25 replies to this topic

[GeorgeLiv]

After more than 45 years of hearing about "increasing" light-pollution (LP) and reading LP related articles, I now find them infuriating and offensive. As devoted amateur astronomers, I think you need to stop posting these LP news items in a forum such as this, especially from the popular media. You're doing a disservice to yourself and to novice astronomers by linking bad science. You will not learn anything new, they oftentimes have dated information, and quite frankly they're often wrong, even those articles written from salaried astronomers.

 

Think about it, if LP has been increasing for that length of time, the stars wouldn't be visible at all. As I've mentioned here https://www.cloudyni...ollution-study/, polluted areas are continuously expanding and the skies seem to be more cloudy/misty to me, but LP is decreasing in many previously polluted areas.

 

I've added some uncalibrated pics here as examples. The topic of what to do to lower LP and curtail its expansion has to start with just the following few paragraphs.

 

Generally, most standard cobra-head street-lights, by virtue of both their design and their wattages, have lower levels of up-light than commercial/industrial/wallpack installations, they always had.

 

 

A good full-cutoff LED fixture installation today contributes to LP only by reflected light. Without an obstructing canopy, this can be as low as 4% of the lamp light (all grass underneath) to a high of 25% (newer concrete). Up-light percentages are typically lower with foliage canopies. Most other lights, such as private billboard lighting, flood-lighting and some lot lighting have direct up-light. Their watts are also huge, they always were.

 

 

Of course there were public installations that were more polluting, however, these were often, if not always, non-standard fixtures such as post-tops or ornamentals. Most of these bad polluters have been replaced with better LED ornamental fixtures.

 

 

The contribution to up-light from the aforementioned commercial/industrial/wallpack fixtures is still enormous. It always was. Over 25 years ago, in the early to mid sodium era, finding scandium emission lines in the spectrum of my sky-glow indicated to me that commercial areas contributed significantly to the then LP. Scandium is only added to metal-halide lamps. As I see it and I'm able to estimate, the contribution from LED commercial/industrial/wallpack installations today is over 80% of sky-glow.

 

 

There will be some LED street-lights brighter than commercial/industrial/wallpack installations, but these full-cutoff lights are few (boulevards or major collector roads) and not as widespread as all the residential street-lights. As far as we're concerned, it is far better to generalize in order to move on and fix the real problem of LP. I think it's imperative. Keep off the street-lights, they're almost perfect! Tackle the unregulated private lot, architectural and billboards and you should have a clear-cut reduction in LP.

[Supernova74]

light pollution is always going to be around unfortunately unless the government or local authorities here! in the uk anyway change there thinking strategy.however what’s the point in having certain unwanted light pollution shooting upwards into the atmosphere which I consider wasted energy anyway and the on going cost of energy prices if it’s government related or more domestic.if these light sources actually had a beam of light which mainly concentrated downwards not only us amateur Astronomers genrally would be more happy in being able see more of the night sky I’m also certain energy costs could be reduced also with new lighting technology.

 

On the plus side there are certain locations in the uk that monitor unwanted light pollution which seems to be mainly in protected dark sky sites when wardens of some description give you a telling off if unwanted artificial light sources prove to be to much and completely unnecessary.i personally feel tho we all need to change our habits into more positive cost saving solutions and not just for unwanted artificial light pollution that us amateur Astronomers all hate as this can also cause health related issues in humans and nocturnal animals behaving oddly and also seem to suffer the consequences.

[TOMDEY]

Sharing information... even questionable or misleading information --- is a good thing! Let the reader decide what to believe and what to not. The more inputs, the better.

 

PS: I was a lighting designer decades ago. Especially the good ones, like Low Pressure Sodium (my patents), which is monochromatic and entirely filterable! But people don't like the color. They want bright white light. It's hopeless. Here's an old picture from one of my consulting/collaborating trips out to KPNO, etc.   Tom

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[Supernova74]

Then again you simply don’t have to read the articles and get dragged into reading those tabloids there’s always a choice.

