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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

#41

Post by qmarchi »

canoebuilder wrote: post #31
fragmede wrote: post #29

Earlier quoted context omitted.

Cheaper to operate, which over an entire city's worth of street lamps is very material. Sodium-vapor lights eventually need to be replaced (as do LEDs), so why not replace them with a modern technology that's cheaper to operate?

> Cheaper to operate I’ve seen in a number of places where the led lights have rapidly degraded, putting out really unpleasant bluish, purplish hues, as if the super bright daytime like sports field lighting everywhere wasn’t already bad enough. So this rapid degradation necessitating replacement no doubt eats into some of the cost savings. Also, “cheaper to operate” mostly seems to have turned into “pump out more ph…

There was some historical reporting where lights were delaminating because of a bad batch of panels produced by Acuity. It's not representative of the majority of LED installations, but each install may vary.

https://fee.org/articles/why-are-some-us-street-lights-turni...

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

#42

Post by coryrc »

galdosdi wrote: post #10
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…

I'm not sure I'd be so quick to dismiss the feasability, at least not based on your reasoning so far. FM Radio stations have managed to accomplish getting the speaker in your car radio to "blink synchronously" according to a complex signal pattern in the exact same way as millions of other radios simultaneously.... for about a century now. As long as all streetlights are in locations with good radio reception (which,…

You must not be familiar with multipath interference. Radio isn't quite as synchronous as you believe it to be.

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

#43

Post by dreamlayers »

I think a big part of the problem is use of cool white LED lights, which produce more light on the blue part of the spectrum. That light scatters more in the atmosphere, like how the sky is blue during the day.

Around here, the LED lights do not seem brighter like the article claims.

Also, they are all full cutoff. In the past, almost all high pressure sodium streetlights meant to send light downwards had a glass globe below, which sent some light upwards. LED streetlights have flat panels instead, so none of the light fixture itself can directly send light into the sky. Only light reflected from illuminated objects and scattered by the air can light up the sky.

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

#44

Post by canoebuilder »

cassianoleal wrote: post #38
Anotheroneagain wrote: post #34

Earlier quoted context omitted.

You could see the attackers just as well as they see you. I meant because of the annoyance that it would create. The problem with warm lights is that they are much harder to see in the dark. Maybe dim lights around 505nm would be a better idea.

> You could see the attackers just as well as they see you. That's only if they're moving within the sensors that switch on the light. > The problem with warm lights is that they are much harder to see in the dark. Not sure what "in the dark" means here. Light by definition is easier to see in the dark than it is in light as it has less light to compete with. In any case, I find warm lights much easier. Cold lights a…

>If you need more light clarity, light your own phone torch or something.

Good point! In this case of nighttime lighting infrastructure it has become so vastly overbuilt as if to save people “the trouble” of these simple targeted solutions.

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

#45

Post by Anotheroneagain »

cassianoleal wrote: post #38
Anotheroneagain wrote: post #34

Earlier quoted context omitted.

You could see the attackers just as well as they see you. I meant because of the annoyance that it would create. The problem with warm lights is that they are much harder to see in the dark. Maybe dim lights around 505nm would be a better idea.

> You could see the attackers just as well as they see you. That's only if they're moving within the sensors that switch on the light. > The problem with warm lights is that they are much harder to see in the dark. Not sure what "in the dark" means here. Light by definition is easier to see in the dark than it is in light as it has less light to compete with. In any case, I find warm lights much easier. Cold lights a…

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.

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

#46

Post by canoebuilder »

cassianoleal wrote: post #39
canoebuilder wrote: post #30

Earlier quoted context omitted.

Last sentence is a fine idea, it is also possible to move toward developing a society where “potential attackers” is a thought much more distant in people’s minds.

> it is also possible to move toward developing a society where “potential attackers” is a thought much more distant in people’s minds Amen, but alas we're not there. In any case, threats don't always come from purposeful attackers. It's useful to see animals, vehicles and bikes with no light, etc.

>Amen, but alas we’re not there

What is troublesome is that many places, that many of us probably hail from, “were there” not so long ago, and it was destroyed by duplicitous, malicious political and cultural actors.

Having “safe streets” is not a pipe dream. Indeed not having them is a symptom of people trying to destroy our societies.

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

#48

Post by saltcured »

coryrc wrote: post #42
galdosdi wrote: post #10

Earlier quoted context omitted.

I'm not sure I'd be so quick to dismiss the feasability, at least not based on your reasoning so far. FM Radio stations have managed to accomplish getting the speaker in your car radio to "blink synchronously" according to a complex signal pattern in the exact same way as millions of other radios simultaneously.... for about a century now. As long as all streetlights are in locations with good radio reception (which,…

You must not be familiar with multipath interference. Radio isn't quite as synchronous as you believe it to be.

And of course the light itself is also undergoing multipath distortions like the radio signal. And for astronomy, the changing atmosphere might be the most important secondary reflection. And the multipath arrangement between emitter and observer is different for each pair.

Could you make a dark period long enough to mask the multipath variance among emitters and observers? Or would this dark period be so long as to cause annoying flicker?

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

#49

Post by Evidlo »

galdosdi wrote: post #10
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…

I'm not sure I'd be so quick to dismiss the feasability, at least not based on your reasoning so far. FM Radio stations have managed to accomplish getting the speaker in your car radio to "blink synchronously" according to a complex signal pattern in the exact same way as millions of other radios simultaneously.... for about a century now. As long as all streetlights are in locations with good radio reception (which,…

Wavelength of FM radio is about 3m, so you only have to be a few centimeters shifted to be seeing an entirely different phase and be out of sync.

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

#50

Post by nativeit »

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.
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