The skies at night, are too darn bright

By Phil Plait | March 21, 2011 1:00 pm

Light pollution is a serious topic.

The term refers to wasted light that goes up into the sky instead of illuminating the ground. Almost everyone on the planet has seen it; anywhere near a city the glow from all that light goes into the sky, washing out the stars. Even far from urban areas, the effects are felt.

The obvious problem is for astronomers, who have to fight this added light when observing faint objects. To do this we have to build observatories far, far from cities, or even up in space. That’s expensive, inconvenient, and honestly just a pain in the rump.

But there are other issues as well: people lose sight of the sky, lose their ties with it. That’s bad enough, but there is also concern that, like with chemical or other forms of pollution, wildlife is affected. Mating cycles, hunters and hunted, sleeping cycles: all are affected by our wasted light.

In the journal PLoS ONE, a paper has just been published about the amount of light pollution in the sky. It’s sobering. Clouds over cities are very efficient at reflecting the lights (the picture above was taken at night, to give you an idea of how bad this is), and the researchers found that the sky brightness can increase by a factor of ten times in Berlin on cloudy nights. Of course, astronomers don’t observe when it’s cloudy, but the other effects on wildlife are still there… and this effect ranges far outside the city.

They created this map of lights in Berlin, in fact, with the goal of increasing the resolution enough to see just where all the bright and dark spots are:

Maps like that will help scientists better catalog the effects of light pollution.

Now, I know some folks may poopoo this whole thing, and not really care that much about how this affects astronomers and critters. Well, think of it this way then: every photon directed into the sky is a photon not helping you see the ground. It’s wasted energy and wasted money. More efficient lighting systems — ones that direct all the light down instead of up — save a lot of money. In many cases all it takes is a cover or other sort of shade over the top of a street light. You’ll need fewer lights, too, again saving money.

Better lighting helps everyone: astronomers, animals, and (city) administrators.

For more information on this, please go to the Dark Sky Association’s website.

CATEGORIZED UNDER: Astronomy
MORE ABOUT: light pollution

Comments (104)

  1. KaneHau

    Move to Hawai’i, we have some of the darkest sky around (especially at 13,769 ft atop of Mauna Kea)

    aloha!

  2. DennyMo

    One common complaint I’ve read about dark skies insitiatives is that we’re exchanging a better view of the stars for increased crime rates. I find this argument very weak, but haven’t found a better rejoinder than a snorted “Bull___”. Is anyone aware of studies that would disprove this objection?

    (KaneHau, you’d have to convince all the new haoles to get out of Waikiki, the night sky sucks pretty bad there, too.)

  3. Michael Swanson

    I’ll never forget the view from atop pitch black Haleakala in Maui. I would have stayed all night, but it was freezing! If I go again I’ll be sure to pack for 10,000 ft weather, sleep in late, and just stare at the sky all night long.

  4. SomeCallMeTim

    Thanks, Dr. Phil… Just yesterday I was looking at the lights in my front landscaping and I noticed one of the tiny spotlights had been knocked and was pointed almost straight up. I thought “I need to go put on some shoes and fix that”. I had read blurbs about light pollution last year and rearranged the lights to limit it, but this one had moved.

    Now, I am sitting at work and cannot alleviate my guilt of not having corrected it. I will wallow in that guilt until quitting time, and fix it when I get home. Dang my laziness!

    {sigh}

  5. … Deep in the heart of Texas!

    I’m going to consider this a Pee Wee’s Big Adventure reference, since that’s where I heard of the song. (Click my name for You Tube video of applicable scene.)

  6. chris

    I took part recently in a survey undertaken by the CPRE http://www.cpre.org.uk to get a better idea of light pollution in the UK.
    In the space of a given week, participants would count how many stars were visible within the four corners of Orion with the naked eye. I think i counted 12 or 13.

  7. Also see this recent TED Talk in which van der Heide discusses night sky in the context of design and architecture:

    http://www.ted.com/talks/rogier_van_der_heide_why_light_needs_darkness.html

    “Lighting architect Rogier van der Heide offers a beautiful new way to look at the world — by paying attention to light (and to darkness). Examples from classic buildings illustrate a deeply thought-out vision of the play of light around us.”

  8. Josie

    @DennyMo

    I suppose all you would need to do is reference what Phil says in this post:

    every photon directed into the sky is a photon not helping you see the ground. It’s wasted energy and wasted money. More efficient lighting systems — ones that direct all the light down instead of up — save a lot of money

    I doubt many rapist muggers or any other mal-intented human is hanging out 15 ft above ground waiting for their next passing victim.

    I am all for more efficient lighting. The current solution (no pun intended, really!) of staggering streetlights to turn of and on at various times of the night is stupid. If light is needed, it’s needed just as much ad 2 am as 3am and if it isn’t needed…then why have it at all?

    Consistent lighting that points where people are actually walking, driving or looking (eg street signs) is what is needed. I would think the expense of additionally lighting the heavens would be a motivator to make it happen.

  9. JP

    @ 2 DennyMo:

    I think you could respond that that’s something of a straw-man argument. These initiatives don’t advocate having dark streets and dark alleys – they advocate having dark *skies*. I’d think that Phil’s suggestion about making sure all the streetlights in a city efficiently direct their light downward ought to help keep crime in check (assuming darkness and crime are correlated, of course) because it would make street lighting less expensive, allowing for more areas to be effectively lit.

  10. I’m always amazed at how much beauty we miss in the sky because of light pollution. It’s really very breath taking when you get somewhere without all the light pollution (I live in LA) and you can see the Milky Way (not to mention the much greater number of visible stars).

  11. David Morley

    Is ground reflection of lights also a problem?

  12. Chris

    I should send this to my idiot neighbors who insist on leaving their porch lights on all night.

  13. Thad Hatchett

    Don’t forget to participate in the Globe at Night project! The new campaign starts tomorrow, March 22nd. Help map the sky brightness in your area. Details can be found at…
    http://www.globeatnight.org/

  14. Nathaniel

    @DennyMo
    You could also put the burden of proof back on them. Ask them for sources to prove that places that have adopted dark skies initiatives have seen a rise in crime rates.

  15. John Paradox

    I always like reporting on Town Meetings in Sahuarita (Arizona, south of Tucson) because they stood up against Safeway when the store wanted to ‘increase lighting for safety’, but the Council supported Dark Skies instead.

    J/P=?

  16. Don’t downplay the impact on human health. The American Medical Association passed a resolution calling for a reduction in excess night time lighting.

    http://docs.darksky.org/Docs/AMA%20Light%20pollution.pdf

    Dark skies advocates want well designed lighting that lights only when and where it is needed and only as much light as is needed. When you frame the debate this way, you find that not many people are willing to argue for poorly designed lighting!

    As part of our outreach here at NOAO, we have built a couple of panels of lights that we take to outreach events. Each panel has several common types of lights that we use to show people the difference between well designed lights and poorly designed lights. Most of the fixtures we got at our local Home Depot (save for the Glarebuster we got online).

