The tilt of our earth

Discussion in 'General Science & Technology' started by timojin, Nov 24, 2017.

  1. Seattle Valued Senior Member

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    No, that would be you.
     
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  3. river

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    Irrelevant

    To your last statement , anyone who knows me knows that I'm not anti-science . Just not in mainstream science thinking restrictions .
     
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  5. Seattle Valued Senior Member

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    2,573
    What is "non-mainstream science without restrictions". Would that be anything that comes into your head? If so, how is that "science" mainstream or not?
     
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  7. paddoboy Valued Senior Member

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    This forum knows you and I believe would agree with my summation of you as evidenced by your many trolling posts, anti science comments that defy physics and observations, and your obvious delusions in believing you are some sort of deeeeeeeeeeep thinker while the rest of us languish as has beens.
     
  8. river

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    Restrictions such as Cosmic Plasma , cosmology .
     
  9. paddoboy Valued Senior Member

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    21,647
    Another example of your dishonesty in attempting to justify your anti science rants.
     
  10. Seattle Valued Senior Member

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    2,573
    Cosmology is the study of how the universe formed. How is that a "restriction". Biology is the study of living things. Is that a "restriction" too?
     
  11. iceaura Valued Senior Member

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    24,469
    Having several possible explanations to choose from, and large amounts of evidence to use in arguments for competing explanations, is not the same as having no clue.
     
    Last edited: Nov 26, 2017
    exchemist likes this.
  12. river

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    It is actually .

    The guessing continues .
     
  13. Seattle Valued Senior Member

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    2,573
    What is your particular interest in the tilt of the Earth and of all the other planets?
     
  14. DaveC426913 Valued Senior Member

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    It is a proposed alternate hypothesis. And it has some problems.
    Don't get ahead of yourself.
     
  15. DaveC426913 Valued Senior Member

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    Don't make such stupid statements.

    Your anti-science flag is flying.
     
    Last edited: Nov 26, 2017
    exchemist likes this.
  16. timojin Valued Senior Member

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    Wiki
    Milankovitch cycles describe the collective effects of changes in the Earth's movements on its climate over thousands of years. The term is named after Serbian geophysicist and astronomer Milutin Milanković. In the 1920s, he theorized that variations in eccentricity, axial tilt, and precession of the Earth's orbit resulted in cyclical variation in the solar radiation reaching the Earth, and that this orbital forcing strongly influenced climatic patterns on Earth.

    Similar astronomical theories had been advanced in the 19th century by Joseph Adhemar, James Croll and others, but verification was difficult because there was no reliably dated evidence, and because it was unclear which periods were important.

    Now, materials on Earth that have been unchanged for millennia are being studied to indicate the history of Earth's climate. Though they are consistent with the Milankovitch hypothesis, there are still several observations that the hypothesis does not explain.
     
  17. paddoboy Valued Senior Member

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    No it isn't....and again, you don't fool anyone river with your continued avoiding questions.
     
  18. paddoboy Valued Senior Member

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    Nothing other then the usual anti science rant, or excuse to slip in his debunked Plasma/Electric universe hypothetical, while proclaiming long and loud the existence of the paranormal, supernatural, Aliens, giants and just about anything that science has debunked.
     
  19. timojin Valued Senior Member

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    Be specific otherwise you are just a a nice nice guy .
     
  20. paddoboy Valued Senior Member

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    I was specific with his usual debunked Plasma/Electric hypothetical.
    And yes, I am certainly a nice guy, in fact my Mrs insists a real nice nice guy.

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  21. paddoboy Valued Senior Member

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    https://arxiv.org/pdf/1607.08630.pdf
    28 Jul 2016

    Outer-planet scattering can gently tilt an inner planetary system:

    ABSTRACT

    Chaotic dynamics are expected during and after planet formation, and a leading mechanism to explain large eccentricities of gas giant exoplanets is planet-planet gravitational scattering. The same scattering has been invoked to explain misalignments of planetary orbital planes with respect to their host star’s spin. However, an observational puzzle is presented by Kepler- 56, which has two inner planets (b and c) that are nearly coplanar with each other, yet are more than 45 degrees inclined to their star’s equator. Thus the spin-orbit misalignment might be primordial. Instead, we further develop the hypothesis in the discovery paper, that planets on wider orbits generated misalignment through scattering, and as a result gently torqued the inner planets away from the equator plane of the star. We integrated the equations of motion for Kepler-56 b and c along with an unstable outer system initialized with either two or three Jupiter-mass planets. We address here whether the violent scattering that generates large mutual inclinations can leave the inner system intact, tilting it gently. In almost all of the cases initially with two outer planets, either the inner planets remain nearly coplanar with each other in the star’s equator plane, or they are scattered violently to high mutual inclination and high spin-orbit misalignment. On the contrary, of the systems with three unstable outer planets, a spin-orbit misalignment large enough to explain the observations is generated 28% of the time for coplanar inner planets, which is consistent with the observed frequency of this phenomenon reported so far. We conclude that multiple-planet scattering in the outer parts of the system may account for this new population of coplanar planets hosted by oblique stars.

