My favorite mysterious light sources is a triplet off the coast of Newfoundland: https://www.lightpollutionmap.info/#zoom=6&lat=5798060&lon=-...
I assume it's some sort of offshore rig.
What are the mysterious light sources on light pollution maps?
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Re: What are the mysterious light sources on light pollution maps?
#92Light analysis is surprisingly noisy.If you want to do it right, you have to screen out or control for cloud cover, reflections, moon light, oil well fires, and also account for satellite position and the local time at night the image was originally taken. The first four, particularly the first, are easier said than done (e.g., still waiting for NASA to publicly release VNP46A2).
Re: What are the mysterious light sources on light pollution maps?
#93I 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.
Lucky you. I had to drive six hours to watch the Perseids. The nearest dark site to Chicago is Mark Twain National Forest in Missouri.
Re: What are the mysterious light sources on light pollution maps?
#94The map of the United States raises an interesting question. There is a pretty distinct line down the middle, with nearly opposite light/dark patterns on different sides of the line. To the east, it is mostly bright areas with islands of dark. To the west, it is mostly dark areas with islands of bright. If you look at a regular map, nothing really stands out to explain the difference. It is not like there is, say, a…
Curiously this lines up with the locations decimated by the Dust Bowl [1]. There was a mass migration of millions of people westward towards California during the 1930s once the agricultural industry there collapsed.
The proximate cause for that line might be farming techniques poorly adapted to the prairie ecosystem which caused a massive ecological collapse.
Re: What are the mysterious light sources on light pollution maps?
#95As someone working in the greenhouse lighting industry, I might have some insight on this:
1. there is an existing technology called energy screen/curtain, with the primary function of retaining heat, but can also reduce light pollution by an order of magnitude.
2. light that escapes is essentially money lost, however it alone does not justify the use of energy screens.
3. as long as farmers have access to (relatively) cheap heat and electricity, they won't invest into this technology.
4. for the time being, it's a regulatory issue, just like water use (a single plant use 2-2.5 l/day), supplemental co2 use and nitrate recirculation from runoff water.
Re: What are the mysterious light sources on light pollution maps?
#96I 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…
Same thing with Berlin. West Berlin has a whiter glow while East Berlin is yellowish. Relevant: https://www.citymetric.com/horizons/you-can-see-berlin-s-eas...
Re: What are the mysterious light sources on light pollution maps?
#97Earlier quoted context omitted.
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.
Iceland is your best bet.
The list of permanent lava lakes posted by and onychomys includes none in Iceland. https://en.m.wikipedia.org/wiki/Lava_lake
Re: What are the mysterious light sources on light pollution maps?
#98What are all the light sources in the ocean between Taiwan and South Korea? I'd assume shipping, but what about the other shipping lanes, those don't look so obvious compared to that piece of ocean
Re: What are the mysterious light sources on light pollution maps?
#99Earlier quoted context omitted.
Yellow glow is understandable, but check out this purple one https://www.cbc.ca/news/canada/windsor/not-northern-lights-g...
Purple makes sense. Blue and red are the colors of light that are most effectively absorbed by chlorophyll-pigmented plant leaves. Yellow would be a lot less efficient because more would reflect off the green leaves.
Magenta is the complementary (opposite) color of green.
Re: What are the mysterious light sources on light pollution maps?
#100What are all the light sources in the ocean between Taiwan and South Korea? I'd assume shipping, but what about the other shipping lanes, those don't look so obvious compared to that piece of ocean
Squid fishing maybe?
"Fishing trials using LEDs (9 kW) and different numbers of MHs were carried out in August and September 2009" from https://www.researchgate.net/publication/256998066_Catch_per...