The tilt of our earth

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

  1. timojin Valued Senior Member

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  3. timojin Valued Senior Member

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    Your and Daves explanation are good, but because there are some that there are some change in angle every 40000 years grant you small but there are , or some fluctuation in the Sahara desert must or can be a sign of change in the in the tilt.
     
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  5. river

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    Change in angle every 40,000 yrs. ?

    Interesting where did you get this info ?
     
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  7. timojin Valued Senior Member

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    Some Serbian guy I believe about 18 century with a name Milankovitch?
     
  8. river

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    His theory is what ?
     
  9. sculptor Valued Senior Member

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    Axial tilt, the second of the three Milankovitch Cycles, is the inclination of the Earth's axis in relation to its plane of orbit around the Sun. Oscillations in the degree of Earth's axial tilt occur on a periodicity of 41,000 years from 21.5 to 24.5 degrees.
     
  10. river

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    But what is the essence of these , oscillations ?

    Why do these oscillations occure in the first place ?
     
  11. DaveC426913 Valued Senior Member

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    Fortunately, the universe doesn't need your permission.

    But seriously, you and I both know that you're not really much into the hard sciences.
     
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  12. DaveC426913 Valued Senior Member

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    Because Earth is not a perfect sphere and the Sun and Moon act on it.

    "The precession of the equinoxes is caused by the gravitational forces of the Sun and the Moon, and to a lesser extent other bodies, on the Earth. It was first explained by Sir Isaac Newton.[19]

    Axial precession is similar to the precession of a spinning top. In both cases, the applied force is due to gravity. For a spinning top, this force tends to be almost parallel to the rotation axis. For the Earth, however, the applied forces of the Sun and the Moon are nearly perpendicular to the axis of rotation.

    The Earth is not a perfect sphere but an oblate spheroid, with an equatorial diameter about 43 kilometers larger than its polar diameter. Because of the Earth's axial tilt, during most of the year the half of this bulge that is closest to the Sun is off-center, either to the north or to the south, and the far half is off-center on the opposite side. The gravitational pull on the closer half is stronger, since gravity decreases with distance, so this creates a small torque on the Earth as the Sun pulls harder on one side of the Earth than the other. The axis of this torque is roughly perpendicular to the axis of the Earth's rotation so the axis of rotation precesses. If the Earth were a perfect sphere, there would be no precession."

    https://en.wikipedia.org/wiki/Axial_precession#Cause

    Or don't you "buy that" either?

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  13. river

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    But what you have discribed has not shown why the Earth tilts in the first place .
     
  14. DaveC426913 Valued Senior Member

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    I did that in post 19. Remember?

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  15. river

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    Which I disagreed with
     
  16. DaveC426913 Valued Senior Member

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    No you didn't.

    You simply said you don't believe it. You offered zero input about why you chose not to believe it, or what alternative you might have. Because hard science isn't really your bag.
     
  17. river

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    In my post #30 you gave no evidence on why the Earths tilts in the first place .
     
  18. DaveC426913 Valued Senior Member

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    It was already answered in post 19.
    Would you feel better if I reposted #19 in direct response to your post 30?

    Q:You asked why the Earth tilted in the first place.
    A: We have strong evidence that it was due to a giant impact very early in Earth's history.

    Are you merely being argumentative?
     
  19. river

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    No just trying to understand , without somebody trying to ram a said theory down my throat .
     
  20. DaveC426913 Valued Senior Member

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    There is a fair amount of evidence of an early impact. The Moon itself is probably the largest exemplar.

    But recall, it's more a hypothesis. There are competing hypotheses out there, but this one fits the data best.

    "This sort of formation would explain why the moon is made up predominantly of lighter elements, making it less dense than Earth — the material that formed it came from the crust, while leaving the planet's rocky core untouched. As the material drew together around what was left of Theia's core, it would have centered near Earth's ecliptic plane, the path the sun travels through the sky, which is where the moon orbits today."
    https://www.space.com/19275-moon-formation.html
     
  21. river

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    Theia , hit Earth , dead on .
     
  22. DaveC426913 Valued Senior Member

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    I am not sure why you say that.

    From my post 19:

    " Theia is thought to have struck the Earth at an oblique angle when the Earth was nearly fully formed. Computer simulations of this "late-impact" scenario suggest an impact angle of about 45° and an initial impactor velocity below 4 km/s."
     
  23. river

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