Setting Sun

Date: 19 May 1995 15:28:07 -0400
From: Anonymous
Subject: Setting sun

Dear Swat Team:

A fellow Naval retiree and I have been discussing whether the
sun appears to set faster at the horizon near the equator
than it does in the Northern latitudes.

My assumption is that it is the same, but I can't
come up with an arithmetic explanation.

So, does it or does it not appear to set at the same
rate and if so, why??

Many thanks,

Rich Messina
RICHM8595@aol.com
FAX (914) 246-0691

Date: 20 May 1995 10:05:54 -0400
From: Dr. Ken
Subject: Re: Setting sun

Hello there!

Well, actually the sun does set somewhat quicker in the lower latitudes.
Strange but true!  Here's why.  In the Northern latitudes (such as in
Minnesota, where I'm from) the sun never really gets very high overhead.  It
just always traces out an arc in the Southern sky.  If you look at the path
that the sun has traced out in the sky, you'll notice in the high latitudes
that the path makes a fairly low angle with the horizon at sunset; it kind
of skids along the horizon for a while before it really sets for good.  So
from the time that a little piece of the sun first dips below the horizon to
the time that the whole sun is below the horizon, you've got a long,
drawn-out sunset.  This effect is more extreme the farther North you go,
culminating in sunsets that last the entire day near the North Pole.

By contrast, near the equator (anywhere between the two tropics, really) the
sun makes a head-first dive for the horizon every day, and so the time that
the sun spends partially obscured is pretty short.  Hope this helps you out!

-K