  17. fetchbeer

    I think my grandfather once talked about a superhero that would be a friend to all astronomers and stargazers…

    BB Man!

    Shooting out all those lights that shine into the darkness and ruin our view of the sky.

    I grew up out in the country, and now that I live in the city, I truly miss the awesome night sky that I grew up with. I can just about see Orion from inside the city, every other constellation is drowned out by the horrid blemish of city lights.

  18. Well, think of it this way then: every photon directed into the sky is a photon not helping you see the ground. It’s wasted energy and wasted money. More efficient lighting systems — ones that direct all the light down instead of up — save a lot of money.

    Well, just remember that, even if every photon from the lights were directed at the ground, a good portion of them would then be reflected back to the sky. Of course, if you didn’t lose any light that started “skywards”, then you wouldn’t need as much light/power/electricity/money for the lighting, and the net result would be less light pollution.

    And, while I live in an area where there’s still a pretty decent view of the sky, there’s still plenty of light pollution around, some 50 miles north of New York City. I had forgotten just how much until I was at my cousin’s wedding last year — at a vineyard by the ocean, miles away from the small towns nearby, and many many miles from any big cities — and was amazed at how many more stars (not to mention the Milky Way) were visible.

  19. Calli Arcale

    DennyMo — it’s commonly believed that crime rates are higher with less light, but it’s not actually true. Some crimes are more easily committed under cover of darkness, but the majority of crimes need light just as much as law-abiding activities do. In fact, most robberies don’t happen at night — they happen during the day, when there’s tons of light! (And when people walking around a building don’t look so suspicious.)

    Lights DO help in reducing traffic accidents, though, and that’s very significant. Roads and parking lots will always have to be well illuminated.

  20. minusRusty

    Okay, my question is this:

    How much light is directly jetted out to space, versus how much of it has already been reflected back from the ground?

    After all, if the ground and surroundings don’t bounce back light for our eyes to see, well, then the light isn’t really doing it’s job then, is it?

    I mean, sure, don’t send light directly into space, but there’s still going to be a light-pollution problem so long as we have lights on, right?

    Seriously: How much elimination of wasted light can really happen here?

    -Rusty

  21. Rodney W.

    I don’t live in a big city so the light pollution where I live in the East Bay (CA) isn’t too bad. Although, of course not as good as I remember them from growing up in Tasmania.

    However, part of my walk from the train station each evening is along an unlighted street, so I’ve been using the iPhone App “Distant Suns” (http://itunes.apple.com/us/app/distant-suns-3-unleash-your/id363418936?mt=8) to check star names and constellations.

    I’ve become very familiar with Orion, Taurus, and Gemini (because they are all in the direction I walk home), but daylight savings may throw a monkeywrench in this.

  22. samm

    Pleased to say this has at least been partially recognised here in NZ, while our skies are still relatively dark:
    http://www.tekapotourism.co.nz/feature_archive/starlight_reserve.html

    The Tekapo area is relatively unpopulated even by NZ standards, but I like the idea of preserving the dark sky for the future. Even in our cities we still have darker skies than many northern hemisphere equivalents, something I am grateful for living on the edge of a large urban area-I can do reasonable stargazing from my backyard, but this pales to what I can see by heading a few miles into the countryside. We also have relatively clearer skies down here due to less pollution, and northern hemisphere visitors almost always remark on how many stars are visible compared to where they are from (usually just before noting that the constellations they recognise are upside down).

  23. Scott Calvert

    :: sigh :: This is one of those issues that reminds me just how hard a road we face in doing anything useful about AGW. There is almost no tradeoff here, just a case of eliminating bad design. Almost all light pollution comes from fixtures that let light go up, up and away, not lighting the ground or things on it, doing nothing at all. If we just got rid of all outdoor fixtures that let light go up we’d fix almost all of our light pollution issues.

    Other than bad fixtures, light does go up after being reflected off of ground/objects, and to eliminate that would require dimmer or **different** lighting of things on the ground, but we don’t have to go that far to get most of the benefit. Remember, all that lost light starts as electricity anyway, and we pay for that, dearly.

    Of course, if you want to control reflected light off objects look at the University of Arizona campus. Due to the school being a big time Astronomy and Planetary Sciences school they took light pollution control seriously. All campus lights are low-pressure sodium, which is effective for safety purposes, but is basically a single emission line, so colors look washed out and unnatural. For the astronomers it means almost all the light pollution is at a single wavelength, which still sucks, but it’s much easier to cope with.

  24. Pete

    I completely agree that there’s too much light pollution, which in turn results in a vast amount of wasted energy. There really is no excuse for keeping street lights burning all hours of the night, even for motorways and highways when traffic flow has dropped off.

    I myself have a slightly more serious problem with light pollution in that I don’t get to see a truly dark sky for over three months of the year. Then again I do live next door to the Arctic Circle. ;)

    It gets frustrating during the summer keeping track of the solar wind kicking up and knowing I won’t see another aurora until early October if I’m lucky…

  25. Michael Swanson

    In the otherwise worthless 80′s movie adaptation of “Dragnet” there is one great line. One of the protagonists takes a woman up into the hills above Los Angeles for a date. When he drops the convertible’s roof, she looks up and says, “Look at the stars! There must be dozens of them!”

  26. jfb

    Our neighborhood uses street lights where the lamp is recessed and only directly illuminates a relatively small area under the fixture; there’s no lens to scatter the light in all directions. It’s actually kind of nice; there’s enough light to get around, but not enough to keep you awake if you leave the curtain open (unless you’re the unfortunate soul whose house is right across the street from one). We’re noticably dimmer than other neighborhoods in the area.

    Not that it matters when there’s a football stadium nearby, though.

  27. #13: minusRusty

    I would just invite you to look at Tucson, Arizona and Albuquerque, New Mexico. Both metro areas have very similar size populations but Tucson has a strict lighting ordinance due to all the observatories. I live in Tucson and have spent a lot of time in Albuquerque. The difference between the night sky in the two cities is readily apparent. You can easily see the difference the lighting ordinance makes.

    #10 fetcheer

    We have a super hero working to save our night skies: The Dark Skies Crusader! His adventures are being chronicled on the 365 Days of Astronomy podcast

    http://365daysofastronomy.org/2010/03/21/march-21st-dark-skies-crusader-sheds-light-on-light-pollution/
    http://365daysofastronomy.org/2011/02/07/february-7th-hey-light-get-off-of-my-lawn/
    http://365daysofastronomy.org/2011/03/07/march-7th-globe-at-night-2011/

  28. Number 6

    There was a big controversy over this issue in a semi-rural town near Chicago — Barrington Hills. The fight was spirited with many well-heeled residents dead-set against a proposal by town officials to reduce outdoor light pollution.

