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What are the mysterious light sources on light pollution maps?

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21–30 of 146 posts

Re: What are the mysterious light sources on light pollution maps?

#21
post #19
post #12

Earlier quoted context omitted.

Yellow glow is understandable, but check out this purple one https://www.cbc.ca/news/canada/windsor/not-northern-lights-g...

> She said the municipality is trying to find the best way to address the issue, while still considering the economic side. Just make them put tarps over the greenhouses!?

Don't want to run the lights in the day.

Re: What are the mysterious light sources on light pollution maps?

#22
post #8

Ah yeah, in the post's first "unknown light pollution" example, I figured it must be a greenhouse. I was driving through a relatively small town one time and was a bit freaked out by this ominous yellow glow off in the distance. Like, the whole sky was glowing [0]. I ended up driving out to try to find the source, and discovered it was a huge greenhouse/farm. Luckily not an extraterrestrial landing zone or so on ;) […

It looks even more amazing when it's cloudy and the ground is covered by snow. You can go skiing in the forest at night and you won't need any additional lights.

Re: What are the mysterious light sources on light pollution maps?

#23
post #19

Earlier quoted context omitted.

> She said the municipality is trying to find the best way to address the issue, while still considering the economic side. Just make them put tarps over the greenhouses!?

Don't want to run the lights in the day.

Take them off during the daytime. They're not permanent installments.

Re: What are the mysterious light sources on light pollution maps?

#24
post #6

I flew through the night to Singapore once. I remember two very striking light sources. Firstly, oil well flares in the Middle East. The oil fields are in the middle of nowhere, so they're these huge orange-red blooms set in utter darkness. Secondly, Delhi. The city is brightly lit with streetlights. But there's a suburb (?) to the south, Faridabad, that's as brightly lit, but with a different, whiter, kind of lights…

Prudhoe Bay at the top of Alaska must be something like that, because it's bigger than many major cities.

Re: What are the mysterious light sources on light pollution maps?

#25
post #12

Earlier quoted context omitted.

Yellow glow is understandable, but check out this purple one https://www.cbc.ca/news/canada/windsor/not-northern-lights-g...

I wonder how much money might be saved just by installing shutters to reflect the light (and heat) back into the greenhouse instead of letting it pollute everywhere.

Light perception is logarithmic. There might well be 99% of the light hitting the plants leaves, and 1% escaping to the environment, yet that 1% will only appear a bit dimmer than the original light source.

Re: What are the mysterious light sources on light pollution maps?

#26
> Kiluaea (sic?), as an active volcano, regularly has literal glowing lava occupying the caldera.

Not anymore, sadly: https://www.nps.gov/havo/planyourvisit/lava2.htm

> Beginning in May, 2018, the lava lake that existed inside Halema‘uma‘u crater disappeared and lava flows from Puʻu ʻŌʻō crater have ceased. There is no molten lava or lava glow to see anywhere in or out of the park.

(I would still recommend visiting: the road that encircles the volcano is destroyed, and parts of it are hike-able, and the destruction is fun. And the caldera is even bigger now, and the sulfur vents are interesting, and the landscape is beautiful. And Hawaiʻi is just breathtaking.)

Re: What are the mysterious light sources on light pollution maps?

#27

Earlier quoted context omitted.

I wonder how much money might be saved just by installing shutters to reflect the light (and heat) back into the greenhouse instead of letting it pollute everywhere.

Light perception is logarithmic. There might well be 99% of the light hitting the plants leaves, and 1% escaping to the environment, yet that 1% will only appear a bit dimmer than the original light source.

That's fine, but I'm still curious about the costs involved.

Re: What are the mysterious light sources on light pollution maps?

#28
post #10
post #4

I was looking at light pollution maps just the other day, trying to find places to do astro-photography, and was blown away by how much light pollution there is. Really sucks, because I'd have to drive about 90 minutes out to get into a dark zone.

Only 90 minutes? For me it's at least 3 hours to get to Class 4 on the Bortle scale. Class 2 is probably more than 5 hours. Only alternative is the sea. I'm planning to take a trip to a Class 1 this summer, it'll be hard to find a place that dark that is reasonably reachable though.

NYC? About the same for me.

Re: What are the mysterious light sources on light pollution maps?

#29

> Kiluaea (sic?), as an active volcano, regularly has literal glowing lava occupying the caldera. Not anymore, sadly: https://www.nps.gov/havo/planyourvisit/lava2.htm > Beginning in May, 2018, the lava lake that existed inside Halema‘uma‘u crater disappeared and lava flows from Puʻu ʻŌʻō crater have ceased. There is no molten lava or lava glow to see anywhere in or out of the park. (I would still recommend visiting:…

I wonder if there are some other places in the world I could visit reasonably expecting to see molten lava and all that dramatic looking stuff.

Re: What are the mysterious light sources on light pollution maps?

#30
post #6

I flew through the night to Singapore once. I remember two very striking light sources. Firstly, oil well flares in the Middle East. The oil fields are in the middle of nowhere, so they're these huge orange-red blooms set in utter darkness. Secondly, Delhi. The city is brightly lit with streetlights. But there's a suburb (?) to the south, Faridabad, that's as brightly lit, but with a different, whiter, kind of lights…

Based on the color of light you can see where east and west Berlin were.

The east used gaslamps

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