Hi. I've been a lurker here for a while as I contemplate building my own projector but I was thinking about a non PJ idea of mine and suddenly thought maybe the folks here with all their expert knowledge of focal lengths and light frequencies might have some answers. Math just isn't my strength...

I am going to try and keep this short for the first post (if there is interest I will post some diagrams etc). I got this idea during a solar eclipse ... With all the talk of global warming the idea occured to me instead of trying to change the air how about changing the sun? More to the point, how about installing an orbital array of flat mylar "lenses" to reduce the sun's energy before it hits the atmosphere. Put into the most basic of terms: give the Earth a set of sunglasses.

For purposes of discussing the math let us assume that the danged thing could actually be built.

QUESTION 1:
Assuming such an array casts a conical shadow how far between the sun and the earth would it need to be to cause a full planetwide shading and how large (or more correctly how small) could it be made in order to accomplish that task?

Known variables that probably matter:

Earth Diameter: 12,760 km
Sol Diameter: 1,400,000 km
Distance from Earth to Sol: 190,000,000 km

QUESTION 2:
What do you think of this "mad science" idea ?

i like the heating up, i hate cold winters. so not for me
it's also way to superexpensive

First there is almost no man caused warming of the earth. The sun has made a little extra heat lately.

If you placed a few million square feet of reflective material between the earth and sun and even blocked less than .001% of the sun all of mankind would soon die! Even a slight cooling of the earth will make for world wide drought. The warming fools have no idea what keeps mankind alive ---- water. Amost all of it is from the ocean and this is because of evaporation from the sun and wind. Any large reduction of sunlight over time could cause less evaporation and less rain everywhere.

AZ and CA would have millions of people with no water. I could go on.

Please let the sun and the earth find it's own temp and stop listening to the crazy teachers.

400 reasons not to believe in GW.

http://epw.senate.gov/public/index.cfm?Fus...teReport#report

Hi, it appears that Mars is undergoing global warming so this might also point to the theory that it is a natural occurance. On the other hand, if New York City and Florda start to go under the sea we might see science kick in for some active solutions. (I like energy independence from oil and carbon sequestration.) When I think of man made solutions though, I like to think about the effect of just one volcano. It exploded sometime in the 1800s and it created the year without a summer. If I remember my history, it snowed in June in London.

If mankind, or what we evolves to lives for a 1000 years more, WE mankind will be able to see if there anything this global warming thing at all, -or if it is just a normal reacuring peak/spike over a periode of time.

WE NEED MORE RECORDED DATA, lets think CHEAP and BETTER ENERGY until we got enough data.
-let try to minimize what we use, DONT drive 12cyllinder Bigblock cars (although i would like one, if i had the money to pay the fuel).
Use the elements of our planet, and harvest there "unlimitless" energy WIND WATER FIRE.
-I know that not the american way, but it works, OK to drive a 4cylinder 1,3liters 95hp car.

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My answer: Forget about "global warming" and do it for yourself, tell Greenpeace and the Sierra Club to go take a hike (pun intended) and start controlling your own destiny. Don't be a slave to OPEC, the banks or utility companies any longer. My solution is here.