    In the end, a watered-down version of the proposed law was passed “making it applicable only to new homes or those homes expanded to more than half of their existing size.”

    http://www.dailyherald.com/article/20110124/news/701249807/

  29. NAW

    @ minusRusty
    That was an issue that happened in my parents’ home town. It is a very small town in the middle of nowhere Texas. Eldorado to be exact (yea that one). But one of the ranches holds a amateur sky watchers deal. For some reason they were complaining on the amount of light pollution a town that small was creating. The town gave in and put some of the redirectors on the street lights, but due to the light colored ground it became noticeably worse. Then the town had to take the things down.

    For where I live, I have an airbase to the north-east and a baseball park to the south. But the sky is still dark enough to see most stuff.

  30. Astrofiend

    Sadly, it simply will not get any better – all of the excellent organisations fighting the increase in light pollution are fighting a losing battle.

    It is a terrible thing, because the powerful connection one feels when seeing the night sky in a TRULY dark area is profound and palpable. It evokes by turns mystery, wonder, calm, fear, amazement, joy, connection, and the list goes on – all the deeply experienced emotions that our modern society acts as a powerful opiate against. All the things that give deep meaning to our personal existence.

  31. non-astro

    I worked with a bunch of astronomers; they were always jetting off to some corner of the world, adding to the skies’ pollution levels more than most citizens. I was shouted down when I suggested a twice-yearly meeting could have one of them held online. Maybe if astronomers cared more about jet fuel pollution, they might get listened to more about light pollution.

  32. E. Manhattan

    When I was a little boy growing up in a small desert town in California, my dad took us kids out in the back yard one dark night and explained we were going to see something wonderful – a tiny artificial moon that the Russians had sent into earth orbit.

    And then – there it was – among the stars a new white pinpoint of light appeared, coming out of the earth’s shadow (as he explained), and as we watched it slowly moved against the stars towards the horizon.

    I haven’t lived where I could see the stars at night for over forty years, and I do miss them! Seeing Sputnik permanently altered my understanding of space and our place in it; I really don’t know how kids who never see a starry night think of the universe they live in.

    Whenever I’m in a part of the world where there is low light pollution (the Australian outback is amazingly dark!) I make sure I have time to go out and sit under the stars, contemplating the night sky and enjoying the sensation of being on a planet.

  33. DrFlimmer

    @ #16 Astrofriend

    Well put! I have not much to add.

    Only the little story, that I’m kind of an idiot. When I was in Namibia last November I had the pleasure of truly dark skies. But, sadly, I didn’t really took the chance of looking at it. I am an idiot!

  34. Erin F.

    My hometown of San Jose already has special lights in the city so Lick Observatory can still do their thing. They’re now testing LED streetlights, which are directional AND brighter. So Lick can still do the wonderful things they do with more ease, but we still get plenty of light to drive/function by.

    I do wish I got the same views at home as when I go camping though. Looking up on a summer night in the Sierra Nevada is breathtaking.

  35. acr228

    @#2 DennyMo

    I’m currently working on a feasibitly study for my technical writing class on the subject of light pollution in the township I live in. An increase in crime is going to be part of it. The International Dark Sky Association had a link to a study done in the UK about how crime rates actually increased in well lit areas because the criminals themselves felt safer. I’ll look around later and see if I can find thatlink again.

  36. San Jose uses low-pressure sodium bulbs which put out a narrow spectrum of light so the astronomers can just drop that from observations. (It’s also a pretty sickly color of yellow.)

  37. Moyer

    For those looking up light pollution is a very big problem, but lets not forget about people like me, the meteorologists in the world whose satellites look back down at the world. The next generation of weather satellites actually take advantage of light pollution and in turn provide us weather people a clearer view of the night sky. So I must admit I have mixed feelings about light pollution.

  38. Grendel

    Not sure about crime rates in other countries, but in Australia the majority of burglaries are carried out in daylight hours rather than after dark, most assaults and serious crimes against the person are committed either by someone you know, or in or near a licensed venue. In any of those circumstances street lighting plays a minimal role. I think it is more about our fear of the dark and what might happen, rather than what will happen.

  39. You can see sky glow from Las Vegas for more than 120 miles. That’s pi*60^2 or over 10,000 square miles of desert where sky darkness is compromised. Is that really necessary?

  40. Carol

    My little town (population 8,000) passed a “Dark Skies Ordinance” five years ago. Lights must be “downcast” and “shielded”. That means the parking lots and streets can still be appropriately lighted but there is no pollution into the night sky. We love our dark sky and fabulous night views in Idaho :-)

  41. HvP

    To me, one of the most annoying astronomy related moments in television occurs during an episode of “Friends.” Ross, the uber-geek of the group, brings everyone up to the roof of their Manhattan apartment building to view a comet through his telescope.

    Uh huh. And as if that wasn’t bad enough, they looked away for a few seconds and missed it go by.

    Sigh…

  42. HvP

    I guess my point is that the above scenario is what most people believe to be a realistic example of night sky observing. If that’s true, then nothing will get better.

  43. HvP

    Oh and…

    *Clap* *Clap* *Clap* *CLAP*
    “Deep in the heaaaart of Texas”

    Sorry, but it’s now just a Pavlovian response.

  44. un malpaso

    Sky glow is REALLY bad in Atlanta too. I have driven 150 miles out of town, easily, and still not found it adequately dark. You really have to get completely out of the East Coast Conurbation to see more than a few of the brightest stars, and it’s sad.

    Bring back the night!

  45. #1 KaneHau writes:
    Move to Hawai’i, we have some of the darkest sky around (especially at 13,769 ft atop of Mauna Kea) aloha!

    Aloha to you too! Never had the pleasure but if I do ever visit Hawaii I’m thinking of going Jimmy Buffet beach bum on the western coast of Kauai, in that gorgeous valley where Jurassic Park was filmed. Is that wrong?

    But seriously, how is the air up there at the top of Mount Kea? Hard to breathe … much? How often do you return to the shore to breathe well? I’ve heard horror stories, but none of the observatory itself. Great telescopes, great place, great people.

    Thanks Phil, for this point. No, it’s not a silly point. My 21 year old son will be 22 when he graduates from Rutgers Biomedical Engg this spring. I mention this because he was a wee infant in diapers when we took him to the local observatory in Hunterdon Co., NJ, about 40 miles west of NYC, when Voyager gave us the first close-ups of Neptune. Good times, seems like yesterday, yet a lifetime to him, yes?

    You couldn’t see the Milky Way there either on a dark night. Light pollution sucks, but what are you going to do about it? Rainbow Six 97% of humanity? Progress happens. If all else fails, visit Death Valley. Or the Australian outback. I’ll take the Valley … less crocodiles. :-)

  46. Gonçalo Aguiar

    I have to wait till summer to get a decent peak at stars and the sky, since i move to countryside in vacation for at least one week. This year I’m bringing my binoculars to have a peak at Andromeda for the first time. I saw it last summer in a URBAN area. (Yes, you can)

  47. Really? I’ve never seen the Andromeda galaxy and I would love to, but I live 30 miles west of NYC, and it’s not like I don’t know how to find it because I do and it involves a small stretch of sky from the lower right bottom of the Cassiopeia “W’. I would love to see it but New Jersey is so happening it’s tough to find a good reason to ever leave, sigh.

