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According to this website, there were 3,372 active satellites in orbit at the beginning of 2021. Furthermore, SpaceX is planning to launch 12,000 satellites to provide cheap internet for everybody, among other functions.

Does this huge collective quantity of objects (together with space trash) reflect away enough solar radiation to have a measurable effect? Could this affect earth's climate, mitigating climate change?

  • I've seen people theorize what it would take to make such satellites create the effect you mention. You'd need an insane amount, basically creating a sunscreen in the process. – Mast Aug 25 '21 at 16:47
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    Obviously the answer is yes, when they're between the earth and the sun. The issue is that they would reflect solar radiation back to Earth when they're behind the Earth but still in sunlight. I'm not sure you could even factor that but the effect must be more than zero – Valorum Aug 25 '21 at 17:16
  • It's not just the sunlight reflected off satellites not in the direct path between the Earth and Sun. You also have the light that is reflected off the Earth, back out into space then off satellites passing overhead and back down to the Earth. I think this pretty much sums up just how ridiculous it would be to come up with an actual % of light either lost or possibly gained. If someone out there has access to some Supercomputer time get on it will you. – diGritz1 Sep 01 '21 at 01:13
  • I am not sure if we should type Earth or earth. –  Sep 02 '21 at 12:19
  • @JeopardyTempest How do you write words as earth and science in the United States? From the info I am searching it should be earth, but not sure. If you wish, edit this. I think it is correctly written as Fred and Farren edited this. –  Sep 02 '21 at 12:21
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    I was just about to message you about your changes. https://grammarist.com/style/earth/ gives a rough rundown that's in line with my thoughts. Capitalize specific names of things. So Earth the place is usually capitalized (it's maybe not 100% absolutely a law, but for me, looks very odd with it lowercase). Whereas, it is earth when we talk about just dirt in general. (Apparently to complicate things it is indeed lowercase when preceded by 'the'... as in "the earth is a sphere"... I guess that's a unique oddity in general, as we don't say The Mars or The JeoaprdyTempest at all. – JeopardyTempest Sep 03 '21 at 09:39
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    Science is fairly similar... it's Science when it's a specific title, like of a subject in school (just like Chemistry, Math, or Cooking). Whereas when we talk about it as a general concept, it should be just lowercase. "This is a science site" ... "It took many years for me to learn the science that I know now." I know English is a complex language, it's not always cut and dry or consistent (and some is probably still evolving... Internet was once always capitalized, but not now). I still struggle to remember it's hablo español and cepíllate los dientes, so at least we struggle both ways! – JeopardyTempest Sep 03 '21 at 09:54
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    I THINK both of these extend the same to British English and the rest of the English speaking world (though can't 110% guarantee it). I usually feel like the variation globally for English is a little less than Spanish, given Spanish changes an entire verb conjugation group and lots of vocabulary cross-Altantic (and even intraHispanic). But English US vs UK has enough little quirks (s vs z, er vs re endings... and even after spending 4 months there in the past 6 years and regularly listening to UK soccer/football, there'll still be words or phrase that surprise me because I've never heard them – JeopardyTempest Sep 03 '21 at 10:05
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    @JeopardyTempest I need a long rest, and it would be nice I publish my first application 1st january. Feel free you or any rep user to edit any of my content. I will be disconnected until then. –  Sep 03 '21 at 13:11
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    @Universal_learner absolutely, this site isn't what really matters, enjoy your rest friend – JeopardyTempest Sep 03 '21 at 19:12
  • @JeopardyTempest Thx friend. I enjoy ESSE. I like to read and it is thanks to this site my english is not even worse. I will be mostly reading, voting, offering bounties if I have more than 1k, and if it comes to me a question I will post it. Also I like to have 1k privileges to edit tags. –  Oct 17 '21 at 12:15
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    @JeopardyTempest The true is I got a bit maniatic past month and I slept badly. I am in a sick leave for a month, and for the moment the doctor says to stay in home. Fine, I am programming the first app. Twitter is nice, but it is hard to have followers and sometimes there is bullying. When I publish my first app I will start to add content, and I will put a link in the app to follow the account. I think after minerals the things that can give me money are list of atoms, list of countries, list of chess openings and list of sport players. –  Oct 17 '21 at 12:15

2 Answers2

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Does this huge collective quantity of objects (together with space trash) reflect away enough solar radiation to have a measurable effect? Could this affect Earth's climate, mitigating climate change?

No.

Suppose, instead of 12,000 tiny satellites, SpaceX was planning on launching 12,000 satellites the size of the International Space Station. The ISS, with its huge solar arrays, has a cross section of about 7,000 square meters (6,528 square meters for the arrays alone). Fun fact: This is about the size of a FIFA-sanctioned international match field. I'll bump up the size to 8250 square meters, the maximum size of a FIFA-sanctioned international match field.

The ISS blocks sunlight that would otherwise hit the Earth about half of the time. I'll halve the 12,000 satellites to 6,000 to reflect this. Six thousand maximum-sized FIFA-sanctioned international match fields results in an area of 49.5 square kilometers. The Earth's cross section to sunlight is $\pi r^2$, where $r$ is the Earth's mean radius (6371 km). This cross section area is $1.275\times10^8$ square kilometers. That's over 2.5 million times larger than those 6000 maximum-sized FIFA-sanctioned international match fields.

Summary: Even 12,000 satellites larger than the ISS would have a minimal impact on the amount of sunlight hitting the Earth. The 12,000 satellites SpaceX is planning to launch are orders of magnitude smaller than the ISS. The impact is in the noise.

Padmanabha
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David Hammen
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  • I found after asking SpaceX is reducing reflection to help astronomers. https://www.bbc.com/news/technology-52391758.amp –  Aug 24 '21 at 14:31
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    @Universal_learner they're doing that so that the satellites don't reflect light into the telescopes and obscure objects in outer space. – Nonny Moose Aug 24 '21 at 19:02
  • Not really asked, but just to add, satellites typically orbit around the equator (although some don't, eg. GPS, Starlink). Thus, it's unlikely the "shading" from satellites would be uniform across the earth. – Ralph Bolton Aug 25 '21 at 08:31
  • @Universal_learner "Musk says" a lot of things.. – smcs Aug 25 '21 at 10:12
  • @smcs Yes, he also say he is going to cure adictions with his program of brain reading, wich I doubt. –  Aug 25 '21 at 10:13
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    @RalphBolton geostationary satellites (less than 600) orbit around the equator. I believe most others (about 1600 active satellites or 7400 "objects in orbit") don't. – jcaron Aug 25 '21 at 16:44
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Yea,but by a mere infinitesimal amount. Earth as a rough sphere has a surface area of 196.9 million square miles or 509 Trillion square meters, add atmospheres thickness 100 miles up it's 200 million of exposed to solar light, 3700 random objects with a area of 5-10 square meters is 37,000 meters square, barely 0.01 square miles, so 1/16 billionth of the Earth's light is blocked by orbiting stuff.

LazyReader
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