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A Norwegian town built a giant mirror to deflect the sun (2017) (bbc.com)
199 points by happy-go-lucky 11 days ago | hide | past | web | favorite | 97 comments

This is sort of off topic, but this valley is pretty famous actually for being a strategic place in World War II (but not widely known) because it was a crucial source of heavy water.

If you haven't seen it already, I'd highly recommend the Netflix series "The Heavy Water War" (trailer: https://www.youtube.com/watch?v=_K3Ry2K4yNE)

Can also check out the old movie The Heroes of Telemark to get parts of the story https://www.imdb.com/title/tt0059263/?ref_=nv_sr_1?ref_=nv_s...

Oh dang, doesn't look like it's available in the US. It looks really good. I remember hearing about this part of history from this short doc: https://www.youtube.com/watch?v=eiy3b5HkUVw

Wow, this looks really good, it's available on Amazon Video, not free but looks worth watching. Thanks for sharing.

What's heavy water?

Water with the deuterium isotope of hydrogen, instead of the common isotope of hydrogen.

I'm fascinated by heliostats. Living in an apartment, I have always wanted to put up 'suncatchers' outside my windows and lead sunlight in through fibre optics to all the corridors and darker rooms. Something like this [1][2].

[1] https://www.parans.com/products/parans-luminaire-diffused-na...

[2] https://en.wikipedia.org/wiki/Light_tube#Optical_fiber

That parans product bringing natural light from the roof into buildings via fiber optics is pretty cool. I hope they get plenty of business.

Super cool. Have you looked into the price for the parans system? I can't seem to find it anywhere.

Well if you have to ask... it's probably incredibly expensive. The Wikipedia link list customers as international airports, universities, etc., and calls it 'quite expensive'. Probably out of reach for private homes.

That would be so much better than the two dozens of gas tubes currently lighting my office floor!

I grew up on the Great Plains of the US. I remember my first visit to Switzerland clearly. We get into this town in a valley with these massive mountains all around. I had this really strong sense of being confined, along with feeling like the mountains could come tumbling down on me at anytime.

It was strange, but also really odd when it felt like the sun would go down so early as it crossed behind the mountains.

I experienced serious anxiety the first time I drove through North Texas (flat as a pancake), having grown up in Colorado with the mountains ever present. It was a weird time in my life and... I was coming from Colorado, but I felt like I was going to slide right off the earth with such a flat horizon surrounding me.

I grew up in North Texas, and I still feel very weird by how flat it is.

Growing up I had the opposite experience. I grew up in a mountain valley in Montana and would go to Minnesota each summer. It was strange not having something on the horizon.

>It was strange not having something on the horizon.

But that is where the sky is supposed to be! ;)

I had that exact same feeling visiting the village where my wife is from in the mountains around Karpenisi, Greece. I couldn’t stop looking up and at times I felt this oppressive and menacing sense of claustrophobia (which I don’t usually suffer from). Am now more used to it but I wouldn’t want to live there. Born in Australia near the coast I’m definitely a beach guy and like others have mentioned I am very happy to see the sun on the horizon.

Not quite so existential, but I took a big hit to my ability to navigate when I left Chicago. Aside from the obvious (grid of streets), I didn't realise why, until I was back once and a non-Chicagoan said she was lost. "How can you be lost?" I asked. "The lake is over there, so that's east."

My startup has been working on a virtual skylight that produces a pretty good proxy for feeling like you are outside in the sun even if you are underground. The key invention is in collimating a large area light source so it travels in a straight line and appears to be miles away. We will be showing it at a conference in Philadelphia next week if anyone is interested. Https://Innerscene.com/products

Interesting. How do you differentiate yourself from CoeLux, which has been doing a very similar thing for a few years now?

Coelux has a nice product, compared to it ours takes up 14 times less space in the ceiling for the same viewable area, the sun is at true infinity so you can create arrays where the sun seamlessly follows you as you walk around, it has dynamic spectrum and dimmable, price is half, weighs ~10X times less so structural install shipping is easier/cheaper, more energy efficient, programmable, just to name a few...