[Tony Flanders]

After more than 45 years of hearing about "increasing" light-pollution (LP) and reading LP related articles, I now find them infuriating and offensive. As devoted amateur astronomers, I think you need to stop posting these LP news items in a forum such as this, especially from the popular media. You're doing a disservice to yourself and to novice astronomers by linking bad science. You will not learn anything new, they oftentimes have dated information, and quite frankly they're often wrong, even those articles written from salaried astronomers.

 
Two important studies of light pollution have been published in the last month. You appear to be under the impression that these articles claim that LED street lights are a bad thing. In fact neither article says a word about LED street lights. It makes no difference to the arguments, methodologies, or conclusions of the articles whether the sources of the light pollution are due to street lights, commercial lighting, or any other form of lighting. I have some questions and doubts about both articles' conclusions, but neither can be called "bad science" by any reasonable person who has actually read the articles, and neither uses dated information.

 

The first article, by the team responsible for the most widely used light-pollution map, applied the methods behind that map to study a few specific locations intensively, as opposed to the map, which supplies a single datum (estimated zenithal light pollution) for every location on Earth. The locations in question include all the world's major observatories, a number of historically important observatories, and a few amateur sites.

 

Unfortunately the full text of the article now requires privileged access, but you can read the abstract here. The conclusion of the article is that whereas most major observatories skies are still only marginally affected by light pollution at the zenith, they do have a problem 30 degrees above the horizon where (the article estimates) light pollution typically averages 3 to 6 times stronger than at the zenith.

 

The second article, in Science, is still available in full. It summarizes some findings of the Globe at Night project, which has been collecting NELM estimates for more than a decade. I will quote from the abstract, which is very carefully worded:

 

 

The number of visible stars decreased by an amount that can be explained by an increase in sky brightness of 7 to 10% per year in the human visible band. This increase is faster than emissions changes indicated by satellite observations. We ascribe this difference to spectral changes in light emission and to the average angle of light emissions.

 

If you look at their data, the decrease in NELM is quite dramatic -- too big for me to think that it's caused by random variation or a flaw in methodology. And it is indeed the same decrease that would be expected if skyglow has increased 7% to 10% annually. Personally, I don't think the decrease in NELM is caused primarily by an increase in skyglow, but it is consistent with a large increase in skyglow, which is all the article is really claiming.

Edited by Tony Flanders, 22 January 2023 - 08:07 PM.

[GeorgeLiv]

I'm just going to quickly reply and suggest that perhaps NELM (naked-eye limiting magnitude) is not an end-all indicator for night-sky brightness. I need to mention that I've been photographing unusual and faint air-glow activity from my isolated cabin. In fact, most of the last two years (2021 & 2022) have been very bright - but still near 21.82 mags/arcsec² (mpass). Important to note that I never recorded 22.00 mpass, so something is happening.

 

If the study period ranged from 2011 to 2022, one can easily make the inference that LED conversations, which occurred universally in North America during that period, are responsible for the apparent increase. I am also going to add that an increase in sky brightness is a natural result of changing en-mass outdoor lighting. It will get darker after a burn-in period, just like it did prior to scrapping HPS lighting, say about 2005-2011. The Science article reminds me of the alarming and pessimistic period of the late 80s and early 90s. That's when HPS came along for virtually all outdoor lighting. Remember that period?

 

When I get the time I'll be posting some before & after digital images, comparing the illumination by exploiting the EXIF data. So yeah, not manipulated like in many of the images in those articles.

Edited by GeorgeLiv, 22 January 2023 - 10:22 PM.

[Jon Isaacs]

George:

 

So.. I was born in 1948. The population of San Diego county was 550,000 people. Today. It's 3 million. Do you believe that was accomplished without an increase in light pollution?

 

Jon

[Tony Flanders]

If the study period ranged from 2011 to 2022, one can easily make the inference that LED conversations, which occurred universally in North America during that period, are responsible for the apparent increase. I am also going to add that an increase in sky brightness is a natural result of changing en-mass outdoor lighting. It will get darker after a burn-in period ...

Your point about lamps getting dimmer over time is a good one; I hadn't thought of before.

