I was wondering if anyone has any knowledge about 'libration'. I've been thinking about tidally locked planets a lot lately, and know about the habitable zone [terminator], etc.-- the zone of 'twilight-intense' light in a ring around the planet where life could potentially survive. However, I could only find a few facts about libration-- and it appears to be an oscillating motion.
Do this mean that the habitable zone with oscillate slightly, and both edges of the rings will actually experience day/night cycles, as opposed to my thinking now-- that the habitable zone around the tidally-locked planet is rigid, and there is no day or night cycles?
If this is the case-- there is an oscillation that causes some day/night cycle on the edges of the ring....
How much time would this oscillation be? Would it oscillate and create day/night cycles in the zone of 24 hours [an Earth-day], or would the oscillation occur over more of a 'geologic' time scale-- the light/darkness on the edges of the habitable ring would change over many years?
And if so, how much could this potentially shift the night/light? A few miles? Hundreds of miles?
Thanks!!!