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LEDs’ potential to save our night skies

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Re: LEDs’ potential to save our night skies

#101

Post by NoMoreNicksLeft »

SoftTalker wrote: post #97
uv-depression wrote: post #25

Greenhouses here in the lower mainland of British Columbia have been devastating to the night sky. It's quite depressing how little society values the night sky, something that's been an important part of every human culture for longer than recorded history. I've taken friends out to thoroughly mediocre skies (Bortle 4-5) and they've been very impressed, because they're used to city lights (Bortle 9) where you can ma…

I would have assumed that most plants need a daily light/dark cycle but maybe not?

The world record holder vegetables are all grown in Alaskan summers, up north... where they get 20+ hours of daylight per day. Dunno, maybe the CAM plants would do bad (pineapples) but just about everything else benefits.

Re: LEDs’ potential to save our night skies

#102

Post by uv-depression »

qurren wrote: post #99
uv-depression wrote: post #25

Greenhouses here in the lower mainland of British Columbia have been devastating to the night sky. It's quite depressing how little society values the night sky, something that's been an important part of every human culture for longer than recorded history. I've taken friends out to thoroughly mediocre skies (Bortle 4-5) and they've been very impressed, because they're used to city lights (Bortle 9) where you can ma…

Starlink gets a lot of flax for it but as an avid night sky photographer myself (IG: @dheeranet) who regularly goes to Bortle 1 parts of the world, I haven't found them to be an issue at all. 1. They are only visible when they are spinning up to orbit 2. They are too dim to desensitize your eyes, and are extremely easy to remove with the most basic of outlier rejection techniques; netizens often amplifiy outliers by…

(1) Considering there are now multiple companies planning to launch their own fleets of tens of thousands, satellites need replacing, etc, even if this was completely accurate, this will be a continuous and ongoing issue as it has been for years.

(2) The standards for astrophotography and for professional astronomical measurements are somewhat different! Also, I think you meant median stacking; mean stacking doesn't handle outliers as well.

(3) Whataboutism. Besides, you'd get no argument from me about replacing the majority of air travel with high speed rail, even without considering lights.

I agree that city light pollution is probably the bigger problem, especially for the amateur/cultural angle, but these are two symptoms of the general cause of our economic system not valuing the sky (or the environment generally).

Re: LEDs’ potential to save our night skies

#103

Post by trollbridge »

dec0dedab0de wrote: post #27
trollbridge wrote: post #21

Earlier quoted context omitted.

In the U.S., the DOT sets standards, but they only apply to new vehicles sold. Aftermarket lights can be just about anything. (Some are labelled "not for highway use", as if that prevents them from being used on public roadways.) Certain types of people seem to think they should install really, really bright LED lights in their car and then aim them right at other driver's eyes. I believe this comes from a mindset wh…

I hated these so much until I got a car with a tinted rear windshield, and a self-dimming mirror.

Or get the orange driving glasses.

Re: LEDs’ potential to save our night skies

#104

Post by tredre3 »

SoftTalker wrote: post #97
uv-depression wrote: post #25

Greenhouses here in the lower mainland of British Columbia have been devastating to the night sky. It's quite depressing how little society values the night sky, something that's been an important part of every human culture for longer than recorded history. I've taken friends out to thoroughly mediocre skies (Bortle 4-5) and they've been very impressed, because they're used to city lights (Bortle 9) where you can ma…

I would have assumed that most plants need a daily light/dark cycle but maybe not?

Most fruit crops need 8-12 hours of darkness but it changes depending on which point they're at in their life cycle. 20 hours of light is usually fine during the initial stages, then they require 8-10 hours of darkness to bloom, then back to 18-20 hours of light during the fruit growth.

(I'm not a botanist or a farmer but I grow greenhouse veggies for fun)

Re: LEDs’ potential to save our night skies

#105

Post by qurren »

uv-depression wrote: post #102
qurren wrote: post #99

Earlier quoted context omitted.

