LEDs’ potential to save our night skies

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 maybe see a few of the brightest stars and planets.

If you've never seen truly dark skies, do yourself a favour and go see what they look like during true night. Bring binoculars if you have them, maybe get a planisphere and a (dim!) red flashlight.

The lack of respect for the night sky includes starlink and the other internet providers dumping tens of thousands of satellites in orbit instead of building municipal internet, by the way. It's been a huge hit to the field of astronomy. Before someone inevitably says "we should just be putting telescopes in orbit", orbital observatories are obviously a huge deal and I support building more of them, but you simply can't put things like the ELT (40m primary mirror, 2800 tonnes) or the Square Kilometre Array in space.

> “… gives the illusion, without the reality, of safety”

This actually isn’t true. Having done physical security work before, a weird fact is that one of the best physical deterrents is lighting; even over CCTV.

I don’t say that to take away from this, this is great work and I’d love to see the lighting toned down for multiple reasons. However, this should be framed as a security tradeoff not an outright win.

Source: The Impact and Policy Relevance of Street Lighting for Crime Prevention: A Systematic Review Based on a Half-Century of Evaluation Research (https://www.crimrxiv.com/pub/wl9zqxga/release/1)

Where I live, we have a small park, 500m away. You need to walk through it if you want to get to the city center from the small neighborhood we live in. To protect the wildlife, the lighting system has presence sensors, so as you walk or bicycle through the park, the way/street lighting turns on, you can walk, and just after you, it turns dark again. Really cool, especially the first time I went through it in the middle of the night.

We need much better engineering standards if we are going to fix night lighting. A simplistic lux-on-the-ground measure combined with cost minimization produces a few lights, with bare bulbs, up hight, with brutal intensity. These are all things that produce glare directly on the eyeball.

You need much less light on the ground if the eyeball itself has no direct line to the hottest part of the lights. Instead, the night-blindness caused by excessive bare lighting is "fixed" by adding more fill lights for the shadows caused by the first lights. Classic addictive behaviour.

I once lived in a city that had replaced street lights that cast light in a circle with modernised ones that cast a sharply delimited rectangle of light on the road, and didn't waste light in other directions.

The thing was, the roads of this city were arranged as a footpath, then a grassed area with trees, then the lights, then the roadway. Only after the city had rolled out thousands of these lights did someone notice the footpaths were now much darker. And also the footpaths were quite uneven, due to the trees' roots - a problem the lights had previously been keeping under control.

It's now common, in winter, to see groups jogging on the road.

> Thorp notes that modern CCTV cameras are “pretty great” even at low-light levels, while harsh light makes it hard for both human eyes and digital sensors to see.

That’s a weird thing to include. That sounds like an argument _for_ more aggressive lights. I didn’t expect to see a “think of the surveillance system”

I'm surprised it didn't suggest using red LEDs without phosphorescence, which has several advantages:

1. Red light preserves your dark adaptation

2. It doesn't have as much of an impact on your circadian rythm

3. Not using phosphorescence can increase the lifetime of the light, since you don't have to worry about the coating degrading

4. Red light is less energetic, so could potentially use less power.

5. Since an LED without phosphorescence is a single wavelength, telescopes (and binoculars) can use a narrow band filter to filter out the light pollution, without blocking most of the light from celestial objects.

Our city recently went on a crusade on replacing all of the high pressure sodium bulbs with LEDs, with the justifications of driving safety and energy savings. I agree that these are important, but the LED bulbs they chose are actively hostile to homes and pedestrians. They are blinding. You can't look at them. I have one outside our house in the main viewing angle and we need to close our shades as soon as they are turned on.

I am generally for a light government touch, but I think excessive light and sound are forms of pollution and should be generally regulated in a not-overly burdensome way (give people fix it tickets etc). Policing excessive light, and excessive blue light, would be pretty trivial. And I think cameras that automatically ticket loud vehicles would be amazing.

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.

I've started doing this in my home. All lights are smart LEDs. At 8pm, they shift warm, 80%. From 9pm-10pm, they go from 80% to 0%. At 7am, they start going from 0% to 100% cool (I work from home and it helps with focus).