I had to reread this twice to realize yours is the 14x smaller product not theirs. You should improve you comma game.

I haven't seen either product in person, but from looking at youtube videos of both, it seems like CoeLux has a clearly defined, properly round sun, while with your product, the sun looks fuzzy and cross-shaped, like viewed through a diffraction grating [1]. Am I correct in this characterization?

[0] https://youtu.be/EM8psaLBsr8?t=112

[1] https://youtu.be/_GYpxeum12U?t=138

Good observation. That is an older video from a prototype - take a look at this: https://www.dropbox.com/s/7dwa7mj39rpely6/facia%20and%20mull...

I'd say they are pretty similar, Coelux may be slightly less diffusive but it's beam divergence angle is pretty high so it doesn't hold up for very much distance compared to ours - you can see it spreads out into a non-rectangular shape on the wall.

Fascinating. Is it correct that with both implementations, you cannot move the virtual sun around - it's always shining from the exact same angle?

Likely, but it isn't too hard to imagine how that could be fixed for an even greater cost. I wonder how the two products work.

I'd probably shine an array of narrow-beam LEDs through a sheet of aerogel. (the aerogel disperses the blue light) If the LEDs are on long horizontal rods that can rotate, that lets the angle change. You'd need the beams focused down to about half a degree, with at least a dozen viewed in a circle of that size from the perspective of a tall person under the light.

Another way is just an RGB array, with different lenses on the different colors. The blue gets a fish-eye lens, while the green and red get focused down to about half a degree. Again there can be rods that rotate, and at least a dozen LEDs need to be in a circle of half a degree when viewed by a tall person under the light.

the sun follows you in the sky as you move around but it's angle doesn't change throughout the day.

so... why on earth are you releasing your product if it's that much worse than theirs?

edit: oops! I read “it ours” as “ours it” somehow!

It took me a few reads through, because I had the same reaction you did. No, the commenter is claiming those benefits for their own product, and just says their competitor's product is "nice".

wow that's quite amazing! could be worth it even at 10k+

here is a direct link so people don't have to copy/paste https://innerscene.com/products

What is the price range?

In some areas we sell through Lighting Agencies, Distributors, and contractors who will set their own prices and markups. If you let me know where you are located, I can give you a number - but as rough guide, in the USA it is somewhere around $15-$20k for a 40x20 inch unit. We will be announcing a new version next week.

> $15-$20k

I was excited for a while there, but I guess I'll continue on my path to becoming Gollum

If you get this down to around $5k I bet you'd have a much larger market of apartment dwellers such as myself. Any hope of getting there in the next few years?

How much traditional lighting could that 40x20 panel replace, and what is the expected lifespan? (Also is the spectrum close to a true black body?)

In a sort of related/inverse vein, I thought the engineering at play here was pretty interesting. 96 million shade balls on a public water supply reservoir:


I just find it hilarious that they do this on the tail of wanting to ban plastic everywhere.

Why yes, please take these black plastic balls, coat them in a known carcinogen, place them over drinking water, and let them bake over the sun[1].


[1] https://en.wikipedia.org/wiki/Shade_balls

Fortunately it's because the kind of people that want to thoughtlessly "ban plastic everywhere" are thankfully not making decisions about our water quality.

The entire shade-ball program was created to mitigate high levels of bromate which were forming when sunlight interacted with chlorinated water. Bromate is an _actual_ carcinogen; as opposed to the carbon black coating on the shade-balls which is only carcinogenic when inhaled as dust (otherwise the activated charcoal in all those drinking filters would be pretty bad news).

AFAIK they aren't even coated in carbon black the HDPE is mixed with carbon black (same as many other black plastics/rubbers) and then formed into the spheres.

> ...on the tail of wanting to ban plastic everywhere.

