City of lights berlin 2015

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berlin at night, as viewed from the international Space Station. earth Science and Remote Sensing Unit, NASA johnson Space center
man-made lighting weist night ist one des the clearest signs des human activity from space. Most big cities space now deshalb bright the they properly blot out the nighttime sky. Und scientists schutz found this "light pollution" can have lots of unexpected side results — native disrupting our sleep kommen sie messing v wildlife.

Du schaust: City of lights berlin 2015

US urban are much brighter at night than their German counterparts

But as it turns out, there"s a ton von variation bei how various cities light trost at night. A recent paper in the tagebuch Remote Sensing makes use of new space imagery kommen sie study nighttime lighting bei a variety of cities across die United States und Europe.

They found a couple of surprises: us cities, weil das instance, room many mal brighter 보다 German cities of similar size. And, intriguingly, East berlin appears kommen sie emit much more light von capita 보다 its wealthier counterpart in the West. Technology, culture, bright codes, und even die way cities array their highways all seem to schutz a huge impact.

For ns paper, the researchers gathered und analyzed images from NASA"s Suomi NPP satellite und photographs taken by the international Space Station. (You tun können check the end a good library of the latter images here.) A couple of findings:

1) europe cities differ a lot an how they irradiate up

Upwelling radiance of six european cities in the VIIRS two-month composite dataset, v a logarithmic shade scale. The data are reprojected top top a 15-arcsecond grid, which slightly distorts every city’s shape. Dünn courtesy of the earth Observation Group, NOAA national Geophysical charme Center.

On die whole, funding cities bei Western Europe space brighter at night than cities an Central Europe, with ns exception des Warsaw (which is unusually bright) and Amsterdam (which zu sein unusually dim). That"s true also though capitals in Central Europe space often more populous.

Some des this no doubt has kommen sie do through economic advancement — the richer a city is, ns more lighting the usually has — but the researchers hint that there might be "possible difference in lighting culture," too, particularly an downtown areas. One an excellent place to see that is in Germany...

2) East berlin is much more brightly lit than west Berlin

Cropped portion des another bild of berlin taken from ns ISS (iss035e17210). Berlin’s Tegel airport ist labeled v "TXL". Image courtesy des the earth Science und Remote Sensing Unit, NASA johnson Space Center.

The researchers deshalb found a highlight difference in lighting patterns bolzen East and West berlin — a legacy von the old Cold zu sein split. The nighttime lights an East berlin give off an orange hue, greatly from larger low-pressure and high-pressure salt lamps. West Berlin, über contrast, emits much more white light, likely since there are more modern-day LEDs und fluorescents.

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What"s striking ist that East berlin emits much more intense light von capita hinweisen night, even though ns area is poorer. Indeed, that"s true transparent Germany — east German urban that used to be behind die Iron Curtain space brighter than west German cities of similar size.

It"s not entirely clean what accounts zum the difference. Bei Berlin, hinweisen least, one possible factor here ist that the city ausblüten uses some 40,000 gas lamps for lighting, which are difficult zu detect native space. (Many of those lamps are in the West.) one more factor, the researchers note, ist that Berlin"s lighting policy advises making use of outdoor lighting only "when sensible and necessary." That come after a study betwee 2006 und 2008, which found that levels of lighting didn"t actually make the streets any safer.

As a valuable side note, the researchers deshalb were able zu determine whereby all this night light was coming from. An Berlin, at least, about 32 percent come from street lamps, 16 percent from commercial areas, 6 percent from buildings lit up in the city center, and 4 percent native airfields. The rest comes from housing, advertising areas, und "public leistungen areas."

3) united state cities are much brighter than comparable German cities

The VIIRS Day-Night eis (DNB) sum des lights (SOL) zum 28,804 American und 4492 German communities plotted versus population. Trend lines zum the 2 datasets are plotted. If upward lumens/capita to be a constant, ns trend lines would oase equal slopes of one, und the intercept would certainly specify the proportionality constant. Ns large spread of the säule shows the while population is important, it is not ns only variable that determines SOL.

This belastung finding ist striking. Germany and the us are hinweisen comparable levels von economic development. Deswegen you"d think the similar-sized cities bei each nation would look roughly similar punkt night. Yet that"s not actually true. Us cities space many zeit brighter 보다 their German counterparts.

The writer caution that the difference is deswegen striking that it could well it is in due zu some sort des systematic prejudice or error bei the data (although they dominion out several feasible errors the might schutz crept in).

If it"s real, however, die difference can be due zu lots von different factors. In Germany, much of the public lighting zu sein decades old. Differences an tree hülle may so account weil das some des the disparity (many American cities und subdivisions are younger than their German counterparts, und may have less plentiful tree cover). Differences in street width, building height, advertising, and architectural lighting could deshalb affect things.

In any case, the authors note, it shows up you kann sein tell a last about a stadt — that is history, its culture — from researching its lighting. And future research might potentially be useful in figuring out the effectiveness of light-pollution legislations or devising ways kommen sie curb energy waste.

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Further reading

You can find much more photographs taken by astronauts plank the international Space Station here.