Talk:Space sunshade

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This article was nominated for deletion in the past. The result of the discussion was keep.

Contents 1 Old talk 2 insulation vs. insolation 3 Ridiculous 4 Definition 5 Re Writing 6 Title 7 Sun-Earth L1 Distances 8 Number of Sunshades required for 2% reduction

[edit] Old talk

For the archived deletion debate for this article see Talk:Sunshade/delete -- Graham ☺ | Talk 22:17, 17 Jul 2004 (UTC)

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How about calling it a solar shade? (c.o. Alpha Centauri, the computer game). It sounds a bit more spacy, and less like a parasol or sunglasses.Bibble 20:08, 12 Jul 2004 (UTC)

[edit] insulation vs. insolation

While Venus's atmosphere probably is a better insulator than earth's, isn't the more relevant fact that Venus receives more insolation (incoming solar radiation) than earth? I did not change the page myself because I thought I might have misunderstood the writer's point.

[edit] Ridiculous

This sunshade idea is ridiculous. It will not reduce CO2 because sun light is not the problem. Vegetation reduce CO2 when it receive light. Less light means less CO2 absorbtion by vegetation. If you want to reduce CO2, plant trees and let them have as much light as possible, not the opposite!!!

Ah, come on. "As much light as possible" doesn't work since too much light kills off the plants and evaporates the water they need to survive. Besides, the additional heat perturbs the weather pattern (witness the 2007 monsoon season – ouch!) which kills off even more plants.
NB: Please sign your discussion contributions. Thanks. — smurfix 17:40, 9 August 2007 (UTC)

[edit] Definition

Shouldn't the article start with a definition ("A sunshade is ...")? HistoryBA 00:46, 16 November 2005 (UTC)

[edit] Re Writing

I have re writen most of the article, making more clear what it is and what it does, I have also provided some more information about how it works, as well as a picture.

[edit] Title

The present title is rather confusing since most folks would regard a sunshade as being another name for a parasol. I suggest moving the page to Space sunshade as being more descriptive. Bridgeplayer 15:51, 13 May 2007 (UTC)

I'd agree with that - to me, a sunshade is something you put inside the car windscreen to stop it getting too hot. Although it would mean creating a disambig from the town, I think there ought to be a redirect from Soletta as well, given that that's the name Kim Stanley Robinson uses, which is where I suspect most people would have come across the concept — iridescent (talk to me!) 19:27, 13 May 2007 (UTC)

[edit] Sun-Earth L1 Distances

The distances from earth used in this article appear to be incorrect. They place the objects inside the orbit of the moon. The Sun-Earth L1 is about 150,000,000 km according to the Lagrangian_point article. This is my first post to a discussion section, so I hope I got it right. Jason3777 16:35, 19 May 2007 (UTC)

Extremely good point - the 24000km in the article is below geostationary orbit let alone the L1 point. Angel's original paper talks about having it at 1.5 Gm (1.5 million km), don't know where the error crept in. Have corrected it — iridescent (talk to me!) 16:59, 19 May 2007 (UTC)

[edit] Number of Sunshades required for 2% reduction

The article states that “In theory it would have a diameter of 210 kilometers.” This diameter represents an area of 34,636 sq km. The earth has a radius of 6,378.140 km [Peterson Field Guide₢ - Stars and Planets p. 534, ISBN 0-395-93431-1] which represents a planar area of 127,802,093 sq km. Even at L1 where I believe the radius required to eclipse the entire earth completely would be 6,316 km, this small of a radius (105 km) would require a lot of Sunshades to reduce the light from the sun by 2%, as shown in the picture. I think the text needs to be updated to make clear that there would need to be many Sunshades of 210 km diameter to produce the 2% reduction in the sun’s light hitting the earth. Jason3777 21:55, 19 May 2007 (UTC)

In fact the area to totally eclipse the Earth gets larger, not smaller, the closer you get to the sun -- since, surprise, the sun is somewhat larger. However, you certainly are correct — the radius should be more like 900km for 2% coverage, which is still a whole damn lot of mirrors. smurfix 17:37, 9 August 2007 (UTC)

Roger Angel's research paper mentions 100,000 km radius, which is - um - a slight difference. I'll guess the 210km figure is left over from the old Kim Stanley Robinson-style geostationary shade proposal — iridescent (talk to me!) 22:32, 19 May 2007 (UTC)