Who needs street lights? Chinese city plans fake moon
In Chengdu, there is reportedly an ambitious plan afoot for replacing the city's street lights: boosting the glow of the real moon with that of a more powerful fake one.
The capital of the southwestern Chinese province of Sichuan plans to launch an illumination satellite in 2020. According to an article in People's Daily, the artificial moon is "designed to complement the moon at night", though it would be eight times as bright. The "dusk-like glow" of the satellite would be able to light an area with a diameter of between 10 and 80km (six to 50 miles), while the precise illumination range could be controlled within tens of metres – enabling it to replace street lights.
The vision was shared by Wu Chunfeng, the chairman of the private space contractor Chengdu Aerospace Science and Technology Microelectronics System Research Institute Co (Casc), at a national mass innovation and entrepreneurship event held in Chengdu last week. Wu reportedly said testing had begun on the satellite years ago and the technology had now evolved enough to allow for launch in 2020. It is not clear whether the plan has the backing of the city of Chengdu or the Chinese government, though Casc is the main contractor for the Chinese space programme.
Also at The Guardian and Inverse.
(Score: 0) by Anonymous Coward on Friday October 19 2018, @01:34AM (4 children)
How many of these fake moons would it take to reflect the same amount of light back as all the CO2?
(Score: 0) by Anonymous Coward on Friday October 19 2018, @07:01AM (3 children)
I'll take the lack of response to mean "less than one".
(Score: 2) by Nuke on Friday October 19 2018, @08:32AM (2 children)
.... or infinity.
(Score: 3, Funny) by Runaway1956 on Friday October 19 2018, @03:18PM (1 child)
Isn't the question akin to asking how many oranges does it take to bake an apple pie?
(Score: 0) by Anonymous Coward on Friday October 19 2018, @03:32PM
It should just be a matter of counting photons.
(Score: 2) by sjames on Friday October 19 2018, @01:40AM (1 child)
It sounds like the ultimate magnifying glass and ant hill situation.
(Score: 2) by Phoenix666 on Friday October 19 2018, @01:56PM
Yeah, I always thought it would be fun to put a fresnel lens in orbit.
Washington DC delenda est.
(Score: 5, Informative) by Runaway1956 on Friday October 19 2018, @01:42AM (5 children)
All of nature observes a circadian rhythm. Not just man, but all of nature. How is that night glow going to affect agriculture, and wild animals, and even the fish? And people.
If a mob of hormonal women tear these people limb from limb within the next year, we'll know that they didn't really think it through.
(Score: 1, Funny) by Anonymous Coward on Friday October 19 2018, @04:42AM
They really should have thought of that before they built the concrete cities :)
(Score: 2) by Kell on Friday October 19 2018, @06:05AM (3 children)
Admittedly, we were hormonal before the Perma-Moon.
Scientists ask questions. Engineers solve problems.
(Score: 2) by aiwarrior on Friday October 19 2018, @07:37AM (2 children)
I honestly do not understand why there are not night lights which are motion sensitive.
I really really do not understand. Is it their sensitivity? I guess with the amount of energy you save you would buy a fricking radar for lamp posts.
Everybody would be happy:
People would feel safe, even more because they know anything will trip the light to turn on.
We could see a night sky
We would save on money
We would help our energy footprint.
(Score: 4, Interesting) by Unixnut on Friday October 19 2018, @09:27AM (1 child)
(a) In my experience they are jarring. My eyes adjust to the night, then a light randomly comes on when I get near it, surprising me, and ruining my night vision, then it turns off when I carry on, rendering me with night blindness until my eyes adjust a few mins later, only for the cycle to repeat next time I approach such a light.
(b) People tend to want to illuminate at a distance. This is why torches are used at night, they throw the light far ahead, so you can see at a distance. Having a light turn on just above you is of limited use. You want the path ahead of you lit as far as possible. Most of the motion sensitive lights I know only turn on within a couple of meters of you.
(c) They are complex and error prone. All kinds of things can set them off at random points, things like leaves rustling, or wild animals, or birds. The opposite is also true, where the motion sensors stop working, and there is no light at all. They are more expensive then standard one and require higher maintenance.
