I think it would be possible to deploy a thin mesh in outer space that could cast a light shadow on a particular spot on the earth. The shadow would obviously be slightly larger than the mesh since it is closer to the sun (but not much). If the mesh was covered by thin lightweight wafers they angle of the wafers could vary the light let through the mesh. In addition, the backside of the wafers could be reflective and allow sunlight to be directed to a different spot on the earth's surface.

Wait a minute... a 007 movie is coming back to me...
-- MoreCowbell, Jun 06 2006

Space umbrellas to fight global warming http://news.bbc.co..../nature/4762720.stm
Article also nicely explains why this is not a good idea. [django, Jun 06 2006]

//The shadow would obviously be slightly larger than the mesh since it is closer to the sun // No, it would be smaller, at least the area of pure shadow would be. (Look up solar eclipses and read about umbra and penumbra.) But that's pedantry, which some of us are good at.

Some of us are also very picky about originality, and about giving at least half of an idea about how to make something work. For instance, how is this mesh to stay up? If it's in orbit, it won't stay over one spot.

Welcome to the Halfbakery.
-- baconbrain, Jun 06 2006


no geosynchronous orbit? I think I've seen this before using mylar, but I'm not sure.
-- Zimmy, Jun 06 2006


Space umbrellas and sunshades to fight global warming have already been proposed. [see link]. It's called geo- and cosmo-engineering.

Welcome to the HB.
-- django, Jun 06 2006


You don't want geosycronos orbit as that is always straight up from one spot.

What you want is to put the parasol between the one spot on earth that you want to shade and the sun. So the parasol would have to be near the L1 point, but it would have to move at a variable rate of speed relative to both the L1 point and the earth. Basically it will have to be powered.
-- Galbinus_Caeli, Jun 07 2006


This sounds like Simpsons episode where Mr. Burns wants to block out the sun in order to force people to use electricity.
-- phundug, Jun 07 2006


That's not gonna keep much rain off from up there above the clouds...
-- ye_river_xiv, Jul 26 2006



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