Andrew Nowicki <andrew@nospam.com> wrote in message news:<4092AE0C.8DA11695@nospam.com>...

Rich wrote:
There is one more problem: microwave beams have to be narrow
to provide enough energy density for distant receivers.
Stars and planets are in constant motion, so unless the ET
aims the beam at us for a long time, we will hear only a few
beeps. 

This is not a serious problem.  The distance to the stars, and their
proper motions, are well enough known (or will be soon, within
decades) that there is no problem predicting where they will be when
the signal gets there.  Also it makes sense to make the beam no
smaller than about 10 AU in diameter at the target system (since there
is no guarantee that the telescope is on one of the planets, for
example), so the beam will not fade in and out as a result of the
target planet's motion.  So if we receive it once, and it's
deliberate, it should be easy to receive again.

    Lou Scheffer