For what it's worth, satellite data actually show a significant decrease in uplight during that time period in North America and a smaller one in Europe. The overall 2% annual increase detected by the satellites is due almost entirely to the under-industrialized world.

 

This data backs up your point about LED luminaires generally having less spilled light. However, this does appear somewhat contradictory to the claim in your initial posting that 80% of uplight is due to commercial installations. If only 20% of skyglow was ever due to streetlights in the first place, how could replacement with LED streetlights yield significant decreases?

 

Of course the satellite data is problematic because all a satellite can detect is uplight and light reflecting off the ground. The most harmful light as far as skyglow is concerned is not the light that shines down and helps people, nor the light that shines up into outer space and is readily detected by satellites, but rather the light that shines almost horizontally, scattering light down to the ground until it's cut off by Earth's curvature.

[pstarr]

I find that homeowners in my area have discovered the bright white LED lights for outdoor use. Where I live, the once incandescent garage and porch lights have been replaced with lighting that is many times brighter than to old lights. The lights are not shielded at all. I'm pretty sure this is going on everywhere right now. It has significantly increased the sky glow in my once fairly dark rural area. Just a quick look at a house actress the street takes care of any dark adoption I might have had. Businesses are doing the same thing. More light for less cost is the trend and it's catching on.

Edited by pstarr, 23 January 2023 - 09:48 AM.

[gene 4181]

  People don't understand the difference in output and  color  that  these new LEDs bring.    Go ahead and explain it to them and  that you're an active astronomer,  LIGHTS ON!   I even let them look thru my 10 inch dob , they'll get it ! NOPE !  LIGHTS ON!   And those Dollar General  Bell and Howell 10,000 LED Solar powered security lights , what are they afraid of  ?    Thank you , I have a little red light ! Bunch of Nancy Graces, its dark and what is that he's doing? Must be evil , its dark out .     You can't fix stupid .   

[GeorgeLiv]

A few more very quick replies..

 

@gene 4181 - No of course you can't fix stupid, but you can regulate it.

 

@pstarr - Truly rural areas, those at least an hour's drive from a sizable town, are most affected by low powered outdoor porch lights. Still, the sky-glow from distant towns with any amount of commercial lighting overpowers the effect that porch lights have on these dark places

 

@Tony Flanders - The "increases" that I clearly see, and I would clarify these as an "amplification" in LP, are over the commercial routes and centers as well as many industrial sectors. I believe this is due to the enormous output of the new & unregulated installations, not their full-cutoff designs (and wallpacks have always been polluting, still are). In residential sectors, a lot of the lighting on ground has stayed about the same, but the up-light from these sectors (no wallpacks here) has dropped.

 

We know that LP is "expanding" outwards into the countryside around urban centers. The amplification in LP here is not because of the new residential homes and their streets, but due to the main routes receiving the necessary support, such as gas stations & strip malls. In my opinion, the disparity between the two types of sectors - residential vs commercial - has grown significantly w/LED, so that over 80% of North American town or city sky-glow is due to commercial centers but including industrial zones (those blasted wallpacks!).

 

I agree that the developing nations (or underdeveloped regions) are losing their dark skies. This isn't a real surprise since solar powered LED systems can easily be installed by the most isolated community. Spotting 7th magnitude stars have no chance in being seen here as well.

 

@Jon Isaacs - The San Diego region has always been a special LP case from before the 1980s. This is due to nearby Palomar Observatory which housed the famed 200 inch Hale telescope. Palomar directors had been voicing their concerns for a long time and city officials were persuaded to opt for the high efficacy and monochromatic light of LPS/SOX lighting inside full-cutoff fixtures. In 1983 the city was among the first area in the world adopting any full-cutoff lights.

 

Disliking the monochromatic lights, in the late 1990s the city endorsed a program to replace two-thirds of its street-lights to HPS, mostly in full-cutoff designs. Beginning in 2010, San Diego switched 5,700 street-lights to fluorescent induction-lighting. In 2018, the city installed 3,000 advanced LED systems. I'm not sure what they ended up with now. Have all the induction lighting fixtures been scrapped? 

