[time-nuts] Latitude and longitude question

Hal Murray hmurray at suespammers.org
Mon Jul 10 19:04:21 EDT 2006


> I just read an article about measuring gravitational waves in the
> latest   IEEE about the effects of tides and the moon gravitation on
> the earth-crust -   that the earth crust moves up and down about 30cm
> every day, plus the   gravitational effects cause about 300ps shift
> day to day. 

Friends in the radio astronomy business (VLBI) told me about the tide problem 
several years ago.  They need to know where their antennas are so they can 
compute what the signal looks like.  Their database of antenna positions also 
includes velocity.  :)

The other place where I heard about (solid) earth tides was a paper from 
CERN.  They weren't getting as good an answer as then expected.  Finally, 
they corrected for the phase of the moon (really tides) and their data looked 
much better.  Their experiment was very very sensitive to the diameter of the 
ring.  It gets slightly bigger when the earth expands due to the tide.  That 
was many years ago.  Probably more than 10.


The article from Physics Today March 2006, Time Too Good to Be True
  http://www.physicstoday.org/vol-59/iss-3/p10.html
discusses gravitational blue shift, but I don't remember any numbers.



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