A couple of months ago, someone in Cloudy Night's Light-Pollution Forum wondered what's the most light-polluted city on Earth. I guessed that it was somewhere in Asia. A different person said that he was sure that North America headed the list. To make a long story short, I was dead wrong and he was absolutely correct.

It occurred to me that if you measure "most light-polluted" by the area where the Milky Way is difficult or impossible to see, then the Light-Pollution Atlas could provide an objective answer. All I had to do was count the number of red and white squares within each metropolitan area, correct for the fact that places at high latitudes are stretched horizontally, and I would be done.

These are four of the most densely populated areas in the world, each measuring about 350 by 300 miles. Their light-pollution patterns could hardly be more different!

Tony Flanders

There are a few caveats. As I said in a recent blog, it's unclear how accurately the Light Pollution Atlas captures actual conditions on the ground. Also, many big cities are on seacoasts, and it was tricky to separate the white line representing the coastline from the white for light pollution. Finally, it's quite possible that the methodology behind the Light Pollution Atlas has some kind of regional bias. But it's hard to believe that any such bias could be big enough to explain the differences that I found.

Nine of the top ten light-polluting metropolitan areas are in North America. Sorting by white squares (rather than red and white combined), Tokyo just slides onto the list in the #10 spot. But Tokyo is by far the world's most populous metropolitan area, almost equal to New York and L.A. combined. No city in Europe even makes the top 20.

It's not surprising that cities in the less developed world don't make the list. Beijing, Shanghai, Delhi, Mumbai, and Kolkatta each have light-pollution blobs comparable to a U.S. city of two million, though each of those metropolises have roughly ten times that number of people. But in these parts of the world, energy is far more expensive relative to income, and people don't splash it around heedlessly. Moreover, most of the 120 million or so people living in the map quadrant at lower left are in villages that have essentially no outdoor lighting at all.

But Europe and Japan have standards of living comparable to the U.S. I estimate that the U.S quadrant is home to about 50 million, the European quadrant to about 80 million, and the Japanese quadrant to about 90 million. Yet according to this map, the amount of light pollution in Europe and Japan is far less than in the U.S. Why is this true? Can those areas be a model for better lighting practice in the U.S.? I'll explore those subjects in a future blog. Meanwhile, I would love to hear comments from people with on-the-ground astronomy experience both in the northeastern U.S. and in Japan and/or northwestern Europe.


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June 28, 2009 at 9:12 am

I know for certain that you are not able to see the milky way in most parts of germany... Its even very difficult to see it when you are on the country side. In the cities it is completly impossible.

greetings, Tom

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June 28, 2009 at 9:53 am

I live in Oostende (Belgium, the orange blob above Paris). Visual limiting magnitude is 2.5. From my front door is can count 37 bright street lights. There are many lights shining upward to illuminate buildings. There's even illumination along the beach. If I want to see te Milky Way I have to drive 270 km to the south. In the northern 3/4 of Belgium there is light pollution everywhere. Overall the light pollution in Belgiüm may not be as intense as around New York or Tokyo, but it's everywhere.

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June 28, 2009 at 11:38 am

Tulsa, Oklahoma is pretty bad if you're downtown. Luckily you can generally drive 30 minutes any direction and have pristine skies on a good night!

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Mike Hermsen

June 28, 2009 at 7:30 pm

It is amazing at just how many younger people have never seen the Milky Way when asked. I count myself fortunate to have seen it so many times when I was younger. It is a harder thing to see with all of the light pollution now.

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Colorado Springs

June 28, 2009 at 9:22 pm

I see that political correctness has planted itself firmly into the "Sky and Telescope" community. Light pollution, as you call it, is a direct reflection of western prosperity. I'm thoroughly sick and tired of "westerners" apologizing for their prosperity. Any person in the second or third world would love to trade places with any of you guilt-ridden, enviro-hypocrites so you can taste the splendor of living in a culture that doesn't have "light pollution". One of the results of this polluted thinking is the "Cap and Tax" bill that just passed the United States House of Representative two days ago (Friday, June 26th) This tax will make us less prosperous, thus we'll be "polluting" less light. I say thank God for "light pollution". Man-made light is a great thing, and the rest of the world wants more of it, not less.

Thanks guys, you just made the world a poorer place.

