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Light Trespass
February 8, 2006 7:06 AM   Subscribe

"Light Pollution - and the return of the night" (more inside)
posted by slimepuppy (54 comments total)

 
Geoff Manaugh has written a guest post for the design blog Inhabitat about "light trespass" or "light that has trespassed its terrestrial limits and now competes with the heavens above, blocking out the stars and forming a counter-astronomy". He uses some striking images to show the effect of urban lighting in its neighbouring areas.

See also on his entry on the the effect of the WTC floodlights on the local birds.

Let's all remember to turn down the light on National Dark Sky Week in April.

(via BLDGBLOG, previously discussed here.)
posted by slimepuppy at 7:08 AM on February 8, 2006


I freaking hate light pollution.

That is all.
posted by Floach at 7:09 AM on February 8, 2006


In most metropolitan areas, it's merely an hours drive to a dark enough area to see all the stars you wish. And...

There's a National Dark Sky Week?
posted by j.p. Hung at 7:14 AM on February 8, 2006


Those images are crap to prove this point (although they are rather nice photos).

By definition, they are exposed until they are bright enough. So if there was less light pollution, he would just use a longer exposure and the photo would end up the same. And vice versa. So the photo says nothing about the level of light.
posted by smackfu at 7:19 AM on February 8, 2006


I think the idea was to provide a visual comparison to what the naked eye would be able to see?
posted by slimepuppy at 7:35 AM on February 8, 2006


When the eastern power grid failed, from Ontario to New York City, in August 2003, it revealed something many city dwellers had never seen: from horizon to horizon, a sky full of stars.

I hear many people say that, but in fact, at least in NYC, it wasn't true. There was plenty enough lighting from miscelaneous places that the stars were barely more visible than any other night.

More likely those folks just heard others say that and looked UP for the first time in years.
posted by HTuttle at 7:38 AM on February 8, 2006


HTuttle, it's similar in (my area of) London. The light pollution is not complete. You can see stars on a clear night just fine.

But when the lights go out _completely_ you see that there are so many stars in between all the stars you normally see. It's a rare occurence that a lot of people aren't actually necessarily aware of. The difference between an urban starry sky and a proper rural starry sky is quite immense.
posted by slimepuppy at 7:45 AM on February 8, 2006


In Toronto, it definitely WAS the case that you could actually see the stars for a change. It was amazing, I sat out on my balcony and watched shooting stars for like 2 hours. Believe me, that's not something you could have seen if the power was actually on.

I kinda got bored of the article after a while though. My favourite comment about light pollution screwing up natural rhythms though:

Grown men watch television for hours at a time.

That gave me a chuckle indeed.
posted by antifuse at 7:47 AM on February 8, 2006


This post kinda detroys the arguement that dark skies are best. Well lit beautiful things are far more interesting to me than the stars.
posted by Keith Talent at 7:53 AM on February 8, 2006


In most metropolitan areas, it's merely an hours drive to a dark enough area to see all the stars you wish.

You should head on out to the Grand Canyon on a clear night in summer and you'll change your tune on this. A true lack of light pollution is dramatic and not as easy to find as you say. Plus - and I'm not saying the urban areas we call home need to be returned to unspoilt nature - but who wants to drive an hour to be able to see stars, sunsets, leaves changing color...
posted by scarabic at 7:55 AM on February 8, 2006


At last, a plus side to living out in the boonies.

-plays banjo-
posted by ELF Radio at 8:02 AM on February 8, 2006


Good to see that Africa and North Korea are doing their part to fight at least one kind of pollution.
posted by dgaicun at 8:03 AM on February 8, 2006


Neighbors who stayed and rode out the storm told me that the same thing was true in the aftermath of hurricane Katrina. Of course they probably preferred looking up at the sky to the alternative.
posted by localroger at 8:14 AM on February 8, 2006


On the western end of Canal Street in NYC (near the entrance to the Holland tunnel), there is a massive video billboard that runs 24 hours a day. Directly to the opposite side of the jumbotron-type billboard is an small three story apt building. As one sits in traffic, you can see the inside of the rooms (one kitchen in particular) constantly change color as the light floods into apartments. Light pollution indeed.
posted by R. Mutt at 8:20 AM on February 8, 2006


At least in the 70's, Tucson, Arizona had regulations to keep the sky darker, due to the UA observatories, both on campus and up the mountains. It was nice!

