Last night @astrokiwi.bsky.social showed me that you can actually see the Milky Way from inside the city of Christchurch!
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The population of Regina, Saskatchewan is about 200k, Christchurch is 400k. Somehow, Regina has worse light pollution. I don't think the city is more concentrated, it's in the middle of the prairies, there's literally nothing to keep it from sprawling. (Is it just the snow on the ground? I don't know what time of year these measurements are taken.)
I'll have to do a bit more reading, but it's very interesting to me that NZ cities seem to be much darker than equivalent size Canadian cities.
@sundogplanets What are the streetlights like? Does one have covers, directing light down? Is the light colour temperature different?
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@sundogplanets @grb090423 The wind in Regina keeps pushing the outskirts towards downtown. That’s why it’s more concentrated.
@NunavutBirder @grb090423 Best theory I've heard so far!
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The population of Regina, Saskatchewan is about 200k, Christchurch is 400k. Somehow, Regina has worse light pollution. I don't think the city is more concentrated, it's in the middle of the prairies, there's literally nothing to keep it from sprawling. (Is it just the snow on the ground? I don't know what time of year these measurements are taken.)
I'll have to do a bit more reading, but it's very interesting to me that NZ cities seem to be much darker than equivalent size Canadian cities.
@sundogplanets Queenstown is far smaller, but I stopped on my tracks getting out of a house or a restaurant there and seeing the Milky Way like you can’t really see it in Finnish countryside (at least in S/SW Finland).
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The population of Regina, Saskatchewan is about 200k, Christchurch is 400k. Somehow, Regina has worse light pollution. I don't think the city is more concentrated, it's in the middle of the prairies, there's literally nothing to keep it from sprawling. (Is it just the snow on the ground? I don't know what time of year these measurements are taken.)
I'll have to do a bit more reading, but it's very interesting to me that NZ cities seem to be much darker than equivalent size Canadian cities.
I think snow reflection makes a huge difference. We got a dusting of snow the last couple of days (doesn't usually snow here) and last night the cluster of houses (and lights) on the hills across the valley were glowing very brightly. I was confused about what was happening but then I thought about the snow. Plausible theory?
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@sundogplanets Snow is a great theory. I would also be curious about the age of the stock of streetlights in each city. Dark sky advocacy looks relatively well developed in NZ.
I don't think so. But I hope it will.
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The population of Regina, Saskatchewan is about 200k, Christchurch is 400k. Somehow, Regina has worse light pollution. I don't think the city is more concentrated, it's in the middle of the prairies, there's literally nothing to keep it from sprawling. (Is it just the snow on the ground? I don't know what time of year these measurements are taken.)
I'll have to do a bit more reading, but it's very interesting to me that NZ cities seem to be much darker than equivalent size Canadian cities.
My theory: trees! All the trees in Regina look like they are deciduous on google maps. Seasonal differences might prove the point?
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The population of Regina, Saskatchewan is about 200k, Christchurch is 400k. Somehow, Regina has worse light pollution. I don't think the city is more concentrated, it's in the middle of the prairies, there's literally nothing to keep it from sprawling. (Is it just the snow on the ground? I don't know what time of year these measurements are taken.)
I'll have to do a bit more reading, but it's very interesting to me that NZ cities seem to be much darker than equivalent size Canadian cities.
@sundogplanets the colours in the center look the same to me? Blob looks bigger, or is that just a different scale?
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The population of Regina, Saskatchewan is about 200k, Christchurch is 400k. Somehow, Regina has worse light pollution. I don't think the city is more concentrated, it's in the middle of the prairies, there's literally nothing to keep it from sprawling. (Is it just the snow on the ground? I don't know what time of year these measurements are taken.)
I'll have to do a bit more reading, but it's very interesting to me that NZ cities seem to be much darker than equivalent size Canadian cities.
@sundogplanets I was just doing some light searching wondering if the lower ozone levels down here would be a factor. Not sure, but https://www.mdpi.com/2073-4433/13/11/1844 suggests nighttime ozone levels at ground level are higher in urban areas, which is interesting too.
I'm also wondering if lower pollution in general is helping. -
The population of Regina, Saskatchewan is about 200k, Christchurch is 400k. Somehow, Regina has worse light pollution. I don't think the city is more concentrated, it's in the middle of the prairies, there's literally nothing to keep it from sprawling. (Is it just the snow on the ground? I don't know what time of year these measurements are taken.)
I'll have to do a bit more reading, but it's very interesting to me that NZ cities seem to be much darker than equivalent size Canadian cities.
@sundogplanets Is that Regina or a Mandelbrot set?
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@sundogplanets Snow is a great theory. I would also be curious about the age of the stock of streetlights in each city. Dark sky advocacy looks relatively well developed in NZ.
@aarbrk @sundogplanets I’m curious how SF compares: it’s so so dark here at night. We barely have any street lighting in many residential neighborhoods. I often have to light my own way with a flashlight when walking around at night.
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The population of Regina, Saskatchewan is about 200k, Christchurch is 400k. Somehow, Regina has worse light pollution. I don't think the city is more concentrated, it's in the middle of the prairies, there's literally nothing to keep it from sprawling. (Is it just the snow on the ground? I don't know what time of year these measurements are taken.)
I'll have to do a bit more reading, but it's very interesting to me that NZ cities seem to be much darker than equivalent size Canadian cities.
@sundogplanets Probably snow, given the distribution of dark night skies around the year at high latitudes. Have a look at Fairbanks, which shows up as brighter than San Diego, a city ~40x the population. For comparison, Juneau, which is rainier than snowy even in winter, looks no brighter than a typical town of its size at lower latitudes.
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@sundogplanets @grb090423 The wind in Regina keeps pushing the outskirts towards downtown. That’s why it’s more concentrated.
@NunavutBirder Regina is the literal opposite of "concentrated". It is full of empty space, most of it paved.
I think the light pollution comes from the fact that no lights ever get turned off. It is as lit (and empty) at 2am as it is at any other time of day. Plus of course all the ginormous trucks with their extrabright lights.
(It may be obvious from the above, but I'm not a fan of Rjj.)
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@sundogplanets
It makes such a difference what sort of street lights are used and especially where they're pointing. In Montreal, the newer lights only shine on a smallish area straight down, and it's much better than the old ones that blast light in every direction...!@jaddle @sundogplanets This is a very likely explanation. I heard of some places that mandate streetlights not spill upwards, and other places switched to colors (incandescent) that were easier to filter out for visible light astronomy.
Now that we have LEDs that can be set to nearly any frequency or range of frequencies, I would look again at rules for what color(s) they are allowed to emit.
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