Starlink gets a lot of flax for it but as an avid night sky photographer myself (IG: @dheeranet) who regularly goes to Bortle 1 parts of the world, I haven't found them to be an issue at all. 1. They are only visible when they are spinning up to orbit 2. They are too dim to desensitize your eyes, and are extremely easy to remove with the most basic of outlier rejection techniques; netizens often amplifiy outliers by…

(1) Considering there are now multiple companies planning to launch their own fleets of tens of thousands, satellites need replacing, etc, even if this was completely accurate, this will be a continuous and ongoing issue as it has been for years. (2) The standards for astrophotography and for professional astronomical measurements are somewhat different! Also, I think you meant median stacking; mean stacking doesn't…

Some good points. However:

> replacing the majority of air travel with high speed rail

I absolutely LOVE high speed rail, but I will note that it is correlated with far more light pollution than air traffic. I say correlated because typically high speed rail is routed through high-density population centers, but if there aren't population centers, you'll have to have plans to create them in order to support the rail system itself.

Basically there is nowhere in the world that has both high speed rail AND suitable for astronomy. If you want to find dark skies in China for example you have to get far away from all the high speed rail areas of the country.

Re: LEDs’ potential to save our night skies

#106

Post by matkoniecz »

uv-depression wrote: post #25

Greenhouses here in the lower mainland of British Columbia have been devastating to the night sky. It's quite depressing how little society values the night sky, something that's been an important part of every human culture for longer than recorded history. I've taken friends out to thoroughly mediocre skies (Bortle 4-5) and they've been very impressed, because they're used to city lights (Bortle 9) where you can ma…

> instead of building municipal internet

Starlink is intended and used as solution for places and uses for which municipal internet is not an option at all

(is it usable at all as replacement for municipal internet? I would guess that you would overcrowd connection quite quickly)

Re: LEDs’ potential to save our night skies

#107

Post by tredre3 »

miladyincontrol wrote: post #96

I think people focus far too much on the temperature of LED street lights and rarely on the CRI. The night will still feel odd and "soulless" even with 2700k LED street lamps so long as they're still the absolute worst CRI. Dare I argue even I would choose 6500k LED street lights with decent CRI over poor CRI 2700K LED lamps any day.

> The night will still feel odd and "soulless" even with 2700k LED street lamps so long as they're still the absolute worst CRI.

What makes you say that the CRI causes the lack of soul? I'm not saying that you're wrong, but given that CRI is objectively better than it ever was now, why?

The sodium lamps we used previously had a CRI of 25-35. The absolute worst white LEDs we have have a CRI of at least 60.

Re: LEDs’ potential to save our night skies

#108

Post by tredre3 »

weberer wrote: post #40
Rotundo wrote: post #23

Earlier quoted context omitted.

Using PWM to dim lights should be banned wholesale. Many people, me included, get crazy headaches from the worst lights and mild discomfort from the best ones. It's also completely unnecessary as non-flickering bulbs do exist and are readily available for the same price.

Those are probably 50-60 hz flickering from the mains frequency rather than PWM. (Or 100-120 hz due to the rectifier). Actual PWM ICs drive LEDs over 10,000 hz, which is truly imperceptible to the human eye.

Surely a PWM of 10,000Hz wouldn't allow for night sky photography. With full exposure it can already take minutes of hours to take a night sky a photo.

And it's usually recognized that 1,000hz is the bare minimum to spare sensitive individuals from symptoms, with 2,500 usually used for safety margin. Then you have to account for some jitter in the synchronized network so you're looking at at best a 1/5,000 exposure.

Is that sufficient to be worth the trouble?

Re: LEDs’ potential to save our night skies

#109

Post by apparent »

> The use of solid-state technology gives the lights an extraordinary life-span, often measured in decades rather than years.

I have found this not to be the case. They seem to last several years, but not an amazing period of time. Also, the ones that were installed in my home are quite expensive, something like $45 per can (the whole thing must be replaced), and the price to install is $30 per can because the company changed their plug design in the last 5 years. So I end up spending $75 for each light, which is roughly $10 per year per light (per light-year?). That doesn't strike me as a great value, especially because I can't change the lights myself due to the wiring/plug situation. Maybe that piece won't apply in future years, but it's still a lot even if it's just $45 for the darn can.

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