One-time use plastic bags and more recently drinking straws[0], not all plastic everywhere. The world can’t run without plastic.

Your own link says the recycleable (fwiw) balls have a 10 year lifespan.

...and the carbon black is a carcinogen if inhaled as dust, but is used (in part) to reduce a suspected carcinogen (bromate) and made for the sun (...with carbon black additive to protect the plastic from ultraviolet radiation.)

It’s in your cited article. What would you propose as an alternative?

[0] https://en.m.wikipedia.org/wiki/Phase-out_of_lightweight_pla...

Plastic was commercialized 70 years ago. The world ran fine for a very long time without it.

With significantly fewer people, most of whom (on a global scale) lived significantly worse and shorter lives. Like it or not, the modern world is built on plastics, and undoing that will require either major technological jumps from what we have now, or a LOT of people dying.

The world ran a long time with iodine supplements, antibiotics, water fluoridation, doesn't mean we should go back to the dark ages.

> coat them in a known carcinogen

That's actually the opposite of what's going on. From wikipedia:

Starting in mid-2008, the Los Angeles Department of Water and Power (LADWP) deployed around 400,000 balls in the Ivanhoe reservoir with the main objective of preventing the formation of a carcinogenic chemical, bromate, which forms when naturally occurring bromine reacts with chlorine in the presence of sunlight.

“The shade balls used in the Los Angeles project are made of high-density polyethylene (HDPE) with carbon black additive to protect the plastic from ultraviolet radiation. Adding carbon black also prevents the formation of bromate, a suspected human carcinogen.


The black coating on the balls, called carbon black, is a petroleum derivative which is classified as a carcinogen if inhaled as dust. ”

So you have balls made with a known carcinogen (if inhaled as dust) to prevent formation of another carcinogen formed in water. I’m guessing they researched the risks already and it’s a net positive.

You forgot the part that the color is added in form of a masterbatch.

You generally don't inhale the water that these plastic balls are in.

Rjukan (the town from the article) is also a great destination for ice climbing. Lots of frozen waterfalls only a stones throw from the road.

Only a couple of hours drive from Oslo.

In case you need an excuse to visit.

Also some of Norway's most reasonable real estate prices, with detached homes starting at less than $100,000.

I used Google Translate's camera feature to translate a few estate agent window ads while I was there and genuinely assumed I must have been looking at the deposit prices given the price of everything else in Norway.

If you were anywhere else, you'd probably see the deposit price and figure it was the full price of the property :P

Actually, things are not as bad as in Seattle/SF/LA/New York, but modest things are still very expensive in our cities.

There are home versions of these heliostats too, I always thought it would be a nice home improvement. You could make a new sunny room, sunnier garden, or a warmer patio.

Just googling, $2,000 gets you 1300 watts of heat. Or 115,000 lumens. (100 watt incandescent is 1600 lumens). The mirror part is about 4 feet x 4 feet.


Really neat. I can see mounting their $300 mirror on my apartment balcony to extend my “direct” sunlight a couple of hours.

It's a neat idea but I wouldn't say "three mirrors, each measuring 17 sq m" is particularly "giant".

Depends on how you think about it, relative to the mirrors that were there before they are collosal. I do take humbrence with the author's use of the word, "deflecting". Sounds like they're trying to divert the Sun's wonderous glory away from their town. Reflecting is the word, praise the Sun.

Deflect is to change direction. It's why you can deflect a puck in hockey into the net. Don't know why people keep reading it as a negative.

Deflect most often is used in a sense of deflecting something away from something else. e.g. to deflect a bullet. That would mean away from its target, not into a target.

In English there isn't a general word for altering a trajectory into an object. In this case however, reflect is precisely suited to what mirrors do to light and doesn't have the confusing inverse connotation of away. You reflect away from something or onto something equally well in English.

> In English there isn't a general word for altering a trajectory into an object.


