Lunar Libration Explained: The Science Behind the Moon's Wobble

[@star_titan]

Nicely explained 👌👌

[@AstroPhil2000]

@@star_titan Thank you!

[@Alien_Planetology]

I'm still baffled by how a tidally-locked object can have an obliquity relative to its orbit. By my (apparently limited) understanding, it seems like the process of tidal locking would set the object's rotational axis perpendicular to its orbital plane. Wouldn't the rotation of a tilted object try to carry its tidal bulge up (or down) and away from alignment with the parent and induce a torque?

[@AstroPhil2000]

Yes it does in cause a torque and long term you end up with changes to the orbit, like it becomes more circular. Or inclination evolves. Interestingly, if the object has a fluid centre and solid crust, or fluid middle and soild core and crust, the libration can be a sign of a hidden ocean. The solid material and liquid respond at different rates to tides, causing a delay in the rotation. This too can cause it to "rock" back and forth.

[@Alien_Planetology]

@@AstroPhil2000 Oh wow! That's really interesting. Thanks!