In suburban and rural locations, street lights are stupid. All they do is make it impossible to see anything that isn't under the lights. Obviously, this doesn't matter where there is no dark inbetween. None the less, I find my vision best when not blasted by the glare.

In my young teens I discovered the awesome joy of walking out into the middle of a frozen lake on a dark night. It was like being on the moon! The snow glittered in answer to the stars. This was before everyone started putting mercury vapor lights in their yards. YUCK!
posted by Goofyy at 8:34 AM on February 8, 2006


When I visited Amsterdam I was struck by how much less ambient light there was at night than there was back home (I lived in Hoboken at the time). I never did figure out whether it was a deliberate decision to curb light pollution, or if it was just a function of being in a smaller urban area.
posted by clevershark at 8:52 AM on February 8, 2006


At least in the 70's, Tucson, Arizona had regulations to keep the sky darker...

Summer 2003. Was in Tucson in a rental car, top down, killing time cruising. Passed a baseball field with Cheap Trick playing. Music and city lights receded as I went uphill for a long stretch. So much sky and so many stars it felt like I was heading into low orbit.
posted by hal9k at 8:53 AM on February 8, 2006


Did you notice the google ads at the bottom of the page were for high output flourescent lighting?
posted by Roger Dodger at 9:07 AM on February 8, 2006


Roger Dodger, that's rather hilarious.

Wonder how many people read that post and think "hey, I could really do with more light around here..."
posted by slimepuppy at 9:13 AM on February 8, 2006


I worked at a plane arium for a long time (if you watch the South Park episode on plane ariums look at the logo on the guys chest...it looks like a manatee, and the place I worked also happened to have the oldest captive born manatee in the world (Snooty) on the other end of the complex, with a museum in between) and when the new police station/mayors office was built across the street they added sodium arc lamps every 10' or so, ignoring our pleas to hood them. In the beginning, our boss took a portable YAG laser to the roof and would hit the light sensors on top (carrying a very heavy laser up 4 stories to then break countless laws was very tedious)...that would give us several hours of cleaner viewing after our star shows when we brought people to the observatory. Eventually, we were able (it took many years and a LOT of work) to get the city to hood the lights, but it still blows me away how insensitive they were to our needs. The plane arium in Bradenton is very unique and a treasure of the town (which sadly burned down and sat dormant for several years, but has just recently been rebuilt)...one would think that would garner some consideration...but alas, mentioning 'light pollution' to most city officials draws a blank stare.

Something MeFites can do (previously mentioned) is support the International Dark-Sky Association
posted by gren at 9:20 AM on February 8, 2006


The light pollution in Calif is nuts. I remember being in Joshua Tree and still being able to tell where LA was by the glow. I live near Berkeley these days and you can only see a handful of stars. One of the best things about Yosemite is the star gazing.

There are solutions that are compromises- street lights that are shielded in such a way that they only light the area below them, for instance.

Wikipedia's entry is worth checking out, especially towards the end where it talks about the ecological effects some people suspect are linked to too much light.
posted by small_ruminant at 9:26 AM on February 8, 2006


A pragmatic reason to prefer a dark sky.
posted by moonbiter at 9:36 AM on February 8, 2006


The real problem I have with outdoor lighting is that it is so poorly designed. Much of the light never hits the ground. A good part of it shines into the sky, a good part hits the ground so far away from the lamp that it's useless, and a good part shines right into your eyes -- that the glare means you can't see as well.

Properly hooded fixtures not only can save you a bunch of money, you can acutally see the ground far better than you can with current lights.

When you take off in a plane at night, look at all the lights you can see below. All those points of direct light from a fixture -- that's all wasted light. It's not even hitting the ground -- it's going up and out.

If all fixture were hooded, it wouldn't eliminate light pollution -- light would still bounce off the ground and up into the sky. But it would dramatically reduce it, let us use far smaller lamps, which means we'd save tons of money, and we'd both see the stars and the ground better.

That's the point of these lights, right? So you can see things on the ground?
posted by eriko at 9:39 AM on February 8, 2006


ClearSkyClock has some interesting maps that show light pollution effects as measured by satellite. For example, here's where I live in Seattle. Doesn't look like a single hours drive is going to cut it.
posted by olbiadle at 9:42 AM on February 8, 2006


but who wants to drive an hour to be able to see stars, sunsets, leaves changing color...