  48. AliCali

    @28 Steven Colyer.

    I can see Andromeda Galaxy from Griffith Park, which overlooks downtown Los Angeles, but it’s just a faint fuzzy spot in my telescope. Don’t expect the spectacular picture in your eyepiece or binoculars.

    I find it by starhopping from Pegasus. Here’s exactly how I find it in my head, and I hope it makes sense (you should also check a star atlas).

    There’s the corner star of Pegasus that’s shared with Andromeda. From there, I find the stars of Andromeda. She has three pairs of stars, each further apart as you go away from Pegasus (representing her dress, in my eyes). One row is brighter than the other (I can’t really see the other row from near LA). Go from the bright star that’s second down from Pegasus, jump to the fainter star on the other side of the dress, then go the same distance again in the same direction, and then a little to the right.

    I don’t have a computer on my telescope, so I learn to starhop everywhere, which is quite a challenge in the urban sky. Still, it allows me to grab binoculars and just find Andromeda.

  49. Light pollution is a waste of electricity as well. Light that is going into the sky is not lighting the ground – the intended use of the light.

  50. ccpetersen

    The International Dark-sky Association (Google it) has a lot of good resources on crime rates, statistics, and lighting solutions.

  51. Messier Tidy Upper

    Light pollution is costing us the stars. :-(

    Plus with it something intangible and yet precious, one major part of our connection with the natural world and the people of the past.

    Well said BA – & well said #16. Astrofiend too :

    “Sadly, it simply will not get any better – all of the excellent organisations fighting the increase in light pollution are fighting a losing battle. It is a terrible thing, because the powerful connection one feels when seeing the night sky in a TRULY dark area is profound and palpable. It evokes by turns mystery, wonder, calm, fear, amazement, joy, connection, and the list goes on – all the deeply experienced emotions that our modern society acts as a powerful opiate against. All the things that give deep meaning to our personal existence.”

    I just really hope that you are wrong in your first sentence there astrofiend, because you’re completely spot on correct about the rest of that.

  52. Joe W.

    I have lived near the heart of Orlando, Florida for nearly my whole life, and I never have gotten the chance to see the Milky Way in its true glory. It’s a shame, especially with all the abominable humidity that adds fuel to the fire… :(

    I really hope we can direct the light better in the future. No one should be disconnected with the Universe.

  53. Messier Tidy Upper

    @ 28. Steven Colyer & 29. AliCali :

    There’s the corner star of Pegasus that’s shared with Andromeda.

    That would be Sirrah or Alpheratz (Alpha Andromedae) :

    http://stars.astro.illinois.edu/sow/alpheratz.html

    Which is a hot type B8 IV blue sub-giant and mercury-manganese star as well as a spectroscopic binary.It marks the start of the back leg of the flying horse with the top of the front leg/ body being the bright red giant Scheat, the neck-shoulder join being the blue dwarf star Markab (Alpha Pegasi) and the body-tail juncture the B2 dwarf star Algenib. (Gamma Pegasi.)

    See Kaler’s stars :

    http://stars.astro.illinois.edu/sow/pegsq-t.html

    http://stars.astro.illinois.edu/sow/and-t.html

    for a couple of handy photo-maps that help locating things in that constellation and others too.

    Incidentally, counting the number of stars inside the square of Pegasus is a good test of how light polluted or otherwise your skies are – the more stars inside the square you can count the better! :-)

    Hope this is helpful / interesting for you. :-)

  54. Paddy

    I heard an apocryphal anecdote once about a group of inner-city schoolkids taken out camping, who asked what the lights in the sky were.

  55. malendras

    Light pollution is a very big problem where I live, specifically, right in New York City. I went to Yellowstone a few years ago and I couldn’t believe mow many more stars I saw. I can’t recall having actually ever seen the Milky Way, even out there. And from what I’m reading, it’d take a 150 mile trip outside all city limits to get a good view.

  56. bad Jim

    (Had to drag out my map of Berlin. It looks like Alexander Platz is the big offender off to the right. Kürfurstendamm and the Sony Center at Potsdamer Platz aren’t as bad as I expected.)

    One summer night, at an office party in Costa Mesa, I found myself giving my co-workers a basic astronomic orientation when only a few first-magnitude stars were visible. I can’t decide which was worse, the poor visibility or the fact that none of them had the least familiarity with the sky.

    People don’t look up.

    Last Wednesday I was so thrilled by the sight of Mercury and Jupiter glowing brightly over the western horizon that I called my brother in Maui to tell him to go out and look the next night. The following evening, during a family gathering, with clouds massing on the horizon, I kept checking the sky after sunset for the first possibly glimpse. When I could reliably discern both planets in the twilight I collared my nephew and niece, hustled them outside and showed them where to look. They couldn’t make out anything. Doubting my sanity I asked their father, my other brother, to see for himself. He could, but then he’d seen Mercury before and wasn’t exactly thrilled. He noted that there was a knack to spotting an object in twilight. By the time it was dark both planets were hidden in the marine murk.

  57. Sieben Stern

    The skies at night, are too darn bright
    and the rent is too damn high

    *singing*

    @bad jim – i think i’m one of the last people around here that bothers to look up anymore :/

  58. Nigel Depledge

    MinusRusty (12) said:

    Okay, my question is this:

    How much light is directly jetted out to space, versus how much of it has already been reflected back from the ground?

    After all, if the ground and surroundings don’t bounce back light for our eyes to see, well, then the light isn’t really doing it’s job then, is it?

    I mean, sure, don’t send light directly into space, but there’s still going to be a light-pollution problem so long as we have lights on, right?

    Seriously: How much elimination of wasted light can really happen here?

    It depends on several things, among which are:

    1. The design of the lights. Some lights already direct about 80 – 90 % of their light towards the ground, so the saving for these would be small. Other lights (e.g. globe lights on top of a pole, which seem common in town centres in the UK) direct at least half of their light upwards, which strikes me as insane. For lights such as these, a reflective cowl would allow you to halve the power of the light and still have the same amount of light hitting the pavement.

    2. Bandwidth of the light. Low-pressure sodium lamps (the orange ones) make nearly monochromatic light, which is pretty easy to filter out and impinges less on wildlife. Medium- and high- pressure sodium lamps (respectively the slightly pinky-coloured and white streetlights) and other types of lamps (such as halogen floodlights) generate a broad spectrum of light that works better for our eyes but has a greater impact on wildlife and also is more polluting.

    I’m sure there are other factors (such as the kinds of surfaces on which the light falls, the spacing of the lights, and so on), but ensuring that all of your light leaves the lamps in a downwards direction can probably save about 20 – 30 % of the energy used and make no difference to how bright the streets are. The reduction in light pollution may be more than this, because no surface reflects light with 100% efficiency so the light that is directed upwards at present will have a greater contribution to light pollution than the ligth that is currently directed downwards.

