Stories
Slash Boxes
Comments

SoylentNews is people

posted by cmn32480 on Saturday October 22 2016, @04:23PM   Printer-friendly
from the weebles-wobble-but-they-don't-fall-down dept.

Arthur T Knackerbracket has found the following story:

The massive hypothetical object, which supposedly looms at the edge of our solar system, has been invoked to explain the strange clustering of objects in the Kuiper belt and the unusual way they orbit the Sun.

Now Planet Nine predictors Konstantin Batygin and Mike Brown of Caltech, along with graduate student Elizabeth Bailey, offer another piece of evidence for the elusive sphere's existence: It adds "wobble" to the solar system, they say, tilting it in relation to the sun.

"Because Planet Nine is so massive and has an orbit tilted compared to the other planets, the solar system has no choice but to slowly twist out of alignment," lead author Bailey said in a statement.

Before we go any further, a caveat about Planet Nine: It's purely theoretical at this point. Batygin and Brown predict its existence based on unusual perturbations of the solar system that aren't otherwise easily explained. (This is the same technique scientists used to find Neptune.) But the history of astronomy is rife with speculation that is never borne out: The same guy who correctly predicted the existence of Neptune also believed that a planet he called Vulcan was responsible for the wobble of Mercury. That "discovery" caused the astronomy world to waste years looking for something that wasn't there. (Mercury's wobble was eventually explained by the theory of general relativity.)

But the evidence offered by Batygin and Brown is compelling. When the pair announced their find in January, planetary scientist Alessandro Morbidelli of the Côte d'Azur Observatory in Nice, France, told The Washington Post: "I don't see any alternative explanation to that offered by Batygin and Brown."

"We will find it one day," he added. "The question is when."

Planet Nine's angular momentum is having an outsized impact on the solar system based on its location and size. A planet's angular momentum equals the mass of an object multiplied by its distance from the sun, and corresponds with the force that the planet exerts on the overall system's spin. Because the other planets in the solar system all exist along a flat plane, their angular momentum works to keep the whole disk spinning smoothly.

Planet Nine's unusual orbit, however, adds a multi-billion-year wobble to that system. Mathematically, given the hypothesized size and distance of Planet Nine, a six-degree tilt fits perfectly, Brown says.


Original Submission #1; Original Submission #2

 
This discussion has been archived. No new comments can be posted.
Display Options Threshold/Breakthrough Mark All as Read Mark All as Unread
The Fine Print: The following comments are owned by whoever posted them. We are not responsible for them in any way.
  • (Score: 2) by WalksOnDirt on Sunday October 23 2016, @05:52AM

    by WalksOnDirt (5854) on Sunday October 23 2016, @05:52AM (#417766) Journal

    Two objects orbiting each other cannot be stable[1]. The rotational energy can cause their mutual orbit to contract or expand (like the Earth, Moon system), and gravitational radiation will act to contract their orbit.

    It doesn't seem to be known whether the Earth and Moon would separate until they move into different orbits or, after they reach some maximal separation, shrink their orbits until they end up in collision; except that we know that the Sun will go red giant before then.

    [1]If they are the only objects in the Universe there might be an exception.

    Starting Score:    1  point
    Karma-Bonus Modifier   +1  

    Total Score:   2  
  • (Score: 2) by HiThere on Sunday October 23 2016, @06:23PM

    by HiThere (866) Subscriber Badge on Sunday October 23 2016, @06:23PM (#417907) Journal

    A reasonable argument, given a long enough period of time, but it ignores that they can both be tidally locked. (Improbable, but so is the pair being in isolation long enough for tidal effects to break the orbit...unless one is quite massive, and the other reasonably close. Even binary star systems have been observed being broken up by external effects.

    That said, a three body system makes things a lot more complex, and small effects can cascade...given ENOUGH time. But in orbital mechanics enough is usually either quite a brief period, or quite a long period. The intermediate cases seem to be comparatively rare.

    Then again, if you wait long enough the protons may evaporate....well, ok, that's an unproven theory, and if they do it's REALLY slowly, but nothing seems to be really permanent. So if we want to call anything a stable orbit, then most planet/moon systems, or even asteroid/moon systems seem to qualify. They are more likely to be disrupted by external events than by orbital decay.

    --
    Javascript is what you use to allow unknown third parties to run software you have no idea about on your computer.
    • (Score: 2) by WalksOnDirt on Sunday October 23 2016, @11:17PM

      by WalksOnDirt (5854) on Sunday October 23 2016, @11:17PM (#417985) Journal

      ...but it ignores that they can both be tidally locked

      That wasn't ignored. In that case they radiate gravitational waves until they collide. What was ignored was friction with any gas in the space, but that entails (at least) a third object, which I implicitly assumed would not matter. For smaller objects than stars it is likely to be more important than gravity waves.

      • (Score: 2) by HiThere on Monday October 24 2016, @05:30AM

        by HiThere (866) Subscriber Badge on Monday October 24 2016, @05:30AM (#418048) Journal

        ...but it ignores that they can both be tidally locked

        That wasn't ignored. In that case they radiate gravitational waves until they collide. What was ignored was friction with any gas in the space, but that entails (at least) a third object, which I implicitly assumed would not matter. For smaller objects than stars it is likely to be more important than gravity waves.

        Are you sure about that? I thought that after they both became tidally locked they stopped emitting gravity waves. Of course, if only one of them were tidally locked, the system would keep emitting gravity waves, and that's the more common occurrence. The easiest way to get it to happen such that they were both tidally locked would seem to be a comet/asteroid with two pieces held together by some ice having the ice sublime as it warmed up. ... and that already brings in a third body.

        --
        Javascript is what you use to allow unknown third parties to run software you have no idea about on your computer.
        • (Score: 3, Informative) by WalksOnDirt on Monday October 24 2016, @06:28AM

          by WalksOnDirt (5854) on Monday October 24 2016, @06:28AM (#418054) Journal

          Any[2] two objects orbiting each other will emit gravity waves. Their rotation has nothing to do with it. For anything of stellar mass or less it will take an unreasonably long time, though.

          If two objects are not tidally locked their orbits will expand or shrink until they are tidally locked or, if there is enough energy available in their rotation, they collide or escape each other. This has nothing to do with gravity waves, and is caused by tides.

          Mutually tidally locked objects are easy to produce. Pluto and Charon form one such pair.

          [2]Electrons don't really orbit nuclei.