Having my environment reflect the patterns of nature has really been a nice change.

All the car headlights for new cars in Canada are LED and it makes driving at night painful and dangerous. So many times I’ve been nearby blinded by them and I can’t see anything ahead. And it actually physically causes me pain.

I read through most of the article but didn't see motion sensors mentioned. A lot of suburban streetlights are lighting up empty streets at night. With a combination of motion sensing and LEDs, lighting could follow pedestrians. Cars really don't need street lights in most cases but even then, in higher risk areas, motion sensors could turn on streetlights just as long as needed.

> 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.

I am Dutch but live in Canada, and when I visit family in The Netherlands, I always notice how much darker it gets during the night, even when my family lives in a larger town than me.

For those in the northeastern US, I highly recommend a visit to Mesawisla in Maine, it's a national dark sky park with cabins and an AMC lodge that provides fantastic food.

I wondered if a city-wide synchronised Pulse-Width-Modulation of LED lights could allow astrophotography (or even naked-eye astronomy) to be possible again, with a filter synchronised to the off-cycle.

The lights are not just impacting space but ecosystems switching to LEDs can save ecosystems too.

We have been working hard on this in New Zealand, in the South Island

We started in Tekapo (https://www.darkskyproject.co.nz/) which being rural with a very low population density, and mountainous and with existing observatories to protect

In recent years the effort has moved into the cities (https://www.dunedin.govt.nz/council/policies,-plans-and-stra...)

Interestingly people who live on hills, overlooking the suburbs, complain the lovely view of the sparkling streets was going dark!

But not only does it preserve the stars it is much cheaper, so not going back

Point is: this can be done and the nighttime rewards and financial rewards make it worthwhile

I read the entire article and am really glad the author took time to write this down and for OP for posting. I am so tired of poor (mostly outdoor) but also indoor lighting. I have felt crazy feeling that the so-called "better" LED's in parks and on paths have felt like less lighting. Unfortunately I think changing things (in the US) often requires proving harm...science and aesthetics don't seem to matter much at all many place.

Since I picked up a Pixel phone, I've been doing some amateur astrophotgraphy, and mostly from the balcony at my apartment.

However, I live in a built-up urban area, and my home is absurdly light-polluted. Like, you wouldn't believe it! The parking lot here is ringed with flood lamps that are aimed into our windows. So every hundred feet or so, there is a bright-as-the-Sun lamp in my face, and with a clear view, I can spot about five of them.

So from my balcony, my only hope to get some darkness for the camera is to get into shadows. The railings provide a band of shadows that I can use to block the floods from getting on my lens. So if I position the camera juuust right, it kinda feels darker than it is, and I've got to say I've captured some impressive starfields, down to magnitude 9 or dimmer, including bodies such as Uranus and 4 Vesta.

I also found that the ballcourts in the rear of my property provide this unique "cave" situation with lots of shadows where I can capture the sky directly overhead, and to the west. This is how I photographed the last lunar eclipse.

Now that's my view to the west and 225° (due southwest). If I go on the other side of the property to look east, I've got the same crazy situation with flood lamps, but there's basically no way to hide in shadows. I literally cannot photograph anything rising in the east if it is dimmer than the Moon.

So really, my astronomy hobby mostly consists of doing some great editing, curation, identification, and mostly simulation from the comfort of the air-conditioned indoors. I enjoy what sightings I can while outdoors, and that's included some meteors, the ISS, Tiangong, and a few Vandenberg launches. We're still hanging in there!

I would 100% rather have a truly bright and lively city at night than a visible night sky. More than half the year is in the winter ffs!

The writing style frustrated me immensely.

tl;dr: Cheap cool-white LEDs cut energy but worsened light pollution; warmer, dynamically dimmable LED fixtures/infra fix it but lower costs tend to win.

I hate outdoor LED lights so much, I won't be surprised if a couple decades or centuries from now we discover that these things have been doing permanent damage to people's eyes. It's getting harder and more unpleasant to walk at night, I can't see and my eyes legitimately hurt every couple of minutes.