Changing moon/earth distance.

When the astronomers at McDonald Observatory measure the exact distance
between the moon and earth with their lasers, do they do it at the
exact same time of the year (down to the same minute)?? Since this
distance is always changing (apogee/perigee). This would be a crucial
factor in determining the exact distance.

Don Hamilton

Dear dlham:

wrote:
When the astronomers at McDonald Observatory measure
the exact distance between the moon and earth with their
lasers, do they do it at the exact same time of the year
(down to the same minute)?? Since this distance is always
changing (apogee/perigee). This would be a crucial
factor in determining the exact distance.

So you are asking if they are idiots, with no knowledge of orbital
mechanics or any history on what was known about the Moon's orbit prior
to 1960 or so?

Google on
"lunar laser ranging"

You will get hits like:
http://www.csr.utexas.edu/mlrs/dda.html

David A. Smith

wrote in message oups.com...
When the astronomers at McDonald Observatory measure the exact distance
between the moon and earth with their lasers, do they do it at the
exact same time of the year (down to the same minute)?? Since this
distance is always changing (apogee/perigee). This would be a crucial
factor in determining the exact distance.

Don Hamilton

LOL! Yes, of course they do!

http://antwrp.gsfc.nasa.gov/apod/ap051113.html

On 19 Jan 2007 08:43:09 -0800, wrote:

When the astronomers at McDonald Observatory measure the exact distance
between the moon and earth with their lasers, do they do it at the
exact same time of the year (down to the same minute)?? Since this
distance is always changing (apogee/perigee). This would be a crucial
factor in determining the exact distance.

No. It wouldn't be critical to do it at the same time of year because
the distance earth-moon is never the same at the same time of year.
It is important to know the exact time of the observation and it is
important to make a continuous series of observations.

Bud
--
The night is just the shadow of the Earth.