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August 16, 2020 at 1:59 am

This statement is beyond ignorant for a variety of reasons:
- First, recognizing environmental issues and having the capacity to solve them is proof of our prosperity. Many underdeveloped countries have absolutely no ability to solve the problems we create (pollution, privatization of water, etc.), yet we do. Shouldn't that make us richer if we were able to solve the problems our increasing wealth created?
- Second, you are forgetting that light pollution hinders astronomers, whether amateur or professional alike, from making observations and furthering scientific advancement.
- Third, you do not realize how easy it is to fight light pollution. You do not have to make "the world a poorer place" in the process; actually, you could increase spending money drastically by investing in properly-insulated and deep-colored (red, deep-orange, etc.) lights that are extremely energy efficient and cost very little to maintain. This will decrease taxes for public lighting and lighting costs for homes and buildings. That alone will decrease the magnitude of our cities x5.
- Fourth, lastly, light pollution does not at all reflect western prosperity. Flagstaff, an American city, is internationally recognized because as a city/metro area of over 100,000 people, the city center still has beautiful views of the Milky Way. Not only that, many massive cities in Asia and Africa, even underdeveloped, have more light pollution than most American cities. Yes, it is true, per capita we have much more, but it proves light pollution doesn't affirm Western prosperity.

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June 29, 2009 at 6:22 am

Light pollution has nothing to do with political correctness. It is a fact of life that we live with in today's wasteful society. There is none here apologizing for the prosperity of this country (I think our president has done enough of that), we are just addressing a growing problem. I am all for prosperity and safety, but if our country is to be considered as wealthy as you stated, then there is no reason that we cannot come up with a more efficient and less wasteful way of lighting our homes and land. You also mentioned that we are making the world a poorer place. Well, the fact that light pollution exists in such extreme measures here points to the evidence that people like you, in fact, are making the world a poorer place.
One more thing, you "thanked God" for light pollution in your post; Well just to remind you, God did not create light pollution- man did. God created the Milky Way and everything else up there for people like us to enjoy looking at, and it's because of light pollution that it is becoming an enjoyment of the past- something our children may never get to experience.
South Louisiana

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Opa Dean

June 29, 2009 at 11:31 am

Amen Jerry. Political correctness absolutely has no bearing in this situation. The saddest thing to be considered IS that many people will never in their lifetime experience the awesome night sky as our ancestors enjoyed it. Dean, from just North of Baltimore/D.C. area (no dark sky here!!)

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June 29, 2009 at 11:52 am

I grew up in western New Jersey about 45 miles west of New York City. When I was young in the 1950's, I could lay out on the back yard and see the Milky way - even in that conjested area.

Today I live in the Orlando area, and I can't see much unless I go down to the beach 30 miles away. It is such a shame that my children and grandchildren won't be able to experience the night sky the way I could as a kid.

I'm all for light at night, but the technology is here that will allow us to be safe without lighing up the universe! Nature darkened the skies at night so we could recharge...I wonder if Colorado Springs lowers the shades at night to have a dark room to sleep in?

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Nathaniel Sailor

June 29, 2009 at 12:47 pm

When I want to look at the stars, it sucks here. Very hard to see some of the constellations here in FT. Wayne. I want to see the nebulas and galaxies but I go out of town (plus just I got my driver's lincse witch will help). If I want to stay in my backyard I got to get a light-pollution filter which I have like no money for.

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Nathaniel Sailor

June 29, 2009 at 12:49 pm

The thing that didn't make sense at times was the comment from Colorado Springs.

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Mike Hermsen

June 29, 2009 at 2:22 pm

People may not like Wal Mart that much, but I have to give the store near us kudos for their exterior lighting that they have. You can drive by it and swear it is closed. I don't know if they have learned from other areas of the country with restrictive light pollution laws, but it is easy on the eyes and my scope. Don't even know they are there by the lack of a "light signature".

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June 30, 2009 at 5:44 am

I'm very interested in the question of light pollution per capita - it would be fun to create an index of light pollution for the US. Has anybody processed the maps to produce tabular data?

Tony responds: Yes, I have done precisely that, and will post the results soon.

