Assuming that rotation of stars, galaxies etc is determined basically randomly, the question is: why do all space objects rotate so 'neatly', with little or no precession? And what precession there is seems to be caused just by different kinds of friction I guess.

I would imagine that a condensing gas cloud that forms a star has all kinds of random angular momentum inside it and that the resulting star would have some complex rotation, with the axis of rotation precessing all over the place. What is wrong with this picture?

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    $\begingroup$ Counter-question: what is a "natural" amount of precession? Why does a toy top precess over a few dozen rotations, while Earth's axis processes over millions of days (26 kyr)? What are the interactions which determine these timescales? $\endgroup$
    – rob
    Feb 24, 2021 at 15:06
  • $\begingroup$ @rob My point is that we know from observations that "natural" amount of precession is small : speeds are slow and angles are small. Why don't we see objects that precess with big angles like 90 degrees, for instance? $\endgroup$ Feb 24, 2021 at 15:40
  • $\begingroup$ Wouldn't you describe the motion of pulsars as "presessing"? $\endgroup$ Feb 24, 2021 at 15:43
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    $\begingroup$ From wikipedia: "When an object is not perfectly solid, internal vortices will tend to damp torque-free precession, and the rotation axis will align itself with one of the inertia axes of the body." I'd like to know more about this, so upvote to the question. $\endgroup$
    – tom10
    Feb 24, 2021 at 15:47
  • $\begingroup$ @ScienceGeyser Perhaps? But pulsars are those weird high energy things, I don't know nearly enough about them and anyway they seem like a special case to me. $\endgroup$ Feb 24, 2021 at 16:31


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