NavList:

   

Reply

Earlier today, referring to the displacement of the Moon's position caused
by parallax, I said-

>It's always a vector
>pointing toward the zenith, and the closer the Moon passes the zenith, the
>faster the direction of that vector will change. And it's the effect of
>that rapidly-changing vector, resolved along the Moon's path, that causes
>the effect of parallax on the lunar distance to be changing most quickly as
>the Moon passes meridian.

Well, that was wrong, in that parallax always pushes the apparent position
of the Moon down, away from the zenith, so the vector representing that
displacement should point away from the zenith, not toward the zenith. It
doesn't affect the subsequent argument, or its conclusion, at all.

Sorry about that.

George.

================================================================
contact George Huxtable by email at george@huxtable.u-net.com, by phone at
01865 820222 (from outside UK, +44 1865 820222), or by mail at 1 Sandy
Lane, Southmoor, Abingdon, Oxon OX13 5HX, UK.
================================================================

   

Reply