Also: Reflect (you know since it is a mirror). Bounce. Redirect. Bank. Alley oop. Ricochet.

You aren't the hero we need, but you're the hero we deserve. I'm changing my vote from, "reflect" to, "Alley oop".

although it’s not as common, “inflect” denotes changing direction toward a target.

yay for the elegance of latin-based prefixes! =)

I don't mean to be a grammar Nazi, but by "humbrence with" do you mean "umbrage at?"

In a neat coincidence "umbrage" and "umbrella" apparently share a common origin in Latin "umbra" (shade).

Please don't downvote this guy. As a non-native speaker, I learned one nice word and a bit of trivia about it. It certainly adds to the discussion, as without the explanation I wouldn't know what the GP wanted to say.

Thanks for your comment. I was disheartened to see the downvotes. I'm glad it was of some use to somebody!

I took the initiative to divert the conversation into semantic territory, and invited the Spelling-Stasi into my home. So as far as I'm concerned you can have a cup of tea while you're at it. And I'm glad you pointed out the serendipity of the mistake, so I can attempt to claim it as as my own clever play on words.

The Italian town of Viganella installed mirrors in 2006 (Rjukan was in 2013).


I’ve been there. It makes a few m2 in the town square slightly lighter. Neat but certainly not mind blowing.

On a side note, having lived in a northern city famous for its bad weather (Dublin) I always wondered why instead of building with dark red bricks they don't coat the buildings with reflective material. And the sad part is that I bet it's not done because it's for the benefit of the neighbors on the opposite side of the street (though of course, it could be reciprocal).

I spent part of my childhood in a similar place in far northern BC. The north-south orientation of the valley we were in prevented much winter sun from hitting the town. On top of that, there was an asbestos mine nearby and sometimes when they were blasting up at the mine site, dust would settle on the town. Once the mine closed, the town was basically erased and everyone left.

Pretty sure this has had significant discussions on HN in the past, but I can't find them. Anyone?

(The purpose is just curiosity. Reposts of a story are ok after about a year, as the FAQ explains: https://news.ycombinator.com/newsfaq.html.)

I think China was looking at putting up satellite solar reflectors to avoid the electrical cost of night time illumination in cities. If that tech gets cheap enough you could in theory target a town/agriculture like this to give it an effective latitude shift towards the equator.

That doesn't really pass the sniff test... distance to GEO is 36,000 km, the sun is approx. 0.5 degrees in angular size, that would mean a mirror with a diameter of 314 km in GEO. We do not have the technology for that.

2 36000 tan(0.25 deg) = 314 km

The people congregating in the sun spot in the middle of the town square remind me of this Portlandia sketch: https://www.youtube.com/watch?v=G-ppr9LDaQE

I've always wanted my own heliostat(s) as I think they'd be more useful than solar panels (at least for me) - sending concentrated sunlight and heat in through your windows.

But can't find any good design/plans for DIY or anyone selling one.


I have the vacuum mirror focusing upgrade pack.

Works really well and I roughly calculate that you get 80% of the growing power from the sun as direct light.

I use it for a part of the garden that never got light due to building and trees and was always soggy and damp. Nothing grew there very long, now I maintain native wildflowers and a butterfly garden there.

It’s really cool. The heliostat follows the sun mechanically and also can tune in the focus with a vacuum system.

IMO, $2500 seems extremely expensive for focusing 1.45m2 of light, especially when you can get at least 2.5kW of solar panels for the same price.

It’s a completely different technology that’s solving a different problem. And sun tracking is more complex when you are reflecting onto a fixed point as opposed to simply pointing the surface (in the case of solar cells) toward the sun.

Here’s a cheap home version under development, funded through indiegogo. I was a backer and am hoping to receive one soon but it’s been a long wait so far:


I hope they don't try to steal candy from any babies!


It's like a giant SAD lamp, only you share it with other people

They should move it from house to house and make it an occasion to invite the next neighbors to dinner :)

Perhaps large, light weight deflecting mirrors in orbit could help with climate change.

