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Comment by city41 | Hacker News Reader

San Jose also uses orange sodium lights to help reduce light polution for the Lick Observatory.

I agree with the article they have a "gloomy" effect. They are also pretty much the exact same color as the yellow in traffic signals, which can make driving at night a tad more annoying.

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Light pollution is another important side aspect of this. What if, as light becomes cheaper, people/ cities just use more of it? From other comments, it sounds like this is already happening with LED.

LED will pretty much be better in terms of light pollution. With tubes or filaments, you need to make expensive reflectors to prevent the light going in directions you don't want.

LED lighting is much easier to make directional. With LED lighting, the difficulty is making it more isotropic.

Sodium lights are trivial to block using optical filters. This is very common in astronomy.

LEDs + phosphor, not so much, due to their wider spectrum. That less is emitted directly skyward doesn't help if what's reflected off pavement can't be filtered out. (Pavement is surprisingly reflective even though it's "black".)

The main issue I've heard about is that LEDs are generally more wide-spectrum than sodium vapor lamps. This leads to a lot more sky glow (light pollution). There's a good webpage about this here: http://www.flagstaffdarkskies.org/for-wonks/lamp-spectrum-li...

"gloomy" is quite subjective...

I've never observed street light color making driving at night annoying; for the 3-5 second interval the yellow is on.

Just curious, have you ever been tested for color blindness?

The'll probably want to switch to the LED lights then. They produce any light pollution compared to the orange sodium lights. The difference is quite startling.

Definitly not. Sodium lights obly emit a very narrow spectrum of light (esp. the kind used around observatories) which can be easily filtered without losing a lot of the availible light. LED + Phosphor emits a much wider spectrum.

I would definitely get tested for colour blindness. At least in the three cities where I have regularly driven over the last 20 years, the colours are distinctly different.

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