I have to drive so see the beach, look at a mountain and depending on where I live, yeah, to see the leaves change. Hey wait...did you say you can't see the sunset?? Light pollution indeed!!
posted by j.p. Hung at 9:47 AM on February 8, 2006


Gren's link, the International Dark-Sky Association, is probably the best source for information about this topic.

Another good site to check is called The Night Sky in the World. They have some very nice maps of light pollution around the world.

...

Personally, I think there's clearly a place for well-lit cities, but a lot of the light we create is pretty unnecessary and could be cut down on without a loss of safety. And I'd rather see the Milky Way than a bunch of ugly K-Mart parking lot lights any day of the week.

I came back to the US from Taiwan a couple years ago, and that was one of the big reasons. All too often I'd hear little kids say "Look, Mommy! A star!" (note the singular) only to have the mom say "No, dear, that's an airplane." Too many people are being deprived of the opportunity to see how beautiful the night sky truly is.
posted by jiawen at 9:47 AM on February 8, 2006


For the record, Tucson/Pima County still has those lighting codes but they still suffer from things like billboards and sports park lighting...
posted by bhance at 9:49 AM on February 8, 2006


j.p. Hung writes "In most metropolitan areas, it's merely an hours drive to a dark enough area to see all the stars you wish. "

You probably aren't seeing anything below magnitude 3-4 within even 1 hours interstate travel time of most major metro areas. You sure as heck aren't seeing, for example, the faint stars that make up Orion's Shield. The milky way won't be visible as anything special because the background light pollution is obscuring the dark sky needed to make it stand out.
posted by Mitheral at 9:49 AM on February 8, 2006


I wonder if the reseach showing that nighttime exposure to light stimulates cancer tumour growth will add voices to the call for a reduction in artificial light pollution.
posted by raedyn at 9:58 AM on February 8, 2006


hey, i just had an idea.

one of the reasons that big telescopes and observatories are located way out in the boondocks is because of urban light pollution. but i have to wonder if there's a way around this.

most outdoor lighting in an urban area is powered off a common electrical grid running 60 Hz AC. as a result, these lights actually turn on and off 120 times per second - faster than the eye can see.

presumably because they are all powered by the same grid, all the lights should be blinking on and off at the same time. that means near the zero-crossings there should be near-darkness. (this statement is based on a lot of perhaps-unfounded assumptions about the rise/fall times of various light sources.) the speed of light is fast enough that the entire sky then should be blinking on and off as the amount of light to be scattered is modulated.

this should allow for people interested in doing astrophotography in urban areas to sync their cameras to the grid and gate the exposure time so that it falls around the zero-crossing of the AC. depending on the duty cycle chosen, this would mean a longer exposure; but presumably higher contrast since the signal to noise will be higher over the repeated exposures.

are there any amateur astronomers/astrophotographers around here who would know if such a thing already has been done? or if i have made a poor assumption about something - maybe transformers introduce a randomized phase change that makes the whole thing decohere? it would be a cool thing to investigate with some high-speed cameras overlooking a city.
posted by sergeant sandwich at 9:59 AM on February 8, 2006


These are some really cool pictures.
posted by Mitheral at 10:10 AM on February 8, 2006


sergeant sandwich writes "most outdoor lighting in an urban area is powered off a common electrical grid running 60 Hz AC. as a result, these lights actually turn on and off 120 times per second - faster than the eye can see."

Two problems:
1) Incandescent bulbs don't flicker this way.

2)Single phase AC power is actually one of three taps off of a three phase power source (this is why high tension wires come in threes). In a wide area those peaks and valleys would be only 120 degrees out of sync with the other two legs of the 3 phase power.
posted by Mitheral at 10:14 AM on February 8, 2006


as a result, these lights actually turn on and off 120 times per second

Even if the lights were powered by 60Hz AC, they'd just be dimming imperceptibly, not going completely dark. The glowy bits don't extinguish immediately and then fire up again; otherwise you'd get a strobe light.

Even then, I suspect that a lot of outdoor lighting is DC.
posted by mendel at 10:15 AM on February 8, 2006


I'll heartily second jiawen's observation: We use -- we think we need -- far more light than we actually do need. I drive through the country at night at pass one small business after another who light their parking lots all night long, or houses who run their external lighting all the time. It's just not necessary. Frankly, I find it kind of offensive, light pollution aside, because of the plain waste involved.
posted by lodurr at 10:17 AM on February 8, 2006


seageant sandwich,

It is definitely an interesting thought, but I'm afraid I don't think it has practical applications for astronomy. I strongly suspect that the vast majority of light sources fades too slowly for there to be observable periods of darkness in between the flashes. I really don't think glowing plasma or filiments don't go dark in 1/120th of a second. And everything on DC power (such as automotive lights) burns steadily.

