideration. There is no contract."
    --Lawrence Rosen

    ----
    >David McGowan, Professor of Law, University of Minnesota Law School:

    >"Termination of rights

    >[...] The most plausible assumption is that a developer who releases code under the GPL may terminate GPL rights, probably at will.

    >[...] My point is not that termination is a great risk, it is that it is not recognized as a risk even though it is probably relevant to commercial end-users, accustomed to having contractual rights they can enforce themselves.

    Discussions with author of program involved:
    http://8ch.net/tech/res/1013409.html [8ch.net]
    http://8ch.net/tech/res/1017824.html [8ch.net]
    http://8ch.net/tech/res/1018729.html [8ch.net]

  • (Score: 3, Funny) by Thexalon on Tuesday January 22 2019, @02:42PM (1 child)

    by Thexalon (636) Subscriber Badge on Tuesday January 22 2019, @02:42PM (#790077)

    Figuring that gravity is coming from objects we know about, such as the Kuiper Belt, rather than a really large object that somehow has been able to hide while we've found much smaller objects.

    I'm not saying there's no Planet 9 From Outer Space, but those who think it exists would be a lot more convincing if they actually found it.

    --
    The only thing that stops a bad guy with a compiler is a good guy with a compiler.
    • (Score: 2) by bob_super on Tuesday January 22 2019, @05:14PM

      by bob_super (1357) on Tuesday January 22 2019, @05:14PM (#790143)

      That would not be the first time we found a planet after noticing its influence on other things. It just gets harder the farther we go.

      Last time I checked my gravity equations, a bunch of distributed mass versus a single massive object was equivalent. But if we're talking about a disc centered around the sun, then the center of mass wouldn't be where a planet would be. That disc has to be pretty darn clumpy.

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