Reflect not deflect :-)

Simpsons did it

I live in sunny California but I still have problems with not enough sun. I used to be a cyclist and triathlete, being outside for many hours a week, and now I am doing maninly dancing. I am inside way more than I used to be. I can feel when I need more sun. Incedentally, I also had a recent physical where they measured that I had a vitamin D deficiency.

They said a lot of interesting things in this article related to the sun, so I leared some new things. At the same time I am surprised about some things they did not say.

I'm not an authority on the bodies need for sun, but I will give my non-scientifci observations. If some one finds this interesting they should do some additional research on the topic before they do anything I did, rather than just trust what I write here.

One thing that really interested me was an article I saw here on Hacker News a several months ago. It said it is well known people with higher vitamin D levels had some health bvenefits. However, one particular study found that giving vitiamin D supplements did not seem to give the same health benefits. The authors concluded from their results that people who have high vitamin D often get this from the sun, and the sun gives them a different result from just taking vitamin D supplements.

I tried going to a sun tanning salon and found that did make me feel a subtle "high", as if I had been out on a sunny day. (Your experience may very.) From what I understand it is UVB that is responsible for this, the "bad" UV. It is considered bad because your body does not shield against it and it does not cause you to tan.

General tanning salons want to give you UVA. The expensive machines limit your UVB exposure, and the cheaper ones give you more UVB (salons often have different options for beds). You want to go to the cheaper option. I used beds at tswo salons with 5% and 6% UVB, for reference. They should know the UVA/B statistics for the machines.

As far as length of time, you don't need to go that long. The point is not to get a tan necessarily. I found that i would get more tired if I stayed in too long, so there is sort of an optimal time, for me at least. (I am very pale, by the way.)

I also noticed that the sun tanning bed was not enough. It is almost as if there are two effects. I feel good from the tanning salon, but at the same time it feels like there is something missing. I also need to go outside, I assume to get visible light.

To repeat above, these are not scientific results. I find this seems to work for me, and that is good enough. I would not suggest someone trust what I say here as authoritative, but hopefully it can be an inspiration to look into this if you have similar problems.

FYI, one thing I want to look into as a result of this article is timing of getting visible light. I do know that if I wake up in pitch black I have trouble getting out of bed. I would link to get more bright light in the morning right when I wake up and see how that effects me.


Deflect means to shield an area from sun; this project is to bring sunlight into a perpetually shaded area.

To my ear 'reflect' could also mean to shield from. More so, in fact, because it tends to imply a 180 degree angle where 'deflect' implies something else. Of course people have many different associations.

Thank you for mentioning that, as a non native speaker I was a little confused.

Deflect (verb) cause (something) to change direction by interposing something; turn aside from a straight course. "the bullet was deflected harmlessly into the ceiling"

Although you are correct and GP was mistaken in their definition, `reflect` fits better here.

Definition of reflect

transitive verb 1 : to prevent passage of and cause to change direction

// a mirror reflects light


Definition of deflect

transitive verb : to turn (something) aside especially from a straight course or fixed direction

// armor that deflects bullets, deflecting a question


With deflect, something is simply being diverted, whereas with reflect, it's more intentionally being aimed somewhere. This is the nuance I feel innately, although at this point we're splitting hairs I think.

Yeah. Tough questions are deflected. Glory is reflected.

Deflection is typically used when the would-be target is protected from the incoming object. Reflection is when the never-was target is now a target.

Although you are correct and GP was mistaken in their definition, `reflect` fits better here.

I don't see why deflect isn't acceptable. Previously the sun was shining on the hillside below, now it's been deflected to the town square.

What I understood is just that reflect seems to fit better here, given the most common use cases for the word.

deflect is not appropriate in that sentence because it means that the sun itself would be moved.

Ray Mears documentary "The real heroes of Telemark" is also worth a look.

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