    CONCLUSION
    We have run simulations attempting to implement the idea of Huber et al. (2013) for tilting the inner planets via scattering of outer planets, and found it to be unlikely in the case of two-planet scattering but plausible in the case of three-planet scattering. We ran 173 simulations of two outer-planets, of which only one produced high enough spin-orbit misalignment of the inner two planets to match the observations. However, for this outcome, the planet’s mutual inclination is about 20◦ for most of its evolution, too high for a reasonable match with Kepler-56 b and c’s mutual inclination (Huber et al. 2013). We did not find another system with similarly high inclinations, even though we did find a few systems where one of the inner planets ended up with a high inclination. We speculate that the system S3 had its second-outermost planet ejected and the highest inner-planet inclinations came from the same source – an epoch of prolonged scattering which allowed access to these dynamically rarer outcomes. However, considering our simulations, our hypothesis of the outer planet(s) generating a high spin-orbit misalignment requires particularly violent scattering. This is apparently possible through 3 equal-mass outer planets, but not with 2. In runs with three planets in the exterior parts, scattering can tilt the inner system dramatically. For inner systems that are not disrupted, 28% showed misalignment from the original plane of the outermost planet by more than 45◦ at a randomly selected time in the future secular evolution of the system. Our runs showed that usually two outer planets remain after the scattering, whereas in Kepler-56, only one has been found. New data and analysis appears to confirm the existence of a third planet in the Kepler-56 system (Otor, Montet et al., in prep.). It does not exclude the existence of a fourth planet in a large orbit, which could still be hiding. Observationally, a fourth planet has currently an 95% upper limit on a long term radial velocity acceleration of 3.2 m/s/yr (Otor, Montet et al., in prep), which is why we quoted results with respect to this benchmark above. The second outer planet in our simulations almost always had a much smaller effect – it could easily evade that limit. A useful avenue for future work would be quantifying whether 3 unequal-mass planets can achieve large enough misalignments. Also, our focus was on one particular system (Kepler-56), but one would rather model a population of systems, whose initial distribution is plausible from planet formation theories, to see what distribution of spin-orbit and mutual inclination outcomes are expected for the inner planets. Misalignment of inner planets is likely not rare. Kepler-56 was the 6th system of multiple transiting planets whose stellar obliquity was measured (Albrecht et al. 2013) – the search turned up an oblique star unexpectedly quickly. Indeed, another system, KOI- 89, has recently been found to feature large angle spin-orbit misalignment of its two inner, coplanar planets (Ahlers et al. 2015). In contrast to Kepler-56, there is no known additional object orbiting further out. Nevertheless, it is common enough that if scattering indeed explains this population, then we would suggest multi-planet scattering is more common than two-planet scattering. There are observational clues that scattering is probably not the sole mechanism generating misalignments. Mazeh et al. (2015) have found stellar misalignment to be a strong function of stellar temperature, but not of planetary multiplicity or coplanar architecture. A third planet does not appear to be needed to produce systems with similar characteristics as Kepler-56, thus weakening scattering as a major mechanism for spin-orbit misalignments of two or more coplanar planets. A host of other mechanisms may also be in play. The protoplanetary disk may have been tilted from its inception (Tremaine 1991; Bate et al. 2010; Fielding et al. 2015), or due to magnetic torques in its early stages (Lai et al. 2011). It could have endured a torque from a previously-bound stellar companion (Batygin 2012) or from a flying-by star (Xiang-Gruess 2016). Even more exotic, the internal convection might have even tilted the stellar surface (Rogers et al. 2013) relative to the planetary plane. Most of these mechanisms would likely leave the non-transiting planet in roughly the same plane as the transiting planets. Such a configuration will eventually be testable, as orbital precession of the inner planets due to the outer one will become observable in transit data due to the slow but steady duration drifts, the manifestation of planetary precession (Miralda-Escude 2002). ´ Our main conclusion is that three outer-planets are necessary for scattering to cause the amount of misalignment inferred for Kepler- 56’s planets b and c. Two-planet scattering does not seem suffi- cient, because the excitation is rarely dramatic enough. Apparently in these cases, scattering in part of the planetary system propagates chaos to all other parts as well. This conclusion is probably much more general than our attempts to model the Kepler-56 system. In particular, it has been the upshot of attempts to model the early days of the Solar System (Brasser et al. 2009; Agnor & Lin 2012; Kaib & Chambers 2016). This conclusion may more broadly apply to exoplanets as well. For instance, since many or most planetary systems of small planets exhibit dynamically packed and rather calm orbits (Fabrycky et al. 2014), and most systems of giant planets have large eccentricity (Cumming 2010), it may suggest that these two types of systems are truly separate, expressing two distinct outcomes of the planet formation process.
     
  22. iceaura Valued Senior Member

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    This appears to be orbital tilting, not rotational axis tilting (of the planets themselves, anyway).
     
  23. Janus58 Valued Senior Member

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    But a change of inclination of the orbit will result in a change in the obliquity.
    The top image shows a planet with an obliquity of 0 (axis of rotation at a right angle to the orbital plane).
    The bottom shows the same planet after the inclination of its orbit has been changed, Since the direction the axis of rotation doesn't change, the angle between the rotational axis and the orbital plane does, and we get a different obliquity.

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