Atlas of Worldwide Light Pollution

mgarraha writes: "Researchers at the University of Padua and NOAA have analyzed DMSP data to produce a new atlas of night sky brightness due to artificial lighting. Previous maps only showed the distribution of light sources. Their paper will appear in the Monthly Notices of the Royal Astronomical Society. Here is an AP article."

Comments

Light Pollution Tools

[fishbonez]

Here are some useful tools for estimating the light pollution in your area.

Website using CGI script to estimate light pollution:
http://www.darksky.org/ida/darksky/

Java Applet to estimate light pollution:
http://www.darksky.org/ida/darksky/darksky.html

To help you use the above tools, you'll need to know your latitude and longitude in degrees. Just type in your zip code at the bottom of this page:
http://tiger.census.gov/cgi-bin/mapbrowse-tbl/

When converting latitude and longitude for use in these tools, use a negative number to denote South and West (W); use a positive number to denote North (N) and East (E). For example, "49.147247 N" = "49.147247" and "73.996206 W" = "-73.996206".

compare light to population

[jonbrewer]

Compare light to population and no one should wonder why the US is the biggest polluter in the world. Put together the light intensity of China, India, and Indonesia, and you've got half the population of the world, yet they still put off less light than the NorthEast corridor of the US. That's 3,000,000,000 people to 60,000,000.

Re:Better lighting

[RobYoung]

Most of the light shown in the picture is probably being reflected off of the ground, so lights that just point down will not help. Unless we put a giant shield over the entire earth, then no light would get out and we could see the night sky.... nevermind. :)

One thing to point out, is that the map is using mercator's projection (a way of making a sphere look like a square on a map) and it makes things near the equator a lot smaller than the land far from the equator. This makes places like india, australia and the malasia area a lot smaller compared to europe, canada, and northern US. Those cities in australia, for instance, are a lot larger than some of the canadian cities shown, yet it looks like they give off a heck of a lot less light. I don't think it is the amazing lighting technology they are using.

I'm a pilot. Upshining light... IS GOOD.

[Anonymous Coward]

I'm a pilot. I fly small planes, not big commercial ones. I don't have all the fancy radar, guidance systems, imaging, computers, etc. do do most of the flying for me like the big commercial jets.

Well, if you thought driving at night on an unlit highway with no headlights is bad, then you know what flying at night is like all the time.

I for one delight in being able to use the artificial upshining night lighting to navigate by. It makes the skies SAFER. And that's more important than some stargazing.

If you want darkness, go drive to the boonies.

DMSP earthlights image

[jmorzins]

Some of these satellite photos are really fun. One of my favorites also uses data from the Defense Meteorological Satellites Program (DMSP). They spent months taking pictures of the night time earth, and assembled a beautiful composite image of all light-emitting sources on the earth's surface.

It's a map of light sources, and shows some really interesting structures. The Nile is much brighter than the rest of Egypt, the central U.S. is a grid of cities, and there's a railroad stretching across Russia to the Pacific Ocean.

A small version of the image was an astronomy picture of the day last November (http://antwrp.gsfc.nasa.gov/apod/ap001127.html), and a larger version of the image is also available (http://antwrp.gsfc.nasa.gov/apod/image/0011/earth lights_dmsp_big.jpg). There's a short writeup at http://earthobservatory.nasa.gov/Study/Lights/.

Re:Why the line in USA?

[Imperator]

Why is there this very straight line right down the middle of the US where the east side is very bright, but the west side is very dark by comparison? I might understand if that was where the Rockies started, but to my knowlege it's not. Does anyone know what this line signifies?

That line is a bit west of the Mississippi River. The American conquest and subsequent resettlement of North America was a movement westward. At one point, a wave of settlers stopped just beyond the river, which is a major navigable thoroughfare even today. Too far west of the Mississippi, travel became much harder. Established settlements were few and far between. Food and other supplies were hard to obtain. The American Indians still had yet to be told that they had forfeited their lands, and did not wish to surrender their nomadic patterns of life. All in all, the West was not hostpitable to Americans until they reached the coast. If you look at a map of US states, you'll see that the Western ones tend to be large and often appear to have been created by bureaucrats. The dark area of the US really is comparatively unpopulated.

Re:Falkland Islands

[whatnotever]

Fishing. Massive fleets use massive amounts of light at night to attract fish. In the Falklands, they don't fish it themselves, but they make hellalotta money off the licenses. It's a rich area (fish-wise).

Re:Intelligent choice and design aren't free.

[SteveM]

You're just one more person with an agenda claiming unrelated benefits for compliance ... After reading this story, almost everyone will forget about it, because it's really not very important.

Perhaps you should stay more in tune with current events. Like the power crisis in California. Using less energy is not an unrelated but a pretty direct benefit.

The folks up in Clagary thought so, as you can read here. They expect significant savings in energy by changing to full cutoff light fixtures.

A similar law recently passed in Connecticut and another is awaiting the governer's signature in New York.

Light pollution also takes its toll on the environment in more subtle ways then wasted energy.

From a story at ABCNews.com:

"Darkness for Health

Scientists have now discovered that only when it's really dark can your body produce the hormone called melatonin. Melatonin fights diseases, including breast and prostate cancer. "It turns off the cancer cells from growing," says Joan Roberts, a photo biologist. But if there's even a little light around your bed at night, your melatonin production switches off. "So there may be this natural way that Mother Nature has given us, that is, dark night to keep certain cancers under control," Roberts says. Even watching TV turns on other immune system hormones that should be active only in daytime. They get depleted, and you're more likely to get a cold. Nature needs darkness, too. The immune systems of animals grow weak if there's artificial light at night."

Not getting cancer seems like a pretty significant benefit.

Light pollution also has adverse effects on migrating birds and plant life (the plants can't track the natural light curve and don't properly prepare for winter).

Interested readers my wish to check out the International Dark-Sky Association for more info on light pollution and its effects.

Steve M