  59. I came home this weekend at about 2 in the morning and I noticed that blackbirds were singing. I also can tell easily which direction the harbour (I live in Hamburg) is in on any cloudy night from the orange glow. At least I can watching meteor showers sitting in the park and the Milky Way was visible, if very faint, so all is not lost.
    But the sky over the Nevada desert, over Yellowstone and over Normandy (where I first saw the Milky Way as a child) make it very clear how much I miss out on.

  60. Bramblyspam

    Mating cycles? Hunters and hunted? Seriously, where this causes problems, evolution will lead to a new, stable balance in short order. There’s nothing inherently superior about an ecosystem with darker nights, even if astronomers would prefer it.

    There’s also nothing inherently superior about stargazing, as compared with reading a book or surfing the web, no matter what astronomers prefer.

    I’m all for more efficient lighting and saving energy, and I do appreciate a good view of the stars at night, but let’s not get carried away here. Light pollution is not going to cause mass extinctions; the whole “nature” portion of your argument strikes me as a weak, kludgy rationalization tacked on in the belief that it supports your personal desire for darker nights.

  61. Uite

    Living in South Holland, light pollution here is horrible; it’s some of the worst in the world. Seriously, I have trouble eyeballing magnitude 2 stars, and that’s when conditions are good!

    I remember one time, I was in the woods on clear night with a full moon. Things were pretty bright and given that I have good night vision, I could easily find my way around, even without extra light. However, sometime after midnight, clouds rolled in and suddenly everything was awash with light. If not for that ugly sodium-yellow colour, and the fact that it was smack-dab in the middle of the night, it could easily have been confused for daybreak!

  62. Nigel Depledge

    Grendel (20) said:

    Not sure about crime rates in other countries, but in Australia the majority of burglaries are carried out in daylight hours rather than after dark, most assaults and serious crimes against the person are committed either by someone you know, or in or near a licensed venue. In any of those circumstances street lighting plays a minimal role. I think it is more about our fear of the dark and what might happen, rather than what will happen.

    You may well be right here, and I think someone else mafde a very similar point somewhere up the thread.

    However, does this situation exist because of all the streetlighting we have, or in spite of it?

  63. #38, 41 Nigel:
    Apart from the fact that most crime happens in daylight, there are actually some kinds of lighting which can potentially make nighttime crime worse! You mentioned globe lights, which are commonly used in the UK to illuminate car parks and footpaths. A globe light emits light from all of its surface, except for a small circle at its base, where it’s attached to the pole; the result is that there is a cone of darkness below it. I once saw John Mason give a talk on light pollution, in which he showed a photo which illustrated this perfectly; below the light, there was a circular patch of ground of a couple of feet radius, centred on the pole, which was in inky black shadow. A mugger could simply stand in that circle, and his victim could pass by within a few feet and not see him, this allowing him to attack them from behind.

  64. Sadly, communicating this to the public is often like banging your head against a brick wall. Many people get the misconception into their heads that “astronomers want to get rid of streetlights”, and nothing will convince them otherwise.
    Back in 1990, a UK Dark Skies campaign was launched during that year’s National Astronomy Week. During that week, my local astronomical society had a display in a shopping mall, where among other things, we tried to make people aware of the light pollution problem. Knowing full well that most people wouldn’t care about astronomy, we emphasised the “wasted light equals wasted energy equals wasted taxpayers’ money” argument.
    While I was manning the stand, one guy saw the leaflets, and asked me what it was about. So I told him all about it, putting a lot of emphasis on the wasted money aspect, and made it absolutely clear – or so I thought – that we didn’t want to get rid of streetlights, but wanted them to illuminate the ground and not the sky. I remember it as if it was yesterday; I can even remember some of the exact words I said to him: “If streetlights were properly shielded, they would provide the same level of illumination on the ground, for half the cost!”
    He replied, “But then how would we see where we were going?”
    Head, meet wall!!!

  65. Kevin

    @Bramblyspam

    If you don’t care about the stargazers and the animals I suggest you Google “light pollution and cancer” – numerous studies seem to indicate that reducing light pollution is good for YOUR health and well-being, too.

  66. Kaylen

    I live in an area with a ton of subdivisions closely packed together. We probably have thousands of street lights illuminating the streets all night for no one. I wish that there could be motion sensors so only the lights you need would be on. It just seems like such a waste.

  67. Michael Swanson

    @60. Bramblyspam

    “Seriously, where this causes problems, evolution will lead to a new, stable balance in short order. There’s nothing inherently superior about an ecosystem with darker nights, even if astronomers would prefer it.”

    You realize that evolution works slowly, right? Very, very slowly.

    Just admit that you don’t care. It’s more concise.

  68. Bramblyspam

    @Kevin (65): I just googled “light pollution and cancer”, and while I’ll readily admit that I didn’t exactly do an exhaustive survey of the literature, what I found looked like junk science at its finest.

    At most, you have correlation, and correlation =/= causation. My favorite example of this: ice cream consumption is correlated with rapes. Of course, this doesn’t mean that eating ice cream turns people into rapists. What’s really going on is that ice cream consumption and incidences of rape both increase with warmer weather.

    There may well be more cancer in areas with more light pollution, but methinks that’s most likely because areas with light pollution are more heavily industrialized, and industrialized areas have other factors that increase cancer rates. It’s possible to design a study that properly tests the light –> cancer hypothesis, but the articles I saw certainly didn’t give me the impression that the conclusions came from such studies.

    I have a layman’s understanding of cancer. The notion that bright night skies are a significant factor in causing cancer strikes me as tenuous at best, so it would take a very rigorously designed & executed study to convince me that there indeed is a significant causal relationship.

    @Michael Swanson (66): Yes, for the most part I don’t care, because I simply don’t think light pollution is a problem – but let me add that you underestimate the speed of evolution. The greater the stress on the ecosystem, the more rapidly evolution works, especially in short-lived organisms. One of the better known examples is peppered moth evolution.

  69. I would strongly recommend everyone check out the Illinois Coalition for Responsible Outdoor Lighting at http://illinoislighting.org/ , as they touch on more bases that just dark skies, and show that there are reasons for people besides astronomers to be concerned about stray light. They also have a section of suggested and common sense solutions to further advance responsible lighting practices. Unfortunately, the term “light pollution” has been widely correlated to only an issue for the small special-interest of astronomers, but, as you said Phil, its time we start educating the public and governments that it is a problem for everyone.

  70. Kevin

    @Bramblyspam (#67)While you will certainly find lots of mere blog entries, you also readily admit that you didn’t “exactly do an exhaustive survey of the literature.” Had you done so you would have found links to studies and/or news items that support what I pointed out. The American Medical Association, National Institutes of Health, University of Maryland Medical Center, and many more have chimed in on the subject.

    If you had bothered to dig a little deeper still, you’d learn how excess light at night leads to decreased levels of melatonin production and that subjects in several studies who lived in light polluted areas seem to have higher incidences of breast or prostate cancers than those who live in areas that are not light polluted (night workers are also affected).