If you want to see the night sky, save on money and help reduce energy, do what they do round my area. You have cheap standard streetlights, and you turn them all off from 1am till 6am, completely. Anyone who is out at that time will use a torch, even on their phone if needs be. Cars (what few there are, maybe one every 2 hours) have headlights since forever, so they are not a problem, and on a clear night, with the full moon, you can see by moonlight. It is also cheap, because the complete investment doesn't involve ripping out all the streetlamps and fitting motion sensor enabled ones. Instead your total investment is a master switch in the local distribution box with a 24h timer.
Plus, as all the other villages and towns in the region turn off the lights at the same time, you get phenomenal night skies, you can really see so much of the universe, it is mindblowing (especially for me, who originally grew up in a dense urban area).
(Score: 1, Interesting) by Anonymous Coward on Friday October 19 2018, @11:23AM
a) This really depends on the density of the light pole field. But the variation is a killer, it takes like 30 minutes or so to perfectly accommodate for a healthy person! So you might be fairly blind all the time if the lights are badly placed.
b) This is a good point but we could monitor not just movement but also speed and direction and illuminate accordingly. Does make things again a little more complex.
c) KISS is always a great idea. And it's a shame we cannot see the wonderful night sky in cities. And already more than half of humanity lives in cities so they might never have seen the majestic star field above us.
Yet another question is if you have street lights, why do they have to be so eye-piercingly bright. It's a street, not a hospital operations room..!
I believe this Chinese grand scheme is in the same vein as the Transit Elevated Bus. [wikipedia.org]
(Score: 2, Insightful) by optotronic on Friday October 19 2018, @01:48AM (8 children)
Clouds?
(Score: 3, Funny) by c0lo on Friday October 19 2018, @01:55AM
Simple: CDN!
https://www.youtube.com/watch?v=aoFiw2jMy-0 https://soylentnews.org/~MichaelDavidCrawford
(Score: 2) by Runaway1956 on Friday October 19 2018, @02:01AM (2 children)
Even on a cloudy night, the thing should work reasonably well. The moonshine is evident on cloudy nights, most of the time. Daylight hours are only interrupted by the severest of stormy weather, after all. At a guess, five nights out of the year, this new super-streetlight will be worthless. Another fifteen or twenty nights, it will only do some good. Most cloudy nights, it's still going to shine, just not as well as on cloudless nights. So, you get roughly eight times the light that you would get from a full moon, except, it shines reliably, every night, except really really bad stormy nights. On these nights, even criminals and cops are taking shelter from the storm, so who is going to notice?
I'll have to give it a thumbs up. It should serve the purpose intended.
(Score: 0) by Anonymous Coward on Friday October 19 2018, @02:58PM (1 child)
I guess you don't know clouds?
Thanks for your "opinion", but only works in clear skies. Anyway, I'll leave this here about the past.
https://www.smithsonianmag.com/smart-news/how-russian-space-mirror-briefly-lit-night-180957894/ [smithsonianmag.com]
(Score: 2) by Runaway1956 on Friday October 19 2018, @03:17PM
No, dude. I've never seen clouds. And I've never seen clouds at night. Never in all my life. /sarcasm
As I stated, pretty clearly, on most overcast nights, you still get some light on the ground, when the moon is full. On very stormy and overcast nights, you'll get none, or none that a human can see. On less stormy nights, you'll get more light. If there's just a little overcast - "partly cloudy" - that big nightlight in the sky works pretty well.
They're talking about a light that is 8 times brighter than the full moon here. So, it's 8 times more likely that light will penetrate whatever overcast there might be.
Full fledged tornado breeding storms won't be penetrated, at all. Normal thunderstorms will probably be brightened up a little bit, but not much. Normal, everyday overcast should be lightened up appreciably.
(Score: 0) by Anonymous Coward on Friday October 19 2018, @02:22AM (1 child)
What about seeing the stars? Are there any observatories in the area that might as well be moved if all this light pollution is permanent?
And what about hopeless romantics, out for a walk on a crisp winter evening--romance is just not going to work if you can't see some stars. I predict lower birth rates for the rural areas surrounding that city (maybe this is a good thing?)
(Score: 2, Funny) by Sulla on Friday October 19 2018, @05:24AM
Romance? Joyful walks? Talk about a lower birth rate?
Please report next Tuesday to your local magistrate for assignment to a reeducation camp.
Ceterum censeo Sinae esse delendam
(Score: 0) by Anonymous Coward on Friday October 19 2018, @02:50PM (1 child)
On a cloudy day you just shine lights up at the clouds, and it will reflect down.
