Flagstaff, Arizona, switched to LEDs without giving astronomers a headache | Hacker News Reader

Flagstaff, Arizona, switched to LEDs without giving astronomers a headache

arstechnica.com

218 pointslnguyen95 comments

> The bulbs Flagstaff relied on for most of its streetlights were low-pressure sodium—a variant that only emits light at a single wavelength (589 nanometers) near that yellow color, producing something resembling candlelight.

Even 10 years after college I distinctly remember the look of Flagstaff at night. Namely because the city was effectively grayscale and it was beautiful.

By the way, if you don’t know, Lowell Observatory in Flagstaff is where Pluto was discovered.

> Even 10 years after college I distinctly remember the look of Flagstaff at night. Namely because the city was effectively grayscale and it was beautiful.

San Jose used to look that way too. There are still pockets of LPS lights here and there, but since most makes are not commercially available anymore as of this year you can expect they'll vanish fairly quickly.

Such a loss, LPS streelighting was very good. I hope the narrowband amber LEDs are a commercial success.

Anyone know where there are fixtures with them available in small quantity? ... I stocked up on LPS bulbs before they went unavailble, but they won't last forever.

I found that the LPS lighting in San Jose was very close in color to yellow traffic signals, which made it sometimes confusing (and therefore more dangerous) to drive there after dark.

Aside from the sky glow aspects, I really dislike cool blue lighting. I've just had my office upgraded to warm white LEDs and it's really noticeable every time I walk into a colleague's office with "cool daylight" coloured lighting.

My friends call me The Illuminazi for my habit of swapping everyones fluoros and compact fluoros our for 2700K ones.

It’s an expense I’m happy to pay.

One of the best benefits of working from home for me is that I can have the lighting I prefer (4000k, with both my light and screen set to the same color temp). But if I ever go back to an office I'm stealing this idea.

Have you ever tried blue blocking glasses?

Personally I’d prefer rose-coloured glasses.

Even just a 10% brown on your regular glasses makes a noticeable difference.

I did try blue blocking glasses awhile back, didn't seem to work well for me, but I should try them again since I've become more aware of how things affect me now.

I very much prefer working in cold white and whee I relax and rest there I prefer warm white. I think cold white helps me stay awake and more alert. It all might be s placebo of course.

No that's actually proven science; white or blueish lights help you wake up / stay awake, whereas orange / red lights will help you relax / sleep / produce melatonin. It's why F.lux and the native solutions shift screens to red at night. It's really quite stark a difference if you turn that off at night.

Yes. It's also why you have the Blue Light Filter on your android phone (which I have always-on).

I have it always on my iPhone and triple click home makes it even redder.

It's far from proven science.

There are lots of studies and articles discussing the affects of blue light on melatonin and sleep

https://www.ncbi.nlm.nih.gov/pubmed/30311830

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2717723/

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2831986/

https://www.health.harvard.edu/staying-healthy/blue-light-ha...

https://www.sleepfoundation.org/articles/how-blue-light-affe...

https://www.healthline.com/nutrition/block-blue-light-to-sle...

https://brighamhealthhub.org/prevention/using-light-emitting...

https://www.scientificamerican.com/article/q-a-why-is-blue-l...

https://www.ncbi.nlm.nih.gov/pubmed/30311830 No real conclusions. It's appears to be a study aimed at making future studies better "The review enables further development of an evaluation method of light pollution in LCA regarding the light-induced impacts on human circadian system."

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2717723/ No definitive conclusions: "Additional laboratory-based and field studies are still necessary to better understand some features of the human circadian response to light. We are only beginning to understand how prior exposure to light affects the subsequent response to a light stimulus, and our understanding of how light exposure can affect the period of the human circadian system is also limited (135)."

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2831986/ Seems to be a review of other research by a journalist

https://www.health.harvard.edu/staying-healthy/blue-light-ha... news article, not science

https://www.sleepfoundation.org/articles/how-blue-light-affe... News article, not science

I'd go through the rest but it's time for lunch.

That's a different claim.

Blue light can interfere with Circadian signalling. Nothing new there, though the issue is under-recognized.