This sort of synchronization is done, however, in film and television production when TV displays are in the field of view, to prevent flickering and other artifacts in the recorded film or video. It is not, however, necessary to synchronize your film or video camera with the regular sources of light which people use to see. I think that shows that the lights simply don't get dark enough for synchronization to be relevant.

But even if it was dark for half of every AC cycle how do you propose doing your observing then? It's no good for optical observing, of course. Astrophotography with a current film and digital cameras relies on shutters open for a lot longer than 1/120th second. You'd have to open and close the shutter 60 times a second (like a sped-up movie camera), which would probably create a lot of vibration, a no-no for capturing a magnified image. Astrophotography with CCD cameras isn't that different. If you wanted to avoid fluttering a shutter you'd have to read out the CCD 60 times per second, and so far as I know it takes seconds to do it even once.

On preview: what Mitheral and mendel said.
posted by Songdog at 10:23 AM on February 8, 2006


The thing that I see a lot now is McMansions lit up from exterior flood lights shining in on the house. There's no other point to these lights than to say, "look at my house, doesn't it look expensive?" It looks really stupid and since the lights are on the ground pointing up at the house so they really generate a lot of light pollution.
posted by octothorpe at 10:25 AM on February 8, 2006


Also, I definitely cannot find a dark sky within an hour of New York City anything like what I can find in western Massachusetts. And I have not found a dark sky anywhere in western Massachusetts that matches what I found in Hawaii. Sure, it's darker in the suburbs where I live than in the city where I work, but with my naked eyes I still can't see anything fainter than third magnitude from my yard, and that's just terrible. It's fewer than three hundred stars in the entire sky, most of which is further blotted out by local glare In a real dark sky situation between ten and a hundred times as many stars are visible to the naked eye.
posted by Songdog at 10:28 AM on February 8, 2006


The only time I've ever seen an unpolluted sky was driving cross-country -- couldn't tell you exactly where we were -- and looked out the sunroof to see such a huge number of stars that it knocked me on my ass (figuratively). We ended up pulling over getting out, and staring up into the sky until our necks hurt.

Of course, I've only lived in major metropolitan US cities, so perhaps this is not surprising.
posted by davejay at 10:41 AM on February 8, 2006


Oh yeah, and living in Los Angeles now, I can say that while most nights there's no cloud cover (and so no light being reflected back downwards) you can always tell the cloudy nights because it looks like early evening outside, all night long -- the sky just glows and glows.
posted by davejay at 10:42 AM on February 8, 2006


But even if it was dark for half of every AC cycle how do you propose doing your observing then? It's no good for optical observing, of course. Astrophotography with a current film and digital cameras relies on shutters open for a lot longer than 1/120th second. You'd have to open and close the shutter 60 times a second (like a sped-up movie camera)

i know - wasn't suggesting a mechanical shutter - something more like gating the CCD bias with a timing circuit that is triggered by a zero-voltage on the AC power. gate, read bits, store to file; gate, read bits, store to file; repeat for a while then add all the files up.

the points about incandescents are valid - but i get the impression that most light pollution comes from sodium arc discharge lamps (streetlights) and halogen floodlights. if you point a camera at a streetlight and wiggle it around while the shutter's open, you'll see a streak that pulsates on and off. this leads me to believe that those lights actually do go dark between cycles. (i believe the recombination time for a sodium plasma in a little tube like that is pretty short.) dunno about the halogens, though, but since they use a filament that gets hot, i suspect they stay on all the time.

re: mitheral's comment - good point about the 3-phase taps. i think it still is a reasonable idea if all the lights in a certain region have the same phase. that sounds pretty unlikely, though. ah well!
posted by sergeant sandwich at 10:48 AM on February 8, 2006


Anecdotal: Most of the studies on outdoor lighting and crime show that lighting increases crime, not reduces it.

Something that I noticed growing up in LA was that only the most expensive neighborhoods had no street lights.

