Fiction hypothetical about axial rotations

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Discussion Overview

The discussion revolves around a hypothetical scenario involving a fictional planet and its moon, specifically focusing on the concept of axial rotation and tidal locking. Participants explore the possibility of a moon exhibiting an alternating view from the planet, akin to changing lunar phases, rather than a static appearance typical of tidally locked moons.

Discussion Character

  • Exploratory, Conceptual clarification, Debate/contested

Main Points Raised

  • One participant proposes the idea of a moon that alternates its visible sides over cycles, questioning the feasibility of such a gradual change in axial rotation.
  • Another participant mentions that tidal locking typically takes years to establish, suggesting that the writer has some artistic freedom in their narrative.
  • A different viewpoint introduces the concept of 3:2 tidal locking, referencing Mercury's relationship with the Sun, which could provide a model for the fictional scenario.
  • Further discussion acknowledges the example of Mercury but does not resolve whether the proposed alternating view is possible.

Areas of Agreement / Disagreement

Participants do not reach a consensus on the feasibility of the proposed axial rotation and its implications, with multiple competing views presented regarding tidal locking and its variations.

Contextual Notes

Some assumptions about the nature of tidal locking and the time scales involved are not fully explored, and the discussion remains speculative regarding the mechanics of the proposed alternating visibility.

Lapsangtea
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Hello everyone!

I am a fiction writer with a hypothetical question.

For my work I have a new planet, the same size as Earth, with a moon with just a very slightly longer mean orbit (a few days). I have been reading about tidal locking which ensures that observers on the planet only see the nearest side of the moon.

However I am asking whether it is possible to have an axial rotation that appears to 'alternate' with each cycle. For instance, for moon cycle 1 around the planet we would see the near side which would gradually rotate until cycle 2, when we see the far side which would gradually rotate until cycle 3, back to the near, and for cycle 4 we're back to the far, and so on and so forth alternating between each. I'm not talking about turning the satellite around as rapidly as a coin flip, but a kind of gradual change much like the changing lunar phases. I'm also asking about this with respect to the point of view from the planet below (so I know that a tidally-locked moon is actually rotating with respect to the planet, even though it appears 'static'). I think this would mean a kind of wobbly rotation, wouldn't it?

Is this possible and what, if anything, could cause this? I understand it often takes a very, very long time for satellites to 'stabilise'. Perhaps this effect would be impossible to reproduce? Wouldn't it just mean having a faster rotation than being tidally locked??
 
Last edited:
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Hi(gh) Tea, :welcome:

Tidal locking takes a few years so set, so you have a bit of artistic freedom there :smile:
 
How about 3:2 tidal locking, like Mercury? Opposite side to Sun on each orbit.
 
BvU said:
Hi(gh) Tea

Ahahaha!
Thank you for pointing out the Mercury example as well.
 

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