    To make it a little easier for you, here’s a link to the wiki article on light pollution and the subheading on health – follow the links in the references . . .

    http://en.wikipedia.org/wiki/Light_pollution#Effects_on_animal_and_human_health_and_psychology

    There are also links at the International Dark Sky Association’s site:

    http://www.darksky.org/mc/page.do?sitePageId=62906#HumanHealth

    I’m a layman on the subject, too, but I learned how to read a LONG time ago. I’d be more skeptical if it were limited to one study, but, as you can see (if you choose to take the time), it’s not.

  71. Josie

    Someone took freshman biology…
    “One of the better known examples is peppered moth evolution”

    There is a huge difference between changing ones spots…or whatever pigment you like, and changing basic metabolic functions or behavior. It’s a lot slower and the mechanisms involved are more complex than allelic frequency shift.

  72. icemith

    Is anybody actually appreciating the maths relating to the light pollution/reflection problem. It seems the common idea is that light either is directed at the ground or it is directed straight up into Space. Nothing really about the reflected light off other things such as buildings, (that is, those without appreciable internal light from their windows), or for that matter, the actual color of the surface to be reflected off. The light radiating from even shielded lamps, does so at angles lighting objects, paths and buildings within a reasonable range. They all reflect light at various angles too. Moisture, smoke and exhaust gases from not only motor vehicles, but air-con heat exchangers etc., contribute to the overall light pollution problem

    Surely our Paint and Pigment people can provide us with a less reflective surface that does indicate what is there, (hopefully tasteful), but I do not hold out much hope for the Neon Sign and other Advertising signs people. Some streets are painful to the eyes, with the gross overload of lighting in those high trafficked areas in our cities, and I’m sure that factor alone leads to increases in accidents as well. The other areas of intense light are the Sport fields and Arenas for night games, they used to be perfectly OK in the daytime once! I haven’t heard if there are any regular “after-midnight games”, but no doubt that will come too.

    I think that anybody who seriously believes, or hopes, to be able to achieve good “seeing” in the city, is surely deluded. I have long abandoned any hope of being able to set-up in the backyard, and expect the same kind of dark sky as I have appreciated out in the “Outback” of Australia.

    Bye the way, the assertion that the Outback is crocodile infested is totally wrong (Steven Colyer #45). Sorry Steven. Yes, in the tropical north, in the coastal areas there are crocs, but there are vast areas of the rest of the country, with dozens of established sites, far from city lights, catering to the keen Astronomer. And not a crocodile at all. Nor alligator, or for that matter, definitely no rattle-snakes or side-winders!

    Ivan.

  73. Quiet Desperation

    I dunno… cities can be so pretty at night. Look, the population is supposedly trending toward urbanization, so with more people concentrating in cities, there will be ever more good dark sky locations away from them. And sweet, sweet, cheap land for my retirement as fraking far away from a major city as I can get. :-P

    the picture above was taken at night, to give you an idea of how bad this is

    Am I the *only* one here who wants to know the shutter speed of that image?

  74. Great article as usual, Phil. Thanks, Thad, for mentioning GLOBE at Night.

    For anyone not familiar with GLOBE at Night, it an international citizen-science campaign to raise public awareness of the impact of light pollution by encouraging everyone everywhere to measure local levels of night sky brightness and contribute observations either by smart phone, tablet or computer to a world map. All it takes is a few minutes to participate at http://www.globeatnight.org. By recording more measurements of the night sky brightness levels in neighborhoods, people are using this information in local decisions on how to increase safety, lower energy consumption, and protect human health and wildlife — areas affected by high levels of extraneous light. These observations will also help identify parks suitable for urban “sky oases”- places that can be developed to help city dwellers appreciate the night sky from a safe, dark place.

  75. PS. The GLOBE at Night campaign starts tonight, March 22 and goes through April 4 in the northern hemisphere and starts March 24 and goes through April 6 in the southern hemisphere. Hope you will join us. Your observations will make a world of difference. (www.globeatnight.org)

  76. Harley

    I’m lucky enough to live in a light pollution free area in Texas so I can shoot cool milky way time lapse videos like this one: http://www.youtube.com/watch?v=XANnv5SfxPg

  77. AliCali

    @ Bramblyspam (60)

    “…where this causes problems, evolution will lead to a new, stable balance in short order.”

    Although I’m not a biologist, my understanding is that some species will evolve, while others just go extinct. There have been many species that went extinct from the expanded territories of humans; they could not evolve. (I have a book that lists examples, if you’d like me to dig it up.)

    So your logic seems to indicate that any species that cannot handle our light pollution will die, and tough luck for them. We will not change our habits, however wasteful, just to save some species from going extinct.

    Or am I misreading your comment?

  78. Bramblyspam

    @Josie (68): Are you asserting that the jolt to the ecosystem from light pollution is somehow more severe than the jolt faced by peppered moths? I seriously doubt it. I don’t see why allelic frequency shift wouldn’t suffice to make the necessary adjustments. (Keep in mind, we’re talking *only* about the effects of light here, ignoring other changes caused by urbanization). While it’s good and proper to be concerned about nature, nature is a lot more robust than many people give it credit for being.

    Energy efficiency is a good thing, but the bottom line is that cities are bright because people want them that way, for good reasons. Astronomers do need to accept that most people aren’t astronomers, and their reasons for preferring light are no less important than an astronomer’s reasons for preferring darkness.

    Having said that, let me emphasize again that if we can achieve the desired ground-level lighting at lower cost, I’m all for it.

    @AliCali (71): We live in a dynamic world, not a static one. Things are constantly changing, species go extinct and new species evolve all the time. My view is that nature is *always* in balance – if things change, then you just have a different balance.

    There is such a thing as catastrophic collapse, e.g. when easter islanders chopped down all the trees on their island. Other things being equal, a balanced ecosystem with lots of diverse life is preferable to a balanced ecosystem with less life and fewer species. However, we’re not talking about changes on the order of chopping down all the forests. We’re talking about changes on the order of having a full moon every night, rather than once a month. I just don’t see light pollution as being a big enough jolt to have catastrophic effects on entire ecosystems.

    If you go ten miles outside a city at night, it’s still pretty darn dark outside, even if you can’t see the stars as well as you could in the Australian outback.

  79. GrogInOhio

    @54 Paddy…

    True story… as a teen I was sent off to a residential school out in the country for “gifted” children (the alum always put “gifted” in quotes… inside joke). One of the girls from the inner city actually started crying and was frightened by “too many stars up there!”.

  80. AliCali

    @Bramblyspam (72)

    “I just don’t see light pollution as being a big enough jolt to have catastrophic effects on entire ecosystems.”

    So the question is what degree does light pollution have on the ecosystem? I’m actually not sure how that’s quantified. If it’s only cockroaches not scurrying outside as often, I’m sure they’ll survive. If it’s nocturnal animals not being able to hunt and thus have their numbers dwindle, that’s something else. Where’s the tipping point?

    I suppose the next step is to actually read the studies to see their data, assumptions, interpretations, and analysis. Maybe after tax season.

