Re: Strange students question...

[Maurice Barnhill <mvb@UDel.Edu>]

crvhs_dks@ncocc.ohio.gov wrote:
>         Greetings everyone.  Today, one of my students had a paper
> that
> had several strange physics questions on it.  Most of them I was able
> to
> figure out, except for a few.  I thought they were rather entertaining
> and made a copy of them.  Can anyone help me with a few of these?
> Here
> they are:
>
> ...
> 2.  Here are four sketches of the moon in a night sky.  Which of these
> positions can and which cannot occur?  (a picture was shown for each)
>         a.  an upper right crescent
>         b.  a lower right crescent
>         c.  an upper left crescent
>         d.  full moon  (this one I know  :-) )

The sun is always on the side of a crescent moon that is away from the
horns.  A crescent moon can't have its horns pointed downward in a night
sky, because that would place the sun above the moon and therefore in
the sky. 

The horns can point left or right of upward depending on whether you are
in the northern or southern hemisphere and whether the moon is in the
western or eastern sky.
-- 
Maurice Barnhill, mvb@udel.edu                
http://www.physics.udel.edu/~barnhill/          
Physics Dept., University of Delaware, Newark, DE 19716