What is being claimed is that blue light is good for staying alert, presumably during the working day. That's more tricky, and would argue that blue-light is reinforcing some aspect of the cycle or has a unique physiological effect.

This is, however, unlikely; blue light serves primarily to entrain the clock, i.e. to keep it in period and phase with the daily cycle. Without this light signaling, your clock will 'free run' which is a cycle that is slightly longer than the 24 hour cycle. Crucially, it's important to note that the clock functions just fine, it just no longer adheres to a strict 24 hour cycle.

The idea that more blue light throughout the day, beyond the morning zeitgeber, would have an effect on performance is very different idea. To my knowledge, there is not any evidence that this would be the case, and it is contrary to my understanding of Human Circadian Rhythms.

This is backed by science. Philips Hue uses warmer color temperatures for relaxation presets and colder brighter ones for energization. Anecdotally, the "energize" setting is too much for me. I usually just use Relax, a nice sunny yellow, unless I really need to focus and gear down hard.

I have a few Philips Choose Scene, or Scene Switch, whatever they’re called this week.

They cycle between warm and cool when switched off and back on, but aren’t a connected device.

I believe the latest incarnation has a dim and even warmer setting as well.

> This is backed by science.

It wasn't at all when I looked into it last year. Can you point me to new research in this area?

Look at bulb spectra: https://www.researchgate.net/profile/Fawzia_Abdel-Rahman/pub...

Any reptile or bird owner can easily attest to the effectiveness of full spectrum light on a living being.

That's why I'm pretty happy with my smart lights, they can change kelvin rating, so while working it can be blueish, and later on more warm.

For cool daylight 5500K lamps to look natural, they must give very intense light, like a slightly overcast summer sky.

Few people do this outside a photography set, though.

My wife and I have replaced pretty much every light bulb in our apartment with candle light style bulbs for this reason. During the day we just have sunlight from the windows, but at night these are much more relaxing.

https://www.lowes.com/pd/GE-Vintage-60-Watt-EQ-G25-Warm-Cand...

> “What's left is green,” Hall said. “And so you stand under this and it's like the zombie apocalypse, because everybody's green. They've gone to these in Hilo, Hawaii, and we were standing in a parking lot trying to talk to each other, and it's just like straight out of Night of the Living Dead.”

This is not my experience. In The Netherlands green LED's are applied more and more often for streetlighting in rural areas and surveillance of building construction sites (light pole + camera).

First time encounter takes some getting used to, because we are so familiar with orange Sodium hue. But I find they make the night landscape more peaceful and serene looking.

Green spectrum is perfect for the human eye. You see more detail and sharper focus, seems to me (compared to orange). Apparently its also good for nature. Not only to insects, but also birds not getting distracted.

Orange is a lot better if you want to keep your night vision and be able to see into the shadows (or e.g. look at the stars with your unassisted eyes).

Contrary to popular belief, cyan is better for night vision. Your rods are most sensitive to cyan, so you can use much dimmer cyan light than you can use red/orange light.

http://stlplaces.com/night_vision_red_myth/

The question is not what you can see best with the least energy, but what kind of glare in your peripheral vision will cause bright-adaptation.

Your page there seems to be based on its author looking at the sentitivity curves for rods and cones and then speculating, but not as far as I can tell based on experimental evidence about how well the eyes stay dark-adapted.

Edit:

Moreover, the type of lamps appropriate for medium-bright street lighting and the type of lamps appropriate for briefly turning on to dimly see your camera gear while you fiddle with it when you are out taking night-sky photographs are quite different.

Disclaimer: I am not an expert on triggers for brightness adaptation. I should try to hunt up some research papers sometime.)

Looks like https://www.osapublishing.org/josa/abstract.cfm?uri=josa-41-... is a reasonable place to start looking into the citation graph. https://scholar.google.com/scholar?cites=4424978361272323417

Or maybe https://www.sciencedirect.com/science/article/pii/S004269897... https://scholar.google.com/scholar?cites=1469411636090158094...

I agree, I work in green light a lot and it actually gets kind of addicting. It’s nice, very soothing and you can concentrate on what you are doing.

