Re: Global Energy etc.

[David Bowman <David_Bowman@GEORGETOWNCOLLEGE.EDU>]

Regarding Rick's comment:

> Easier said than done.  The effective area to be blacked out would be 2.6
> million km^2, but you really wouldn't want to shadow any inhabited region
> even for limited periods of time.  I guess you could put up 'filters' that
> block a portion of the sunlight, but they would have to be huge--on the
> order of the area of earth viewed as a circle--130 million km^2.

Rick your calculation and fear of shadows is irrelevant for the
Lagrange point Chuck mentioned.  Your calculation is only for a blocking
shield that is very close to the Earth's surface.  Any solar blocking
shield located at the apropriate Lagrange point that blocked 2% of the
solar radiation would appear as a permanent sunspot on the solar disk of
2% of the angular area of that disk when viewed from Earth.  No place on
Earth would be anywhere near the shield's umbra.  No filter is necessary.

David Bowman
David_Bowman@georgetowncollege.edu