[Jon Isaacs]

 

@Jon Isaacs - The San Diego region has always been a special LP case from before the 1980s. This is due to nearby Palomar Observatory which housed the famed 200 inch Hale telescope. Palomar directors had been voicing their concerns for a long time and city officials were persuaded to opt for the high efficacy and monochromatic light of LPS/SOX lighting inside full-cutoff fixtures. In 1983 the city was among the first area in the world adopting any full-cutoff lights.

 

 

Disliking the monochromatic lights, in the late 1990s the city endorsed a program to replace two-thirds of its street-lights to HPS, mostly in full-cutoff designs. Beginning in 2010, San Diego switched 5,700 street-lights to fluorescent induction-lighting. In 2018, the city installed 3,000 advanced LED systems. I'm not sure what they ended up with now. Have all the induction lighting fixtures been scrapped? 

 

I first visited the 200 inch 70 years ago at age 5. 

 

My point is that historically, light pollution has grown with population growth. Regardless of attempts by San Diego to hold light pollution in check, the population has grown immensely as has light pollution.

 

Cities like Escondido, Temecula, Murrieta, which are all within 25 miles of the observatory, were small towns in 1953, maybe 5000. Today, they're 120,000 to 150,000 people, each.

 

Reality in not doom and gloom.

 

Jon

[GeorgeLiv]

Cities like Escondido, Temecula, Murrieta, which are all within 25 miles of the observatory, were small towns in 1953, maybe 5000. Today, they're 120,000 to 150,000 people, each.

 

Reality in not doom and gloom.

 

Jon

The cities you mention, including San Marcos, Poway & Hemet, were still required to use low-pressure sodium in full-cutoff heads up until very recently. I'm not sure what type (LED? Induction?) or Kelvin temperature heads they currently use.

 

But look here: https://www.ebay.com/itm/144522119781 ..a scrapper in the area is selling Spaulding Palomars once used in Escondido at reasonable prices. Also https://www.ebay.com/itm/144529893451
 

And I have no argument against doom/gloom population growth. This is natural & expected. And I DON'T mind sprawling residential areas. I mind the commercial zones accompanying them.

Edited by GeorgeLiv, 23 January 2023 - 11:27 PM.

[jcj380]

I find that homeowners in my area have discovered the bright white LED lights for outdoor use. Where I live, the once incandescent garage and porch lights have been replaced with lighting that is many times brighter than to old lights. The lights are not shielded at all. I'm pretty sure this is going on everywhere right now. 

And the clowns here are stringing LED "party lights" all over their decks / patios that they leave on all night even through the winter.  It's a rare sight to see people outside here even when the weather is nice - maybe they're all watching Netflix - which makes me wonder what they're hoping to achieve.

[Jon Isaacs]

The cities you mention, including San Marcos, Poway & Hemet, were still required to use low-pressure sodium in full-cutoff heads up until very recently. I'm not sure what type (LED? Induction?) or Kelvin temperature heads they currently use.

 

But look here: https://www.ebay.com/itm/144522119781 ..a scrapper in the area is selling Spaulding Palomars once used in Escondido at reasonable prices. Also https://www.ebay.com/itm/144529893451
 

And I have no argument against doom/gloom population growth. This is natural & expected. And I DON'T mind sprawling residential areas. I mind the commercial zones accompanying them.

 

More people = more light. 

 

I've lived in San Diego county my entire life. Lighting ordinances are great but they're a drop in the bucket when a town of 6000 becomes a town of 150,000.. In 1950, the Temecula-Murrieta region had a population of 9000. Today it's 965,000.

 

https://www.macrotre...eta/population 

 

Jon

[GeorgeLiv]

So what type of street-lights, like in San Diego, do these towns currently have (for 2021-2023)?

 

Please don't go off-topic with population demographics, but info on what these peeps employ is appropriate & appreciated.

[pstarr]

Earlier in this thread (post #9) I had mentioned how people were lighting up their houses with the new bright unshielded LED lights. This house is across the street from me and is typical of what I'm seeing. You can see on the snow that they light up the yard I'm standing in too. I didn't realize that people were standing outside smoking until I got back in the house and looked at the picture. Looks like the guy in the doorway is watching me take it. By the way, those lights are on all night. The lights look much brighter it the photo before I had to reduce the size for posting it on here.