I really wish that once a month they'd just turn off all the lights for a few hours so we could see the sky again.
posted by loquacious at 11:09 AM on February 8, 2006


Beautiful evening; you can almost see the stars.
posted by small_ruminant at 11:14 AM on February 8, 2006


sergeant sandwich writes "the points about incandescents are valid - but i get the impression that most light pollution comes from sodium arc discharge lamps (streetlights) and halogen floodlights"

Halogen's are still incandescents. They just use a high pressure envelope around the filament to allow hotter filaments to be run without melting.

sergeant sandwich writes "good point about the 3-phase taps. i think it still is a reasonable idea if all the lights in a certain region have the same phase. that sounds pretty unlikely, though. ah well!"

In most places the power is split into single phase by neighbourhood substations, that's a pretty small area of differentiation.

loquacious writes "I really wish that once a month they'd just turn off all the lights for a few hours so we could see the sky again."

That would be sweet. too bad people would probably freak out thinking there would be increased crime.
posted by Mitheral at 11:25 AM on February 8, 2006


I've never seen this phenomenon in the city before (self link) - does it have anything to do with ambient light pollution?
posted by PurplePorpoise at 11:36 AM on February 8, 2006


rather - where the sun and stars are both visible at the same time in a relatively tight arc of the sky
posted by PurplePorpoise at 11:37 AM on February 8, 2006


It looks to me like the white spots in the picture are actually water or ice on the window that camera was shooting through.
posted by Irontom at 12:07 PM on February 8, 2006


Rising power costs will handily solve the problem of light pollution, or at least greatly reduce it. Unless someone's planning to build a nuclear reactor a month for the next 20 years, anyway.
posted by slatternus at 12:30 PM on February 8, 2006


No, I assure you those are stars - I took the snapshot using a disposable camera while rocketing down I-something-or-the other during Thanksgiving break lo those many years ago.
posted by PurplePorpoise at 1:12 PM on February 8, 2006


I know a place about an hour from NYC where at times I've been able to see the Milky Way. No stars is one of the few things I dislike about the city.
posted by TheOnlyCoolTim at 5:41 PM on February 8, 2006


I lived in the Indian Ocean before coming back to the States.
The Comoros islands, or les Iles de Lune (Islands of the Moon).

There, the stars were so bright it was as if you felt you could reach your hand up and scoop them down. The Milky Way was like a river flowing across the sky.

My wife and I used to go for long walks on nights of the full moon with large fruit bats flying overheard and makis (lemurs) screeching atop the palm trees as you walked by.

Now we walk the streets of DC, where I rarely look up.
posted by pwedza at 5:57 PM on February 8, 2006


Here in Flagstaff we love the night. Officially my town is the first International Dark Sky City.
posted by RockyChrysler at 7:11 PM on February 8, 2006


Purple Porpoise, that picture is somewhat of an impossibility. I've taken pictures nearly an hour after sunset with an exposure time of 30 seconds or so and I could see some stars but not that many. Also the sky was filled with the scattered blue light. There is no way you could get the stars to show up in the length of exposure from a disposable camera.

I don't know what is going on with that picture, but it is not the sun and stars in the same shot. If you could capture the stars on a disposable camera, many more people would be taking pictures of the stars.
posted by Phantomx at 3:29 AM on February 9, 2006


PurplePorpoise writes "No, I assure you those are stars"

Stars don't show a disk and the disks don't seem to be a photographic artifact as the antenna and dirt on the windshield are crisp. I'm betting water on the window too. It could also be a dirty lense on your camera.

Because the eye can see much more latitude than even the best film you may have been able to see the stars but your film wouldn't have captured it. In general, even with the widest latitude colour print film, your only going to get about 7 stops between the brightest and dimmest exposed items that are actually visible without being all black or completely blown out. Your sun is blown out, your sky is visible and sunlit (say about f11@1/60 on 100iso film). The brightest stars start being visible on film some where about f1.8@1/8s on 400iso, which is around 10 stops difference.

As a double check look at the tower/billboard thing on the horizon. To the right a distance about the height of the tower right at the border between brown and blue sky there is a double "star" that isn't being tinted by the brown sky.
posted by Mitheral at 7:08 AM on February 9, 2006


Thanks Mitheral.

Wierd. The reason I took the shot was because what I saw with my eyes was so odd. Didn't think the camera would/could capture it... and maybe it didn't.

I was driving so, no, I wasn't on drugs/psychadelics at the time.
posted by PurplePorpoise at 7:51 AM on February 9, 2006


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