At 12:14 -0800 03/20/2002, bhakti wrote:
>actually, you can't really treat the sun like a point. it's about half a
>degree wide, and that effects shadows.
Not to mention that fifty-mile-thick diffusion layer we've got
wrapped around the planet. Atmosphere does a lot to fuzzify, scatter
and otherwise diffuse the light. If it did not the sky would not be
its characteristic hue.
But even in a vacuum the Sun is not, strictly speaking, a point source, true.
Buzz Kettles wrote:
> & next you'll be suggesting that the sun doesn't actually move
>across the sky?
Actually it doesn't. I'm sure you realize that though.
Wellllllllll... I suppose it depends how you define motion.
If you define motion as being relative to other items in the sky
(such as the background of stars), the sun actually does appear to
move a little as Earth revolves around it.
If you define motion as being relative to the horizon, yes the sun moves.
If you define motion as meaning "the sun revolves about the Earth",
technically that is not totally inaccurate, since Earth and the sun
actually orbit a common gravitational point. That point is so close
to the sun's core that there's no obvious effect, of course. But the
sun is not, technically speaking, a completely immobile anchor point
about which the solar system swings. (Earth and the Moon do the same
kind of dance, causing the planet to wobble a bit on its axis. Hence
the tides.)
And of course the entire solar system is merrily rolling along the
galaxy, which is itself moving through the universe.
--
Warren Ockrassa | http://www.nightwares.com/
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