Can anyone help me on my light pollution science fair project?

Question

I plan to zoom in on 'earth at night' maps located on the Internet and count the number of pixels in a certain 'area' (e.g. midsized city) and see if light pollution naturally occurs in areas where there is population. Unfortunately, few (or no) maps on the Internet are reliable enough for me to look at (because of low res, no state or country boundaries, chance of being Photoshopped to make the image look 'better', etc...) and the process seems too tedious (city boundaries hard to 'distinguish', time in counting pixels, etc...). Can anyone help me, like introduced me to some special software or a good image (ahem...I mean really good, and better than the IDA stuff or the World Atlas of Night Brightness)? And if you can find the latter (an image) please give me a suggestion on how I can make the project less tedious. If you think I should have a new project, please keep it so I don't have to go outside during the nighttime or have to buy too many things. Thank you!

Answer 1

Buying too many things? I'm with you, but what's wrong with going out in nighttime?

The full World Atlas of Night Sky Brightness has 1 km resolution, or about 0.6 miles. What you might have seen is the preview images for that atlas, which is alot less detailed.


You are very correct, the white "lights at night" pictures are never correct in terms of brightness.
The ones that show |any| light as white look like the country's on fire, and the ones that are show only brighter lights look like mere strings of pearls. The pictures are often taken in full moon (which is incorrect) and all light pollution extends beyond the physical lights.

http://www.lightpollution.it/worldatlas/pages/fig2.htm


These are the correct maps. They are the false-color science images that are scaled to cover the huge difference in brightness (as of 1997), and I guarantee you they have not been photoshopped.

You have to click on the file and unzip it, but it's very large, about 200MB.

(navigate to the other pages if you're not from North America)

If you know how to do it, you can overlay the map on Google Earth, which has boundries. But you have to line it up just perfect, checking city centers everywhere to see if they match.

If not, there's still a website that has full detail light pollution maps for small areas: http://cleardarksky.com/csk/

Find a clock for your city and click on the light pollution map.

Now, you can measure distances, (print it out and get a fine ruler)

East to West and North to South are at different scales though, don't bother measuring diagonally unless you are really smart.


Clicking on the map can give you coordinates, or go to a Google Map.


Now you can find towns out in like Nevada or Wyoming or something, completely surrounded by blackness, and figure out just how little population will create what level of light pollution.

Clicking on the town center will send you to Google Maps, and you can find out it's physical size (miles, feet) on Google Maps Satellite, and look up it's population in an atlas.

You can move the map around, (button: find other clocks, click a cross, click clock, click new light pollution map)

Try several towns of the same light pollution level, average them, do that for gray center, blue center, green center, etc. and now you've got a project. There.

This is easier than counting pixels (because you can measure distance) and you can create cool bell curves of distance to brightness for different populations and put them all on one graph.

Having the cities completely surrounded by black ensures that they aren't being "helped out" by other light domes, and choosing towns with barely a bit of color in the center improves accuracy.

So there. Email me if you need more info.

http://www.darksky.org/news/LtPolMaps.mov
1958, 1975. 1997, 2025

Answer 2

I don't know about getting a high-res image, but I think your goal may be a little too simplistic. After all, what else would be causing the light pollution but population (or possibly forest fires, I guess).

Here's what you might want to consider. If you do find a way of counting the pixels (and I can think of several, but none that you would probably be capable of without a programming background and some astronomy image analysis software), you might want to try seeing if there is a correlation between the population density (people per square mile, say) and the intensity in that pixel. Are some cities better at light pollution control than others? How does Tucson, AZ (well known for it's light pollution standards) compare to a similar-sized city?

Answer 3

A simple way to show the levels of light polution in your area is to use long time exposure photography. You will need a 35mm film camera with a shutter that can be locked open (bulb) or set for 1 or 2 seconds. A tripod, lens cap and cable release.

By pointing to the same constellations and snaping a time exposure you will capture light from not just the stars but the light pollution as well. Once you perfect the technique it is just a simple matter of repeating the experimental exposures in the city, suburbs and country. Your photos will document the level of light pollution quite effectively when compared side by side...

Answer 4

I don't know offhand where to find pictures of high quality (other than NASA,) but there is a direct correlation between the amount of electrical energy used by a city and its light output. You can always look up the average power consumption data for particular cities, and then correlate that into a 2-D graph of high and low consumption areas. Then you can compare your values from the graph to a picture of North America or Europe and see how close you were.

The Department of Energy would have this data. It would also be readily avaible from electrical and gas utilities.

Answer 5

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Answer 6

i dont know of any soft ware or sites were u can optain this pic sorry. its a good idea for a project tho i would try and keep that basic idea just go about it diffrently i cant think of how but you seem like a smart lad.. Best of luck