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How quickly could precession happen?


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The Earth's axis precesses every 26000 years. Would it be possible for a planet's axis to precess with a period of one year? Is there any reason why that could not happen?

The question is inspired by watching game of thrones which appears to have two seasons going on. The seasons that we would recognise and a "long winter". That lead to a geekish conversation about orbital mechanics suggesting that a planet with a more elliptical orbit and a fast precession could create such a pattern of seasons. (discussions about dragons we left to the biologists).

 

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16 hours ago, jnb said:

The Earth's axis precesses every 26000 years. Would it be possible for a planet's axis to precess with a period of one year? Is there any reason why that could not happen?

 

 

I would imagine that for a planet to have a very short precessionary period it would need to be very oblate (fat around the middle) , have a good sized moon nearby in just the right orbit and also be very close to the star. Such a planet, even if it was astrophysically feasible would be 1000's of  degrees C  and unlikely to have any meaningful sort of atmosphere.

What do you mean by 'period of one year': one Earth year or the time it takes for said planet to orbit its star?

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By a period of one year we were thinking of one earth year. The rationale being that with a precession lasting in the order of one earth year that would provide seasonal variation over that time scale with the precession tilting the axis with respect to its star. A second period could be introduced by having a large elliptical orbit. So for example a planet with an elliptical 30 year orbit around a red giant could have a 15 year winter while at aphelion.

Why would it need to be close to the star?

 

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