http://www.worldwidetelescope.org/wwtweb/thumbnail.aspx?name=SolarSystem{$DATE}Tidal Lockinghttp://www.worldwidetelescope.org/wwtweb/thumbnail.aspx?name=SolarSystemThe Moon's rotation is
synchronous with its
orbit around the Earth.http://www.worldwidetelescope.org/wwtweb/thumbnail.aspx?name=SolarSystemThis means we always
see the same "face" of
the Moon as it orbits.http://www.worldwidetelescope.org/wwtweb/thumbnail.aspx?name=SolarSystemThis is called 'synchonous
rotation' or 'tidal locking'.
This occurred due to the
differential gravitational force
of the Earth on the Moon.http://www.worldwidetelescope.org/wwtweb/thumbnail.aspx?name=SolarSystemAt this rate in 100 billions years
the Earth will also be tidally locked
to the Moon.
But this is beyond the lifetime of our Sun...http://www.worldwidetelescope.org/wwtweb/thumbnail.aspx?name=SolarSystemMecury is almost tidally
locked with the sun.http://www.worldwidetelescope.org/wwtweb/thumbnail.aspx?name=SolarSystemIn Mercury's case it is because
of the diffential gravitation
force from the Sun.http://www.worldwidetelescope.org/wwtweb/thumbnail.aspx?name=SolarSystemThis means that one Mercury day
is longer than one Mercury year!PNG
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