  81. Bk

    Even if light pollution (a bit harsh, no?) have an impact on some ecosystems, which it probably does in some way. its gonna need to have significant impact. We dont have all this light turned on for fun. Just because most of us go to bed at night does not mean that our entire society stops.

    i’d like to really see the sky sometimes, but as you already guessed, im not really the outdoorsy type, i need proper civilization to thrive. Where ever i go there is electricity and street lighting of variating degrees. To see one of the swirly arms of our galaxy is on my to do list, but its not going anywhere is it?

  82. ecodude

    Regarding light pollution and cancer:

    The connection between light pollution and cancer comes from the disruption of melatonin production. Screwing up melatonin screws up your circadian rhythm, and this may contribute to some cancers (breast, prostate). Breast cancer is correlated with light at night, while lung cancer isn’t – still not a proof, but slightly better than simply a correlation study. (see http://www.ncbi.nlm.nih.gov/pubmed/18293150 )

    Regarding light pollution and ecology:

    It’s not as simple as saying creature will adapt. To take a specific example, zooplankton feed on phytoplankton, but they are eaten by fish that visually track them. So in a natural environment when it’s really dark they rise to the surface and gorge, and then swim back to the bottom as day breaks. They cannot simply evolve to come up when it’s brighter, because there is a competing pressure (fish) that prevents them from doing this. So light pollution contributes to algal blooms in urban and suburban lakes, and there’s no easy evolutionary trick around this (other than all the fish dying, perhaps…).

  83. AliCali

    @Bk (75)

    I think you missed the point. Nobody wants the lights off. They just want the lights to go only downward and light what’s intended. Here are the advantages:

    1. Better lit areas (what everyone wants)

    2. Use less electricity (save money)

    3. Longer-lasting light bulbs (save money on bulbs and installation costs)

    Where’s the argument? Even without the issues of the dark skies and possible ecosystem damage, why would anyone not want this? The only drawback is some upfront costs for better bulbs and possible covers, which is paid for rather quickly in the savings above.

    Basically, it just takes initiative. Astronomers lead the charge, because they are the ones who notice lit skies first. But in reality, this is just a good idea, and saves money.

    I’m in the San Fernando Valley, and they are slowly changing out the yellow bulbs with white LED lights. The streets are much better lit, the bulbs won’t need to be changed nearly as often, and much less light goes to the sky. I know because when I fly into Burank at night, we go right over the valley, and I can tell which neighborhoods have the new lights and which have the old ones. On the new ones, I can only see the street. On the old ones, I can barely see the street because there’s a bright light shining directly at me.

  84. Naomi

    Scott @ 23, agreed! I did a semester on exchange at UA (that Mars class is AMAZING), and that included an evening class – I was amazed at how much of the sky I could still see every evening when I left, even on campus. (Of course, it was even more striking out where I was staying, near the outskirts of Tucson. I was a three-minute walk from Speedway and I could still get clear-enough skies to make out the Orion Nebula, Saturn, and a couple of meteor showers. I have NEVER been able to see those at home!) I swear, one night when I was walking home, it was a new moon and my primary illumination was VENUS. It was that bright. (Of course, it did mean I had to find my way with a flashlight. The joys of having to walk down a wash to get home…)

    Of course, those campus lights do hum like crazy.

    Now I’m back home in suburban Sydney, and the light pollution is significantly worse. But at least I’m not in the CBD – looking up at the Southern Cross, you can no longer see Epsilon, and Delta is starting to fade out too. This is the constellation that’s ON OUR FLAG.

  85. Bobby

    I remember how I first read about how lights should point downwards. Then I looked outside. In my lovely Eastern European homeland (Bulgaria) the vast majority of streetlights are indeed pointed downwards with reflective cover on top and on the sides. This should really be the norm – it’s quite effective – you get to see the brighter stars constellations with no visual aid. Especially after midnight. But you still need to get out of the city if you want a good view of the Milky way, for instance.

  86. zandperl

    Any thoughts about radio-dark skies? Part of AT&T’s motivation for buying T-Mobile was the “need” for a larger chunk of the electromagnetic spectrum. As the cellphone lobby convinces the US and other governments to open up more and more of the microwave/sub-mm spectrum to commercial use, that means less and less of the spectrum is available to observe astronomy targets.

  87. Bryan Feir

    I remember, many years ago, visiting the Dominion Astrophysical Observatory just north of Victoria, B.C. The observatory is sitting on the opposite side of a mountain from the city proper, over Prospect Lake. Even then, back in the early 1980s, they said they could point the telescope straight up and calibrate the spectroscope by the mercury vapour lines from the city reflected off the water vapour in the air.

    This became a big issue here in Toronto a few years back. Both the David Dunlop Observatory and the Observatory at York University were rendered nearly useless thanks to a big Coliseum movie theatre up in Vaughn which has moving spotlights shining up into the clouds to attract attention.

    zandperl@79:
    Regarding radio-dark skies, well, there’s a reason why the Algonquin Radio Observatory in Canada is smack in the middle of one of the biggest areas of parkland in the country: the only radio sources you really have to worry about are the ones from satellites.

  88. Russ

    In the Chicago area on Illinois route 53, the state has been putting in new lights for the last 10 years or so. These lights shine down. You can tell the difference between these and the older lights as there is no glare associated with them.

  89. katwagner

    #40 Carol are you in Ketchum? Because out here in rural Blaine County the Dark Skies ordinance applies only to new homes (new since when, I don’t know). I’d really like for them (someone!) to enforce the “full cutoff” at the property line because our neighbor across the field has a huge spot that lights up our bedroom and three miles down the road, there’s a yellow light on all night that lights up our other bedroom. And I don’t want to put curtains up – we were here first. But I agree, downcast lighting in Ketchum is a start.

  90. Carol

    Katwagner, I’m in Hailey which also has a dark skies ordinance very similar to Ketchum. Quite an impact to have your neighbor’s light affect you – especially into your bedroom. We are lucky to have Dr. Steve Pauley (in Sun Valley) be such an advocate for dark skies in Blaine County. Dr. Pauley just sent out an e-mail about the effect of light at night and health issues which sure seems to pertain to your situation. I’m guessing you’ve called the County planner, Tom Bergin to ask for enforcement? Might also be worth a call to Dr. Pauley to ask for help. Good luck!

  91. katwagner

    @82 Carol. I love Dr. Pauley! And we are clear out Glendale and the yellow light is down in the flats. So I’ll call Dr. Pauley and I’ll call P&Z and talk to Tom.

    Eeek! Small world. A few years back I told Dr. Pauley about a big ole meteor – serious fireball – I saw one night and no one else in the county saw it and he said that happened to him up at Galena Summit in the middle of the night. Wow!

  92. icemith

    @77. Naomi, Hi.

    Yeah, I can concur on the gradual disappearance of poor old Epsilon from Crux. It used to be some kind of benchmark as to how much gunk/water-vapor there was in the air, well here in Sydney anyway. Certainly have to convince yourself it is still there, just by looking at where it should be, without any aid. My “three score and ten” eyes may have something to do with it, as my glasses do not help one iota, in fact I can see the pinpoints of starlight somewhat better without the glasses!

