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Simple streetlight hack could protect astronomy from urban light pollution

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Re: Simple streetlight hack could protect astronomy from urban light pollution

#131

Post by Obscurity4340 »

Zardoz84 wrote: post #128
Obscurity4340 wrote: post #120

Earlier quoted context omitted.

Its often the most offensive shade of bright white fluorescent-like LED. Why can't they do the orange one that lets everyone be ok seeing light at night and sleeping to tell the tale

LED it's more power efficiencient . However, there are LED light bulbs that have some kind of filter that makes it more ambient and astronomy friendly. Normal white LEDs are a nightmare for astronomy, because his light spectrum it's hard to block with any kind of "anti light pollution" filters.

Its basically prison light, I would only ever use it to wake up in the morning. Anybody who seriously uses it to save money in a frequented space or in place of proper soothing ambient light is a bit off in my view. It makes me unhappy and feel beyond agitated whenever I am compelled to be around it.

Re: Simple streetlight hack could protect astronomy from urban light pollution

#132

Post by perilunar »

nativeit wrote: post #50

Astronomers already use a variety of optical filters, and LEDs tend to be “spectrally peaky”. If we standardized the spectrum used in street light fixtures, it could very easily be filtered out. I believe this has already been done when most street lighting was sodium lamps, which is also a very narrow spectra.

We could just use yellow LEDs. They have almost the same wavelength as low pressure sodium lamps (585 nm versus 589 nm).

Re: Simple streetlight hack could protect astronomy from urban light pollution

#133

Post by perilunar »

the_third_wave wrote: post #32

One of the advantages of low-pressure sodium lamps is that they emit nearly all their light in a narrow spectrum which is easily filtered out. This leads to non-existent colour rendition - everything is seen in shades of warm orange - but given that these lamps have been used for decades without too many problems this seems to be a surmountable problem, at least on motorways which are a major source of light pollutio…

Yellow LEDs have almost the same wavelength as low-pressure sodium lamps.

Re: Simple streetlight hack could protect astronomy from urban light pollution

#134

Post by Anotheroneagain »

cassianoleal wrote: post #54
Anotheroneagain wrote: post #45

Earlier quoted context omitted.

I mean they need to be pretty bright to be visible at all. Notice how red leds still look dim at night, but green blue are shining in the dark room. The eye can't adapt well to dim warm light. And that is the other reason. Those would still make nights look like nights, they should look sort of moonlight like with reasonable brightness.

I'm still unsure what you're advocating for. Dim, but cool coloured lights? That's certainly better than bright cool ones but I still find them very annoying and overstimulating at night. The only thing I can't do with dim, warm lighting is read small text from something other than a backlit screen. For everything else, it's perfectly fine. And if I do see myself having to do that, I'll just add a spot of light to wh…

The problem is that warm lights just look dimmer than they are in reality, you need objectively much brighter warm light to see anything at all. 505nm is a commonly available wavelength that is very near the eye's peak sensitivity in the dark, so a very low powered light would provide sufficient light, and it wouldn't be more overstimulating than moonlight unless it's way too bright. The only drawback it seems to have is that it's rather close to the O-III astronomical filter, I don't know how much it matters.

Re: Simple streetlight hack could protect astronomy from urban light pollution

#135

Post by drpixie »

dahart wrote: post #17
bradley13 wrote: post #5

Right. They're going to get all the streetlights in an entire city to blink in unison. Sure they are. Anyway, in most cases the LEDs don't run at 100%. In our area a, I happen to know that they are between 29% and 40%. That dimming is accomplished by blinking. Which would conflict with the idea of having them blink synchronously. Much simpler solution: ensure the LEDs ghts are directed exclusively downward, and have…

Yes exactly, aim them downward and turn the unused ones off, which is most of them most of the time, and the problem will be solved for everyone. The reason we should do it is that it will save money and power for everyone, the night sky is just icing on the cake. Getting lights to blink in unison is a neat idea, and technically not hard nor too expensive for new lighting. Personally I think the biggest problem with…

Precisely. Why go for the complex, expensive, and fragile solution when better shades (and maybe proximity/motion sensors) would do the job?

Re: Simple streetlight hack could protect astronomy from urban light pollution

#136

Post by BrandoElFollito »

Pedestrian crossings in my city are illuminated by a bright blue light (only the width of the zebra crossing). I did not find that it made me more visible than another color, but obviously, I was not looking at my self from a distance.

is there a reason to prefer these blue lights? (that are a bit uncomfortable for the pedestrian, so there must be a reason)

Re: Simple streetlight hack could protect astronomy from urban light pollution

#137

Post by da768 »

jcalvinowens wrote: post #24
da768 wrote: post #12

Earlier quoted context omitted.

Why not, just sync them to the AC power grid they're all powered from.

Different types of transformers introduce different phase shifts.

Couldn't you still account for offset?

Re: Simple streetlight hack could protect astronomy from urban light pollution

#138

Post by InCityDreams »

AngryData wrote: post #107

How about we just get rid of streetlights. They only make it harder to see everywhere around that isn't directly under a streetlight and are a waste of energy and effort.

I believe several UK cities tried that kind of thing during the last WW. Didn't turn out great for the pedestrians (and also cars had restricted lighting, too). "Put that bloody light out!"

Re: Simple streetlight hack could protect astronomy from urban light pollution

#139

Post by sleepybrett »

mortehu wrote: post #102
sleepybrett wrote: post #93

Earlier quoted context omitted.

because tvs used phosphors it isnt really on/off 50hz just a slight light dip.

If you look at high speed footage of a CRT monitor, you'll see that only a few scan lines are lit at a time. https://www.youtube.com/watch?v=3BJU2drrtCM&t=150s

because of the high framerate you are seeing increased apparent contrast between actively lit and fading phostphors.

Re: Simple streetlight hack could protect astronomy from urban light pollution

#140

Post by giantg2 »

HAMSHAMA wrote: post #67
giantg2 wrote: post #66

Earlier quoted context omitted.

I think that's a bit sexist. While criminals will prey on people they think are weak and that often includes women, that's not exclusively so. I don't know that someone who is vulnerable would really be any safer in a well lit street at night, depending on other circumstances of course. Cars have headlights. It could be that pedestrians can carry lights too. We could reduce infrastructure costs, electricity costs, al…

Maybe, but I have also heard this opinion independently from a few women in my life.

Yeah, I'm simply pointing out that anecdata can contribute to stereotypes. In the way the OP posted it, it sounded like 'men are ok with dark streets, but women are the reason we can't make the streets dark'. When in reality the line isn't on sex but other things like strength and defense knowledge. As I mentioned before, those sorts of things might be more associated with one sex or the other, but it's a mistake to stereotype.
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