From: "Dan Chaffee" 
To: 
Reply-To: "Dan Chaffee" 





Scott,

>And diffraction determines the maximum size of the Airy disc.
>It's up to us to build a scope capable of putting all the light into it.

You can't. The perfect circular aperture can get 84% of the light energy
inside of the disk. The rest does to the rings.

> And since the surface of a planet, etc. is made up of an infinite
>number of point sources of light (all fainter than any star you can see, I
>suspect), isn't it possible that light from each of those points may still
>tend to be at the center of its Airy disc, even though it can still be
found
>anywhere in that disc (or diffraction ring)?

Why do you think this?
Planets are not any darker (in most cases brighter) than the moons that
orbit them, yet the moons are not darker than many stars to us, so a
fragment
of planet that subtends the diameter of the Airy disk would be brighter
than most of the moons.

Dan Chaffee

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