This year we (our family) have the expressed goal of renting a cabin far off from major cities (partly) so our daughter will get to see a night sky full of stars.

We live close to an airport, so atm she gets excited by seeing more than 10-ish stars, so I'm looking forward to seeing her reaction :). Also, once seeing and pointing out a satellite was a highlight :).

You might want to show her the International Space Station. It's very bright and NASA offers a notification service [1] for overflys at your location. Having people on it might give bonus points. Extra info: on November, 2nd, it will be the 19th year of uninterrupted human presence off the Earth.

[1] https://spotthestation.nasa.gov/

PS: you might want to watch out for the next group of Starlink satellites from SpaceX. The chain of sparkles moving silently over the sky was absolutely amazing to watch. It's most likely not dark-sky compatible, though :/

Another helpful site (be sure to try the green button)

https://james.darpinian.com/satellites/

One thing I'm thankful of when living and growing up in Australia, you could clearly see the night sky and all the stars there if you went to the beach or the hills. Far less ambient light pollution, such a beautiful night sky.

I just hope it doesn't get spoiled by all those constellations of Internet Satellites.

Australia also has the advantage of seeing more of the galactic core during the whole year. On the northern hemisphere you can see it only in the summer and even then less than Australia.

Australia has far less air pollution, too, given the low population and relatively tiny strip of populated areas along the coast.

The skies in Freycinet National Park in Tasmania were the most stunning I've ever seen in my life.

I don't knowknow where you are located, but Wyoming has some dark skies and beauitful camp sites if you can make it that way.

A guy I went to bootcamp with in my Army days was born and raised in the city. One of our first nights in the field I remember he was astounded at the number of stars. I guess like your daughter, he had only ever seen a few at a time his entire life. He actually thought shooting stars were something that Hollywood contrived. So myself and another guy stayed up a little bit with him until he saw one. His mind almost exploded.

A great way to "explode" the mind routinely is a pair of 15x70 binoculars with premium optics. The effect of handing them to someone, nudging them to Orion's belt or Pleiades, etc, and hearing the inevitable expletive never gets old. Continues to work on self indefinitely, for me.

Recommendations for a good pair?

Entry price will be near $400 for what I was referencing. Mine were Garrett Optical (Signature Series), which I think is no more. However, the build is almost identical under different brands, eg Orion Resolux. The features in these porro prism 15x70 models, for an equivalent, should be:

Fully multi coated; waterproof; bak-4; individual diopter focus.

Garrett was meticulous in testing collimation before shipping, which is critical for quality viewing at higher magnification. I had the Resolux too, but in 10x70, which were great, but not as wow.

When I can afford it, I will buy the Fujinon Polaris 16x70 ($900), unless I stumble into great wealth, in which case I may consider the largest pair of roof prism Leica available.

The well-built porro style binos are best equipped with a monopod for extended viewing, due to their weight. Roof-prism binos are lighter, but much more expensive and rare in large apertures, ie objective lens. I briefly had a pair of Zeiss Victory (roof prism) 10x50 which were phenomenal, highly portable and stunningly clear, but simply couldn't provide the wowness of the 15x70. Ideally, I'd have both.

Edit: Whatever you choose, my advice is to never even consider "zoom" as a feature in any pair of binoculars. It is tempting in concept, but almost never conducive to quality.

Does this even work in suburban areas, where Orion and the major stars are all pretty clear, but the sea of dimmer ones are blown out?

I find they work quite well even in suburbia. Of course, they work best elsewhere, but are very much worth having almost anywhere, for me. I have been been amazed many times after pointing my binos to an apparently void area of sky and seeing what was hidden to the naked eye.

There is nothing like a moonless winter night (<20 below) in far rural Minnesota. Either you get a vast number of stars or you get the Northern Lights. Eastern North Dakota is probably a good choice as well.

> Older streetlights are high-pressure sodium bulbs, which produce a warm yellow glow around a color temperature of 2,000 K... Many of the LED streetlights on the market have much cooler color temperatures of 3,000 or even 4,000 K.