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Tony Flanders

June 30, 2009 at 7:50 am

Here are a few more thoughts. First, I obviously don't agree with "Colorado Springs," but I do think that he has some valid points that can't be dismissed lightly. I'll probably post another blog some time posing as a devil's advocate, giving the arguments *against* light-pollution control. Second, although I value the comments of Tom from Germany and Hendrik from Belgium, they illustrate the hazards of generalizing from specific experiences. I know another observer who reports seeing the Milky Way fairly easily from downtown Munich, and the SQM database has numerous readings from Germany in the range of 21.0-21.5 -- levels where the Milky Way is not merely visible but genuinely magnificent. Likewise, I know an observer whose regular "dark site" is in the Netherlands near the border with Germany, much less than 270 km from Oostende.

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Martin Morin

July 3, 2009 at 8:46 am

You should see Montreal's light pollution which is almost as worst as New York but have 5.2 times less population. Why? Because electricity is too cheap in the province of Quebec and everybody puts lights everywhere! Very sad.

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P. Edward Murray

July 3, 2009 at 12:52 pm

The only sign of the "Politcal Correctness" I see is that of the Ultra Conservative viewpoint that Mr. "Colorado Springs" has written here.

And he sounds more like a Rush Limbaugh "Dittohead" than someone who shares the love of the night sky with us.

It's the same kind of attitude that led us into the "Great Recession" that all of us face today.

And we all know how well that is turning out:(

Light Pollution, Mr "Colorado Springs" is real, if you don't believe me, try going to any major city and try to see the Milky Way, then go to a truly dark site, like Cherry Springs Dark Sky Park.

Then come back here and tell us that Light Pollution doesn't exist!

Tony, I thank you and the good folks at Sky & Telescope:)

P. Edward Murray
Discoverer of "The Basketball Player in the moon"

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John Ståhle

July 3, 2009 at 4:56 pm

I suggest you read this, this guy happens to know, what he is talking about (LEOPOLDO RODRÍGUEZ RÜBKE
Electrical Engineering Dept., Pontifical Catholic University of Valparaíso, Chile.):

Controlling Light Pollution and Saving Energy (in Chile)


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John Ståhle

July 3, 2009 at 5:03 pm

You got it wrong there, mate.

What you, I and everybody else really want is to have sufficient illumination of street and road surfaces.

You don't need to light up the tree tops for the birds to read their evening paper.

Plenty of light, yes, but where it's needed.

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Len, Brooklyn NY

July 5, 2009 at 2:15 am

Don't waste effort answering Colorado Springs, if he could comprehend what's being said he would never have posted that in the first place.
I live in the same house for 47 years. As a child I could see the milky way on a clear night even here in NYC. Now I am lucky to be able to see (naked eye) more than 7 stars on the best of nights.
For a good view of our galaxy I need to drive 6 hours west to get out of the glow of the BoWash corridor. I must drive 90 minutes to reach somewhere that even a hint of the Milky Way is visible.
Many so called "naked eye" objects remain undetectable even through binoculars in the Big Apple.
Esthetically a sad state of affairs. Furthermore, it is being increasingly recognized that lack of natural nightime conditions is having a detrimental effect on the little bit of wild flora and fauna still surviving.
I see my childrens lives already diminished by our ceaseless obliteration of nature without the exercise apropriate discrimination.
The only impediment to using technology to improve our lives in a less disruptive and destructive way, is peoples nature to ignore what benefits all and concentrate on immediate personal gain.

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Grant Hearn

July 6, 2009 at 6:55 am

Living in South Africa's 2nd largest city, I can assure you that the northern hemisphere doesn't have a monopoly on light pollution. Even here in the 3rd world things are a lot rosier than we'd like them to be... However - it's always just a short drive to areas where the light pollution is virtually absent. I am fairly certain that with the exception of the communities of the very poor that have spent their entire lives in the urban bright lights, most South Africans have seen the Milky Way in all its splendour.

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Philip Hall

November 26, 2009 at 5:54 am

I am a British national resident in Tokyo. As your map predicts, the night sky is a lost cause in the city. However, a two-hour drive to the Mt. Fuji region offers some surprisingly good skies where I regularly observe with my 15-inch Obsession scope and am 2/3 of the way through completing the Herschel 400 objects without too much problem. The Milky Way is very visible and has structure though not colour, all constellations' fainter naked eye stars can be readily identified and telescopic views of many deep sky objects are very moving.

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August 16, 2020 at 2:04 am

You can't see the color of the Milky Way without long exposures; our eyes aren't sensitive enough to the light 🙁

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