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Comment by tut-urut-utut | Hacker News Reader

It's not like nothing can be done about light pollution. For example Germany has a law about light pollution, and it shows on this map. It less polluted than its neighbours, although it has higher population density and urbanization level.

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Lord knows if I were emperor or whatever, I would have some fairly draconian laws on the books, with hefty fines, about so many light sources. I can walk around at night and read a paper books. It's easy. Some places, I feel like the going standard is "can someone perform open heart surgery on this stretch of road?"

A lot of it is a race to the bottom -- look at my sign! Sure, my business is not open right now, but I have a sign! Advertising alone is a huge detriment to the light pollution landscape.

Much of it comes from misguided "this will be safer" concerns. And so half the neighborhood has these floodlights installed above their doors that will be on all night, plus little solar lights everywhere. Oftentimes, they're positioned so poorly that it actually makes seeing people walking around more difficult, due to having these things shine away in my eyes.

One of my particularly patriotic neighbors has a big US flag atop a pole in his front yard. And he's following flag code, making sure that since he leaves it up at night it is properly lit. With a couple great big floodlights aimed straight up at it from the ground.

I was driving down the highway at night a few years ago, before digital billboards were as common here. I saw one with a dark background that I was struggling to read, but then it transitioned to a different ad with a bright white background.

Instantly blinded. I was fortunate there weren’t a lot of cars around, because it took a few seconds to be able to see clearly again.

I don't understand how digital billboards are legal. They're way too bright for night driving.

Tucson, Arizona has laws to limit light pollution out of consideration for the nearby observatories. I remember bicycling along roads and the lights turning off intermittently. Great to be able to see the stars at night, though; I’d much rather that than lighting all the things.

https://www.lightpollutionmap.info/#zoom=7.00&lat=34.1123&lo...

Flagstaff vs. Prescott in Arizona is another good example. Flagstaff has strict output per area limits, Prescott has none, while the density of both areas is similar.

Flagstaff makes an effort to enforce their lighting ordinances, Prescott makes no effort whatsoever.

I think the problem is that all the people who knew why the lighting ordinances were passed retired. Because Prescott doesn’t have Lowell Observatory in the city limits the reasons behind the ordinances were forgotten.

Blue-white outdoor lighting should be prosecuted as a public nuisance.

Astronomy isn't the only reason though. It affects wildlife pretty badly too.

Cave Creek Arizona is another dark sky area (where we live) and it's an excellent thing

The International Dark Sky Association has some template laws that can be used as a starting point:

> The MLO offers several innovations to outdoor lighting regulation, including the use of lighting zones to classify land use with appropriate lighting levels for each. The MLO also makes use of the “BUG” (Backlight, Uplight and Glare) classification of outdoor lighting fixtures to ensure that only well-shielded fixtures are used.

* https://www.darksky.org/our-work/lighting/public-policy/mode...

Germany doesn't seem appreciably better than France, looking at the map.

Peak levels are the same for Berlin as for Paris. The width of Paris's light pollution is wider, but it's also double the population of the metropolitan area.

And actually, rural areas of Germany seem consistently and significantly brighter (worse) than rural areas in France, across both countries.

Is there really a lot that can be done about light pollution? Isn't it mostly due to streetlights, which you want on for safety?

I mean, sure there are some metropolitan downtown areas with bright lighting of advertising, but that's very localized.

Is there really low-hanging fruit that cut could overall light pollution by, say, 50%, without impacting safety?

What is the law? What are people legally required to do?

Probably the most noticable change in recent years is the replacement of mercury-vapor streetlights with the yellow-orange sodium-vapor lights, or with orangish LEDs (although some use blueish LEDs that are not that great for light pollution).

In terms of actual legal requirements, Bavaria prohibits sky beams/searchlights directed upwards, and the illumination of facades of public buildings between 11pm and morning.

While switching to LEDs can improve naked eye view of night sky, it sometimes negatively impact amateur astrophotography as mercury and especially sodium lamps have narrow emission spectrum and it can be filtered off using optical bandpass filters. LEDs light have much wider spectrum and cannot be filtered off.

San Jose, California does this for the Lick Observatory at Mt. Hamilton, although I think they're switching to blueish LEDs. The sodium-vapor lights are frequently mistaken as yellow traffic lights though, in my experience.

yellow-orange sodium-vapor lights are terrible for anyone who's not an astronomer. The sharp output spectrum prevents humans from seeing color

Do you really need color vision in the middle of the night?

Even with wide spectrum lights, turning them down is going to suppress colors anyway.

Actually, I stand corrected, there's no federal German law about light pollution. It's left to different federal states, and most of them incorporated regulations about light in their legislation.

I can't find an English text but the document from the federal parliament below summarizes the legal state of the topic in Germany.

https://www.bundestag.de/resource/blob/632966/7ba7c4cd1cfef8...

Most light pollution laws limit outdoor lighting fixtures and require them to only emit downwards and not upwards.

I would vote for anyone who would even talk about light pollution as a serious issue. All my friends (rightly) think I am a wacko because I advocate the removal of all streetlights and regulation of private outdoor lights.

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