My first year near a big city it was unnerving for me to see how bright it actually was at night on a cloudy day. I had a fenced in back yard and it was usually very dark back there, but on a cloudy night I could walk around without any need or desire for a flashlight.
(Score: 2) by toddestan on Friday October 19 2018, @10:32PM
Agreed. While some of the light could shine through clouds, it will be dominated by city lights reflected back down by the clouds.
If you really want to see nighttime lit up, come up north some night when it's snowing. Between the clouds and the fresh coat of white snow covering everything in the city, you can very easily read a newspaper outside.
(Score: 5, Interesting) by MostCynical on Friday October 19 2018, @02:20AM (1 child)
Don't they know these things could be weapons [schlockmercenary.com]?
Further disussion here [aleph.se]
"I guess once you start doubting, there's no end to it." -Batou, Ghost in the Shell: Stand Alone Complex
(Score: 3, Interesting) by realDonaldTrump on Saturday October 20 2018, @09:06AM
We'll be ready for it. Space Force!!
(Score: 0) by Anonymous Coward on Friday October 19 2018, @05:20AM (6 children)
This smells like complete bullshit. Such a satellite would have to be unbelievably enormous, like building another moon, or perhaps another sun.
Like, the full moon is about 30 arcminutes across when viewed from earth. Something like 10% of all the solar energy striking the full moon is reflected back towards the Earth. The moon is pretty big, about 3500km in diameter. This means it gets a lot of energy from the sun. How is this satellite going to be powered? By the sun? Even if you make this thing 5km in diameter (in LEO that'll look about the same size as the moon when viewed from from Earth) you'd be getting about a millionth of the solar energy that the moon does.
(Score: 5, Informative) by maxwell demon on Friday October 19 2018, @05:55AM (5 children)
It has to be enormous, but not that enormous.
First, the moon is black. Really. Black as coal. To be more concrete, the moon has an albedo of 0.12. Which means that is reflects less than 1/8 of the light. Since a mirror reflects close to 100% of the light, this compensates the factor 8 in brightness planned.
Second, the moon is a diffuse reflector. The mirror reflects directed. Even if we assume the mirror to be perfectly flat (I guess they will actually make it a concentrating mirror), that gives a factor 2.
Third, they speak of 3 mirrors; if they all reflect into the same area, this gives another factor of 3.
But the most important point is that the satellite is much closer than the moon. The moon has a distance of about 380 000 km. This satellite will probably have to be geostationary, giving a distance of 36 000 km (if not geostationary, it will be even closer). This gives a factor of roughly 10. Since the light intensity goes with the square of the distance, this gives a factor of 100.
Now the moon has a radius of about 1700 km. Relevant for the reflected light is the cross section, which for the moon is circular, so we get approximately r² π ≈ 9.1 million km². Now we have to divide by 600 due to the considerations above, which gives a necessary area per mirror of about 15 000 km². Assuming square mirrors, this means that each mirror has to have a side length of about 120 km.
While still enormous, it's considerably smaller than the moon, let alone the sun.
The Tao of math: The numbers you can count are not the real numbers.
(Score: 0) by Anonymous Coward on Friday October 19 2018, @06:43AM
I'm chuckling on the inside thinking about putting something that needs to be precisely oriented, and it has a surface area of 15000 km^2, in a region of space that is not free of orbital junk. I imagine it will be something like a year before all of that turns into just more space junk.
In all seriousness, I don't see how anyone but a complete idiot would suggest this.
there's the circadian rythm mentioned above, there is the cloud issue mentioned above, there is a construction plus a forever maintenance cost, then there's the danger that despite forever maintenance, the gigantic object will (a) point somewhere it shouldn't and/or (b) fall on someone's head.
I'm not sure whether the UN can forbid it, but this is the sort of thing which should be forbidden.
(Score: 0) by Anonymous Coward on Friday October 19 2018, @02:13PM (2 children)
Thanks for crunching the numbers! I think you forgot to account for the fact that TFA says this will be 8 times brighter than the moon, though ;)
It's smaller than "The Moon" but considerably larger than many things we call "moons" in our solar system.
The largest mirror humanity has ever sent into space is just 2.5m in diameter. This one had a mass of about 1 tonne. There are plans (with endless delays) to up humanity's game by pushing to a whopping 6.5m, with a mass of about half a tonne (and this one is not designed for reflecting visible light, although I imagine it'll do a reasonable job).
Since those numbers assume the thing is directed... I don't even want to think about how big the reaction wheels to stabilize a mirror over a thousand times wider would be.
