(SNES) Earth as a 10,000- Mile Aperture Objective Lens

["Pilotstar" <pilotstar@mindspring.com>]

Our atmosphere should act as a gigantic lens approximately 10,000 miles in
diameter with a  focal length of about 458,00 miles (f/46). (Talk about
aperture fever!) Of course, the Earth itself would be an 8,000 mile central
obstruction, but this still leaves PLENTY of clear aperture. The cloudy and
most turbulent atmospheric conditions are in our troposphere, which extends
only up to about seven miles above the earth's surface. A space probe with
adaptive optics in earth orbit at the earth's atmosphere's focal length
could provide some truly spectacular views! For example, extra solar planets
might be easily seen directly by using the Earth's body as an "occulting
disk."

I realize I'm over-simplifying the situation in this brief posting, as the
Earth's atmosphere is not perfectly spherical (that would introduce
spherical aberration anyway), varies in size and shape with solar activity,
would have chromatic aberration, etc.; but I'm surprised no space probe
equipped with the proper aberration correcting and adaptive optics has been
used to test this concept as an aside to its primary mission.


I tried to use the FDO Website's Utility Tools on refraction and amount of
atmosphere above/below a given altitude to firm up the feasibility of such a
concept, but couldn't make its answers gel; is the atmosphere above/below
function working properly? Appreciate any feedback on using our atmosphere
as a lens.

Ernie
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