Re[2]: [NatureNS] Moon questions

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From: David <dwebster@glinx.com>
To: naturens@chebucto.ns.ca
Date: Mon, 04 Mar 2019 20:20:57 +0000
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Thanks Both for the explanations. I am a long way from understanding 
this but at least know the relative roles of physics and coincidence.
YT, DW, Kentville

------ Original Message ------
From: "Burkhard Plache" <burkhardplache@gmail.com>
To: naturens@chebucto.ns.ca
Sent: 3/3/2019 9:09:25 PM
Subject: Re: [NatureNS] Moon questions

>Hi David,
>
>the answer to the first question is: Due to 'Tidal Locking'
>(https://en.wikipedia.org/wiki/Tidal_locking),
>which occurs over time between gravitationally  close (astronomically
>speaking) bodies.
>
>The answer to the second question would be 'coincidence at the current time'.
>https://en.wikipedia.org/wiki/Orbit_of_the_Moon#Tidal_evolution
>The gravitational interaction between Earth and Moon causes friction
>(periodic compression
>and decompression of the rocks on both Earth and Moon), which slows
>down the rotation of
>both bodies (causing the above tidal lock).
>This slow down of the bodies' rotations reduces the body internal
>orbital momentum of the Earth-Moon-System.
>The other part of the orbital momentum is the Moon-around-Earth motion.
>Newtonian physics demands that the orbital momentum of a system be conserved.
>When (due to the above mentioned friction) the body-internal component
>decreases,
>the Moon-around-Earth component must increase.
>That increase is achieved by the Moon-to-Earth distance increasing,
>hence the moon slowly moves away from earth.
>
>So, any millions of years ago, the moon appeared larger in the sky,
>and many million years in the future, there would be no more total
>solar eclipses.
>
>Glad we are living today?
>Burkhard
>
>
>
>On Sun, Mar 3, 2019 at 8:37 PM David <dwebster@glinx.com> wrote:
>>
>>  Dear All,
>>      Two things about the moon have puzzled me. Is there some reason why the same side of the moon faces earth ? Does the near side have higher density ?
>>      And two, Is there some physical reason for the moon being just the right size to cover the sun during an eclipse ?
>>      Are both of these just coincidences ? Strange fate indeed.
>>  YT, DW, Kentville

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