I feel like referring to 2,000 K bulbs as “warm” and 5,000 K bulbs as “cool” has got to be one of the worst screw-ups between scientific terms and common terms in English. And probably a missed opportunity to embed some latent understanding of thermodynamics in the broader culture.

Red embers (~1000K eigen radiation) are hot, blue(-ish) ice (lit by 5500K daylight) is cold.

..go figure!

Remember that CCT color temp (K) is about the equivalent ideal blackbody radiator. Think "white hot"

I don't remember that, can you elaborate further?

Color temperature refers to the color of an ideal black body radiator at that actual temperature[1]. And the hotter a black body radiator gets, the more blue the light output is. ~5800K is the color of sunlight because that is the physical temperature of the surface of the sun.

Which happens to unfortunately be the exact opposite of the much older color theory notion of warm (red-ish) and cool (blue-ish) colors.

They both use words related to temperature but actually have nothing to do with each other.

[1] http://www.techmind.org/colour/coltemp.html

Warm/cool color theory predates the kelvin scale, so it might be more accurate to say you feel Celsius' flipping his original scale was the screwup? But as how it is now makes that much more sense, and since you couldn't really have a kelvin version of such a thing anyways, maybe chalk it down as just one of those things.

In any case no one could convince me to call the color of fire and the sun anything but warm, and that of snow and sea cold.

>In any case no one could convince me to call the color of ... snow and sea cold.

How about the color of a gas stove flame?

Maybe we should have called them "warm white" and "hot white" instead.

Yeah warm to hot is good but again runs into clashing with things established before much had been said about black-body radiation.

Just because it might not be conductive to a neat 1:1 mapping with scientific common sense doesn't have to mean either should change. Quirks are fun!

I'm used to it myself, but I work in architectural lighting and I can't count how many times I've had to explain that "warm white" is the low temperatures and "cool white" is the high temperatures. It's a frequent nuisance for me, but not a huge deal and we're stuck with it.

If we were going to make people put in some effort and redefine fix stupid quirks that exist out of historical convention, I'd put that effort toward adopting metric instead of switching words for shades of white :P

It's not like switching cool and hot would make sense either, 2700K (orangeish) is 4400°F and 5000K (blueish) is 8540°F. Neither of those is anything near a "cool" temperature. "Blazing white" and "inferno white"?

Exactly what I mean, it's never going to make perfect sense, so trying to adapt two separate meanings to gel slightly better seems futile.

I would argue the US still not being on SI is a bit more than a quirk. I wonder whether you'll have completed metrification by the end of the century.

If we're replacing cool white, "blue white" is the best term I can think of... or perhaps "snow white"?

Yeah, it makes total sense, historically, how we got to this point. I just like to take a step back sometimes and appreciate the silliness of language. Not trying to assign blame, but just notice: hey it's kind of screwed up that totally opposite descriptions of a temp are both correct depending on context.

"This 5,000 K light bulb is cooler than this 2,000 K light bulb."

"This 5,000 K molten iron is hotter than this 2,000 K molten iron."

Yeah, some kind of lede/lead type separation would make sense. But in a sense there already is one as K barely sees layman usage outside color temp, so your second sentence isn't likely.

There is no misshap.

On the one hand, we (or perceptual psychology) deem red a warm color, probably by learned or ingrained association with fire. And the blue part of a flame is actually hotter, so OP has a point. The very word blue actually stems from a sense shiny, bright.

On the other hand, the watt/lumen ratio of red is higher than blues', I believe, and both are much higher than greens'. Simply put, if lower wavelengths pass less energy, then waves at the same energy but different frequency must have higher attenuation if closer to red. Alas, I'm not sure what velocity means in optics.

This is more illustrative with Music: A bass that you can hear and feel carrying the high tones must have a lot of energy.

Not sure what you're trying to say.

There's no inherent watt to lumen ratio for anything as far as I'm aware, but mainly, how would the other things you mention negate the fact that cool/warm colors are indeed flipped compared to temp?

You're saying blue, having higher energy and matching red with fewer photons, makes sense to describe as cooler because it can put in less effort?

Definitely haven't heard that one before.

Edit: there's obviously a language barrier but that's what I took "no mishap" to mean, that you disagree with us.