Edited by pstarr, 25 January 2023 - 08:24 AM.

[Illinois]

Earlier in this thread (post #6) I had mentioned how people were lighting up their houses with the new bright unshielded LED lights. This house is across the street from me and is typical of what I'm seeing. You can see on the snow that they light up the yard I'm standing in too. I didn't realize that people were standing outside smoking until I got back in the house and looked at the picture. Looks like the guy in the doorway is watching me take it. By the way, those lights are on all night. The lights look much brighter it the photo before I had to reduce the size for posting it on here.

IMG_0192.jpeg

WOW! That is  (beep) up!  he pay lot of money on waste and unwise lights! 

[Jon Isaacs]

So what type of street-lights, like in San Diego, do these towns currently have (for 2021-2023)?

 

Please don't go off-topic with population demographics, but info on what these peeps employ is appropriate & appreciated.

 

If you think population figures are irrelevant to understanding light pollution increases, I will refrain from any further discussions.

 

But compared to population dynamics, street lighting is insignificant...

 

Jon 

[Neanderthal]

I don't know what's going on in Canada, but everything I see now days is very typical of the photo in post #17. It's all LED or bust. Most folks can't have enough outside lighting and dark skies aren't even an afterthought for those that don't own & use a telescope. More people = more light, just the way it is.

[Fredb76]

LED light is very energy efficient, so many people leave it on all the time.

[GeorgeLiv]

The house on the left is lit quite reasonably. The house on the right is a nuisance; I wouldn't setup my observing facing that house.

 

Back on topic,.. in my opinion, as I see it, the recent brightening of the night sky is due to..

 

1 - a natural increase in air-glow from a dramatic up-tick in solar activity;

 

2 - an increase in upper level air temperatures & thin cloud-cover, possibly due to a resumption of normal air traffic;

 

3 - an increase in stratospheric particles from space-x flights, forest fires & volcanic ash.

 

I don't think it's from LED lighting, but cloud/mist in upper air may be reflecting it. I remember in 1992 when night skies were literally silver in the wake of mount Pinatubo (in the Philippines) erupting.

 

Surrounding my country place, most conversions to LED occurred from 2015 to 2017. I saw small drop in sky-glow of about 0.2 mag, which really was an enormous increase in my naked-eye limiting magnitude (NELM) from about 6.3 to 6.5 magnitudes. I could get some times 22.05 mags/arcsec² and was able to spot M33 (Triangulum galaxy) with direct vision. In 2021 I lost that gain. 2022 was awfully bright, never being able to easily spot M33 even by averted vision. Photographed lots of red air-glows, & unusual red clouds not easily seen with dark-adapted eyes, so something is for sure happening.

[Augustus]

Would be interesting to see what results would come if maybe 10% of the effort put into these arguments went into writing letters, handing out brochures, or other easily-achievable measures to actually do something about LP. The worst part of the "doom and gloom" isn't even the attitude IMHO, it's the fact that the work put into basically just being discouraging for the sake of it could've gone into useful action to mitigate the problem

Edited by Augustus, 27 January 2023 - 03:29 PM.

[Augustus]

If you think population figures are irrelevant to understanding light pollution increases, I will refrain from any further discussions.

 

But compared to population dynamics, street lighting is insignificant...

 

Jon 

We have 1 million people in the Tucson metro area. Bortle 2-3 is still within an hour of the city center in basically all directions and our ordinances aren't even that well-enforced right now.

[GeorgeLiv]

These replies are easy to compose, write and edit. Finding the the right person to contact with any pertinent info is difficult to begin with. If this person is preoccupied with their title (physicist, pro astronomer, politician, civil servant) they simply don't read, care, or have the desire to pay attention especially to information coming from a lay person such as myself. I'm just a photographer.

 

Like any other city of one million people, an hour's drive from the city center should yield a NELM of at least 6.0 mag. Tuscon Arizona is nothing special, except for the climate.