But it is much farther from the sun than announced planets are from theirs.
which leads to:
> But it is much farther from the sun than announced planets are from theirs.
a) So?
b) Is it really? I mean sure, in an absolute sense - but what about in an appropriately scaled sense, allowing for the 1/sixth decreased sun mass and the inverse square force relationships, etc.
c) Even so, see a) - How does this alter the fact that tifally locked doesn't equate to "always presents the same face".
To be clear, I'm just highlighting the fragile and dubious nature of your earlier assertion about tidal locking.
Mercury, lacking ocean or even atmosphere, and mostly frozen solid, is accorded leeway a putatively-habitable planet does not get.
Looking at the moons in our solar system is evidence but not definitive.
Mercury is literally the only body in the whole solar system in any sort of more complicated "lock". So, no, it really is about word games.
How would you even begin to demonstrate this is true? There are so many bodies in the solar system, and we're still fairly frequently discovering new minor planet moon-systems..
The original topic, so cleverly but pointlessly derailed, was the viability of planets we can just barely detect in extremely close orbit around a dim star, in 1:1 tidal lock, with permanently hot and a cold sides, and, likely, no magnetic field. That merited discussion.
> hundreds of moons
> literally the only body
They are all moons, not planets, and not in different star systems. That's not enough to make conclusive statements about exoplanet spin.
That statistic is more relevant to the word games but I'm not here for word games either. It doesn't matter if "lock" implies 1:1.
Agreed, what matters is what percentage of these planets are 1:1 locked.
> All these exoplanets are certainly so locked.
How do you know? Just citing moons in our system isn't enough.
Moons in our solar system orbit closer to planets than planets to the sun, so get locked much more quickly. Venus and even Mercury have not quite got there. Earth is in a more complicated arrangement, which helps us avoid it. That might even have been essential for life.
You may read up elsewhere on what determines the tidal forces, friction, and rotational momentum and energy that determine how long it takes to get into a locked state. That would be smarter than word games.
that doesn't change the argument being made by much. that is still pretty terrible for consistent temperature variations. an extremely long day-night cycle is just about as bad.
For example,
> Mercury .. is tidally locked with the Sun in a 3:2 spin–orbit resonance, meaning that relative to the fixed stars, it rotates on its axis exactly three times for every two revolutions it makes around the Sun.
> As seen from the Sun, in a frame of reference that rotates with the orbital motion, it appears to rotate only once every two Mercurian years.
> An observer on Mercury would therefore see only one day every two Mercurian years.
https://en.wikipedia.org/wiki/Mercury_(planet)