A poster in sci.astro asked why the moon appears larger on the horizon than at the zenith.

A poster in sci.astro asked why the moon appears larger on the horizon
than at the zenith. The following responses appeared:

(excerpts, revised)

From: brad@looking.UUCP (Brad Templeton)
Date: 16 Aug 87
Subject: The real truth about the moon
Newsgroups: sci.astro

Actually the moon appears so much larger because it is almost
twice as close to you when on the horizon as it is when it is
overhead.

When the moon is on the horizon, it is attracted by all the mass
of the Earth you see running from where you are standing to the
point on the horizon where you see the moon. Up above you,
there is no mass of Earth between you and the moon, so the force
is less.

The massive force brings the moon much closer when it rises and
sets. As it gets higher, the force is less, and it moves
further away. Then it comes back in again.

The moon is actually closest to the Earth when below the
horizon, only you can't see it then. Those of us on the other
side of the Earth actually get a really good view. Apollo
reached the moon by leaving from the other side of the Earth
when the moon was close.
_________

From: al@gtx.com (0732)
Date: 20 Aug 87
Subject: Re: The real truth about the moon
Newsgroups: sci.astro,talk.bizarre

Of course, no one who lacks even a cursory knowledge of
elementary physics can doubt that the above explanations have
merit, but the primary effect is a physiological one. As one
tilts his head back to observe the moon at the zenith, the lens
of the eye is flattened by gravity and its magnifying power is
decreased.