Hi Clyde,
Interesting idea! Also one with lots of problems. I last remember hearing something of this sort proposed as a temporary solution to global warming. You probably could do it, given enough resources, but here are some of the downsides:
1) It’s expensive
2) It’d have to be awfully big (planet-sized) The global-warming solution may only need to occlude out a small part of the sun’s disk for any given spot on the planet. I’m not sure if that’s good enough for this application, though.
3) I’m pretty sure there’s not a stable orbit of anything between the Earth and the Sun with the right period and which always stays in line. There’s a Lagrange point between the Earth and the sun, but the orbit’s unstable. You’d have to constantly adjust its position with thrusters. The stable Lagrange points are in the orbit path of the Earth and won’t work for this application.
4) Not everyone on the planet may appreciate their sunshine blotted out (for example, farmers, beach resorts far away from the poles, and owners of solar power arrays).
Tom
5) Reducing photosynthesis, even away from farms, is not a great idea either. Mike W.
(published on 10/22/2007)