Hence the funny smell!
(Score: 2) by maxwell demon on Friday October 19 2018, @03:15PM
From my previous comment, emphasis added:
The Tao of math: The numbers you can count are not the real numbers.
(Score: 2) by bob_super on Friday October 19 2018, @10:01PM
To be fair, the biggest mirrors you mention are designed to be extremely precise.
At the other end of the spectrum, spy sats already grew to an estimated 100m diameter, probably not as precise because of the wavelengths they address.
Those mirrors would be closer to the spy sat structure than to JWST, especially because the chinese probably won't obsess about a few rays being reflected accidentally towards Mongolia.
(Score: 3, Informative) by FatPhil on Friday October 19 2018, @03:35PM
Thought experiment, which sensor gets more light:
candle
() |
---barrier------------------------- | perfect mirror
sensor < |
() |
----------------------------------- |
< |
() |
----------------------------------- |
< |
Distance to mirror seems to be more or less irrelevant in this highly reflective case.
Great minds discuss ideas; average minds discuss events; small minds discuss people; the smallest discuss themselves
(Score: 3, Insightful) by bradley13 on Friday October 19 2018, @07:20AM (4 children)
Why? What is the fetish people have about completely lighting up their cities at night? Local, on-demand lighting - sure. Generally turning night into day - WTF?
This article appeared on the green site, and one commenter did a very believable analysis [slashdot.org]. Put the thing in geo-sync orbit, and it's basically a thin-film, spinning mirror. Entirely achievable.
Aside from the technical aspects, there are two big concerns:
- Light pollution. Even if focused on a particular city, atmospheric scatters (and clouds) will disperse the light over a huge region. This will affect a huge area.
- Effects on wildlife. TFA gives lip service to this, but really, there's no way to know what the effect would be.
This is China, though. The Chinese government frankly doesn't care about anyone else's concerns.
Everyone is somebody else's weirdo.
(Score: 1, Interesting) by Anonymous Coward on Friday October 19 2018, @11:45AM
If they can properly move it around it would be in high demand for disaster relief. Usually the disasters knocks out most electricity/lighting, as such relief workers stop at night if it's to dark. This thing would be golden for that.
(Score: 0) by Anonymous Coward on Friday October 19 2018, @01:48PM
People light up the cities at night to prevent crime.
(Score: 2) by PiMuNu on Friday October 19 2018, @02:01PM (1 child)
Stops vampires. Nuff said.
(Score: 2) by bob_super on Friday October 19 2018, @09:55PM
But the epidemic of Werewolves is a bit of an issue.
(Score: 3, Funny) by The Mighty Buzzard on Friday October 19 2018, @11:11AM (4 children)
Not a single "That's no moon" quip. I expected better of you guys.
My rights don't end where your fear begins.
(Score: 0) by Anonymous Coward on Friday October 19 2018, @11:43AM
Terribly sorry to let you down you Sir ... came here to make that very astute observation but got distracted by the wonderful science and policy discussions somewhere along the way. Won't happen again Sir!
As a consolation prize I can say all this Fake Moon business smells like Fake News to me. I feel like killing some Bothan spies myself now!
(Score: 2) by DavePolaschek on Friday October 19 2018, @01:44PM
Sorry. My circadian rhythms were out of whack, and I didn't get a chance to comment before you had already become disappointed.
My bad.
(Score: 3, Funny) by nobu_the_bard on Friday October 19 2018, @02:28PM (1 child)
Other possibilities not yet discussed:
* Has anyone checked if maybe there's a lot of werewolf interest groups lobbying for this?
* Maybe it's the saiyans up to something?
(Score: 2) by The Mighty Buzzard on Saturday October 20 2018, @10:39AM
Ah, nobu, you restore my faith in the community!
My rights don't end where your fear begins.
(Score: 1, Informative) by Anonymous Coward on Friday October 19 2018, @02:19PM
pretty sure something similar got Mr Burns shot. Be wary of babies.
(Score: 3, Interesting) by legont on Friday October 19 2018, @06:37PM
https://en.wikipedia.org/wiki/Znamya_(satellite) [wikipedia.org]
It was a bad period for Russia to design anything. Let's hope Chine does better.
"Wealth is the relentless enemy of understanding" - John Kenneth Galbraith.
(Score: 0) by Anonymous Coward on Friday October 19 2018, @11:26PM
No way the chinamen can get their hands on that much green cheese.