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Comment by xbmcuser | Hacker News Reader

Most people do not realise how much light and haze pollution we have today compared to 200 years ago. And how visible the stars were. Even remote places today are not the same as the atmosphere still has more particles compared to 1800s

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This picture shows the difference after the city of Dunedin, New Zealand, changed all its sodium lights to shielded LEDs: https://i.redd.it/hxxp2c3ksdh71.jpg

The color temperature of sodium lights is so much better at night.

Also sodium lights don't create so many headache-inducing shadow patterns.

For example, a street I walked by regularly for almost whole my life recently (in the last few years) got its lighting replaced - each sodium lamp is now replaced with a LED array with no (or ineffective) diffusor. In other words: each spherical source of light got replaced by a bunch of point sources.

Last time I walked down that street during night hours, I got a vague feeling as if I was playing an old videogame, because both the road and the sidewalk looked like a low-resolution texture viewed up close: full of smudgy blocks that result from texture upscaling. Except those blocks moved in a weird dance, making my head spin when I focused too much on it, kind of like looking at moving Moiré patterns.

Turns out, this was the pattern of shadows thrown by leaves of a tree, when illuminated by half a dozen point light sources.

That's my only complaint, though. LED lights are a win overall.

San Jose used sodium lamps for years in deference to Lick Observatory, which is on Mt. Hamilton about 15 miles east of the city. The biggest advantage of sodium lights over incandescent for astronomy is that the spectral lines are very distinct and easy enough to filter out when doing scientific studies; incandescent, on the other hand, floods the spectrum broadly up to visible light.

I believe LED lamps have similar properties to sodium, although I'm not sure how exact they are compared to sodium lamps—there might be greater variance in the spectra emitted due to material differences; whereas all sodium lamps are arcing through a common atomic element and have very predictable wavelengths.

I have only had the pleasure to see the milky way once. It was in the middle of a loan stretch of road in arkansas. I have not seen it since then, 25 years ago. I am the only person in my neighborhood who turns off the porch light at night. I want to see that again and to share it with others. But alas I do not think it will happen :(

Have you not had the chance in 25 years to go somewhere that gave you a decent view of it? Camping or a farmstay?

overcast and raining...

For 25 years?

well yeah... most of the things I like to do are in the city. So it just does not come up very often. When it did...

When I was a grad student at Penn State, we camped out at Cherry Springs and saw the milky way. It was humbling, and I recommend it to every person at least once in their life

I've seen it at a couple places. One is Lowell observatory in Flagstaff AZ. They have pretty good light conditions despite being in a city. Second is in certain national parks which tend to be away from any big city. Third was on a plane flight over the pacific ocean.

I lived and worked in a small town in the Mojave for close to a decade. One of the few perks of living there was the dark sky - the milky way for example was eminently visible on most nights in a way I think most people never see.

https://www.darksky.org btw

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