    But I wonder why the NZers officially have no Epsilon on their flag. Did the designer have a poor viewing night when he was looking for inspiration and saw the Southern Cross, missing the fifth star because …… oh yeah, New Zealand is not referred to as “The Land of the Long White Cloud”, for nothing! That and volcanoes and those Shaky Things wouldn’t help.

    Ivan.

  93. Nigel Depledge

    Josie (68) said:

    There is a huge difference between changing ones spots…or whatever pigment you like, and changing basic metabolic functions or behavior. It’s a lot slower and the mechanisms involved are more complex than allelic frequency shift.

    Yes, this. To add to this, changes in the frequency of already-extant alleles in a polymorphic population is a different thing altogether from the evoluiton of a new metabolic path. Now, it is remotely possible that new metabolism could evolve quickly, if the necessary mutation happened at just the right time, but it is more likely to occur through slow changes, using enzyme specificities that already exist (very few enzymes are specific to just one substrate or to just one reaction, but many are efficient with just one reaction and just a few substrates). All that is required for shifts in metabolism is adjustments to the efficiencies of the relevant enzymes.

    A similar principle applies to behaviours. Rapid change is possible, but gradual change is more likely.

  94. Nigel Depledge

    Icesmith (69) said:

    Surely our Paint and Pigment people can provide us with a less reflective surface that does indicate what is there, (hopefully tasteful), but I do not hold out much hope for the Neon Sign and other Advertising signs people. Some streets are painful to the eyes, with the gross overload of lighting in those high trafficked areas in our cities, and I’m sure that factor alone leads to increases in accidents as well. The other areas of intense light are the Sport fields and Arenas for night games, they used to be perfectly OK in the daytime once! I haven’t heard if there are any regular “after-midnight games”, but no doubt that will come too.

    This is a tricky one. The less reflective are the surfaces in an urban environment, the harder it will be for people to see those surfaces at night. Which kinda defeats the object of street-lighting.

    I think the best anyone can hope for is to reduce light pollution by some proportion or at least prevent it from increasing any further. Eliminating light pollution would mean eliminating the outdoor use of lights at night.

  95. Bramblyspam

    @Nigel Depledge (85): I’m reminded of this quote by Larry Niven: “As for AIDS, it’s a plague. We are human, we get plagues. They come along every so often, kill off two thirds of the population; in the next generation it’s a quarter; after that it’s a childhood disease.”

    For most any shock that falls short of dino-killing asteroids on the killer scale, there will be some percentage of the population that has what it takes to handle it – and that percentage will reproduce, while the rest won’t. It’s the same with people as with peppered moths. No instant mutation is needed.

  96. Bill3

    I was thinking about this one on my way to work again this morning and I tried to examine every light source I saw for anything pointing up or wasting light upwards – and it dawned on me – most light sources do direct their light down or onto the intended surfaces. The kicker is that light shining in the right direction isn’t what makes something visible, it’s the reflection of that light.

    I’d wager that the great majority of “wasted light” is from reflections off the surface. Look at the city map above – most of the wasted light is a network of roads, all with their lights shining down, illuminating the road surface, obviously for safety and visibility. But the satellite sees it too because a good deal of the light reflects back upwards too. And pilots use this light as well for reference, so even if we could somehow make it not reflect upward, it would cause more problems than it solves.

    I don’t think there’s a good solution to this one – astronomers are going to have to keep seeking dark areas for their observations. It’s not like we live on Coruscant or anything. :)

  97. Nigel Depledge

    Brmablyspam (96) said:

    For most any shock that falls short of dino-killing asteroids on the killer scale, there will be some percentage of the population that has what it takes to handle it – and that percentage will reproduce, while the rest won’t.

    Not necessarily.

    If a particular behaviour or metabolic tweak simply doesn’t exist in a population, and yet that trait is needed to survive a change in the environment, then the whole population will die.

    Your analogy to plagues etc. is of limited validity.

  98. Aubri

    @Bill3:
    I was in Hawaii this past week, so I’ve had ‘dark sky’ on my mind lately.
    I arrived on the Big Island shortly after sunset, and the first thing that I noticed after exiting the airport and leaving Kona was that the distant city lights were remarkably dim. For those who haven’t been there, the entire island is under a dark sky initiative for the benefit of the telescopes; all the street lights are bright yellow sodium vapor jobs, so that the telescopes can simply filter out the sodium spectrum to account for sky glow, and the human eye reacts most strongly to yellow and green light, so yellow lights give you the most subjective illumination per photon. Outside of cities, they use retroreflectors to mark road edges instead of street lights except at intersections. It’s honestly a little eerie to a Texas boy like me, to have an unlit highway appearing in my headlights, leading to a city marked by nothing but a speckling of yellow!
    I live in the Dallas/Fort Worth metroplex, one of the brightest areas in the US, so it was really amazing to me both how dark a large city could actually be, and how little effort it honestly took to darken the island. From our rented house near Waimea, I could make out the Milky Way without even waiting for my eyes to adapt to the dark! (Of course I made time to visit the Onizuka Center on Mauna Kea, though sadly it was a gibbous moon that night.) The observatories are now lobbying the rest of the islands to implement the same dark-sky initiatives.
    While it would cost a city quite a bit to immediately replace all their streetlights and so forth, this is the sort of initiative that could be put in place now to install dark-sky lights as existing equipment wears out. I was already a bit of a dark-sky crusader to begin with, but I didn’t really have a sense of how effective these kinds of measures could be. Before, I had a sense of “yeah, it’d be nice, but how much good could it really do in a major city like this?” Hawaii shows what can be done.
    Maybe if you don’t live within a hundred miles of a major telescope, you don’t need to be quite as zealous about light pollution — but when my airliner made its approach to LAX on the way back, it kinda drove the point home. I could clearly make out parking lots and buildings from several thousand feet in the air. There’s no need for that.

  99. @#89. Russ:
    While some select roads in our area have improved lighting, it is an unfortunate majority that still have older, non-shielded fixtures. Even worse, you may have noticed that many of the more “affluent” neighborhoods (Naperville, Glen Ellyn, ect) have chosen to recently install vanity light fixture designs. For example: http://illinoislighting.org/fixture3.html

    Drive down Roosevelt Rd. through Glen Ellyn (which intersects RT 53) and you’ll notice turn-of-the-century style coach lights along the road, with dual lamps lighting the streets AND sidewalks! These municipalities choose the vanity lighting based on how they appear during the day, without any consideration for their night-time disfunctionality. It is often the lighting-industry contractors who push these more expensive and less efficient products on the unknowledgeable city chamber members, who approve them because they “look pretty.”

  100. AaronH

    A great documentary on this topic was just premiered at SXSW: The City Dark. It makes a compelling case for curbing light pollution for audiences of non-astronomers.

    http://www.thecitydark.com/

  101. Sydney

    Want to learn more about light pollution? Check out Internationl Dark Sky Association! http://www.darksky.org :)

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