You have no idea how Lumen is defined, do you?

It's an association problem. Fire=warm and snow=cold. Fighting unconscious links between words like these is near impossible imo :)

Are there no orange/yellow LEDs? Seems odd, since LEDs were red long before other colors were available.

Years ago, Pickett slide rules were a greenish yellow, which, according to their advertising, was the color that provided the sharpest visual acuity and comfort for the user. Maybe that would provide the best vision for the least lumens as well.

>...was the color that provided the sharpest visual acuity

I think it changes considerably based on the environment and the user. I do some 10 meter air rifle competition, and the sighs have filters in them to let you choose different colors. I can notice a big difference based on the lighting, and at a competition different people will have settled on different colors.

That's not only dark-sky- but also insect-friendly! Insects are attracted by blueish lights which, for example, the old sodium pressure lamps did not emit. (The orange light you might remember from those were the 589nm double spectral lines of sodium.) LEDs can/do emit blueish lights and should be picked carefully for outdoor lighting.

It’s a real shame that Phoenix metro is going to ruin everything for Flagstaff and Tucson in the not-too-distant future by refusing to implement any light limits at all.

How is that going to ruin things for Flagstaff? Phoenix is far away from Flagstaff.

> The Greater Phoenix area casts a nighttime arc of light over most of Arizona, extending more than 200 miles in each direction.

https://www.azcentral.com/story/news/local/arizona/2014/09/0...

Dark skies require a pretty high radius of dark landmass. For an estimate of the extent of this, try seeing the areas around major cities here: https://www.lightpollutionmap.info/

I live in Dallas-Fort Worth and grew up near Amarillo, TX. In high school I regularly drove a few miles (like less than 5) away from the city to look at lights. I've noticed in DFW you've got to get much much further away from the city. I can't really put a number on it, but I know even 20 miles out of town you can still only see the brightest stars.

Former astronomer here. From Mt. Graham in Arizona you can see the sky glow from Los Angeles. Phoenix is a lot closer than that.

I can't stand the orange glow of old street lights. You can see so much better with 4300k vs 2000k http://i.imgur.com/JsSCfFp.jpg

https://www.youtube.com/watch?v=U1dMlVwUsrA

There are places where I would strongly disagree with you, like my home town Assisi, in Italy [0].

But for everything else, you are quite right.

[0]: https://www.flickr.com/photos/126687494@N08/15010177954/

Exactly, I really don't know why we bother to put up lights that aren't enough illumination to do without headlights/flashlight and most of the light is just wasted to the sky and illuminating the sides of buildings.

The light distribution from old LPS/SOX fixtures was usually all over the shop. A crucial benefit with LEDs is that their output is much easier to control thanks to their small size, and accordingly most lanterns have 'cut-off' optics.

Flagstaff is the only city so far I've actually been able to see the milky way. We just got lucky one night while visiting as the sky was clear at the Lowell observatory.

> Another way to do it is with phosphor coatings on the LED that absorb light of one wavelength and emit it at another wavelength. Lights known as phosphor-converted amber (PCA) shift all the light out of the blue and into the yellow part of the spectrum at the cost of some efficiency.

Is this essentially an LED filament bulb? I've replaced all lights in my house now with LED filaments because they look more natural and are omnidirectional.

It has nothing to do with filaments and is all with the phosphor coating. Standard white LEDs intentionally bleed the base blue LED through, whereas PCA LEDs do not.

Lumileds is the primary innovator for PCA (and other offshoots). https://www.lumileds.com/uploads/571/DS144-luxeon-c-color-li...

Seattle replaced all streetlights with LEDs a few years back. It too bad that they are the blue lighting that the article mentions, which absolutely makes viewing anything in the sky a lot harder than it already was. I'd love to go back to Flagstaff some day to see the lighting in person.

They also have a dark sky ordinance where various rules, to point lights downward, covers over the tops of them, etc.

More cities should do this, it makes for lovely night skies where you can actually see the stars.

Do the new street lights only have LED's, or do they also have cameras and microphones like the ones installed in San Diego and a few other cities for machine learning?

https://imgur.com/oYYRmHl.png

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