-----------------------------------------------------------------------------------------------------------------------

This is something of a side issue but, way back when, I remember that *everyone*, & every book I read, believed that Mercury was tidally locked.
Then, some years later, it was proven that Mercury was not, in fact, tidally locked.
I've never read nor heard an explanation.
Could it be that it's "on it's way" but just hasn't gotten 'there' yet?

--------------------------------------------
On Fri, 8/26/16, C. Berry <xxxxxx@gmail.com> wrote:

 Subject: Re: [TML] Earth 2?
 To: xxxxxx@simplelists.com
 Date: Friday, August 26, 2016, 9:42 AM

 Gravity
 drops with the square of distance, but tidal effects drop as
 the cube. So a world that close to its star is going to
 "feel" proportionately much greater tidal effects
 than Earth does.
 Tidal
 braking doesn't work by distorting the body into a
 single shape. Rather, the sub- and anti-primary points
 deform upward, and those 90 degrees away inward, in response
 to tidal forces. But then that sub-primary bulge rotates
 "ahead" of the sub-primary point, and because it
 takes time to settle back, you end up with a persistent
 asymmetry. The primary pulls "backward" on this
 asymmetric bulge, which applies torque that slows down the
 body's rotation. Eventually, the body locks into a
 single orientation, with a now-permanent bulge axis aimed
 through the primary. This is what happened to Luna, and
 indeed to all the large moons in the solar
 system.
 On Fri,
 Aug 26, 2016 at 9:36 AM, Christopher Sean Hilton <xxxxxx@vindaloo.com>
 wrote:
 On Fri, Aug 26, 2016 at 09:09:11AM
 -0700, C. Berry wrote:

 >    Odds are very good that this planet is tidally
 locked. So climate zones

 >    would work very differently from how they do on a
 rotating planet.

 >    You'd need a thick atmosphere to provide
 enough heat circulation to

 >    keep all the air from freezing out on the
 permanent night side. On

 >    Proxima b, I'd expect the nicest temperatures
 and any extensive liquid

 >    water to be in the center of the day side.

 >

 Can someone elaborate on why the odds are good that
 this planet is tidally

 locked? Assume I understand a little about how tidal locking
 works[1]. I'm asking

 because if most singleton planets are tidally locked to
 their

 primaries then would you not have better chances of finding
 an

 earth-like experience on a gas giant moon?

 [1] I assume the mechanism behind tidal locking is that
 under

 gravitational stress, the world stops being a sphere and
 becomes more

 of an ovoid. Over millions of years, gravity on the lobes of
 the ovoid

 exerts a torque which slows or speeds up the rotation of the
 world

 until it matches the period with which it orbits it's
 primary.

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