Re: [Phys-l] celestial motion

["John Clement" <clement@hal-pc.org>]

One could argue that sunsets happen where you are located, so the sunset
happens in the valley before the mountain top.  The published sunset is of
course referenced to an imaginary horizon which may only be visible on the
great plains or the ocean.  I don't know if the published sunset takes into
account the visible size of the sun.  I suspect it just is when the center
of the sun has gone down, and not when the last sliver disappears.  I also
doubt it takes into account refraction.

What is the scientific or astronomical definition of sunset, if there is
one?  Is there an ISO standard on this?  What would the physics police say?

John M. Clement
Houston, TX

> On 08/22/2008 07:24 AM, Anthony Lapinski wrote:
> >  When we look at a sunset, it already
> > happened. Since light takes about 8 min to go from the Sun to Earth,
>
> Sunsets don't "happen" at the sun.
>
> Sunsets happen at the horizon, which is (with rare exceptions) only a
> few miles away from wherever you are.
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