Tuesday, June 28, 2005

Light Pollution Or Civilization?

There'll be more photos of the Mt. Palomar Open House tomorrow. There are 4 more telescopes at the observatory besides the 200 inch behemoth in the first set of photos.

As at every astronomy event there was information about light pollution. Astronomers spend their lives trying to find places with clear skies and near total darkness. Mt. Palomar itself was chosen as an observatory earlier this century because the light pollution from Los Angeles was becoming too bright for good observation at Mt. Wilson.

Even Mt. Palomar is encountering light pollution. San Diego for years used low sodium lights to help keep the skies dark for astronomy at Mt. Palomar. Recently the city has gone away from those lights. As a night owl and a San Diego resident I have to say I hated the low sodium lights. A city illuminated at night with low sodium lights is an ugly city. There's hardly anything more beautiful than a modern city lit up at night.

This map was displayed at the Open House to show the area where light pollution affects astronomy at Mt. Palomar. (Click photo to enlarge.)
The light pollution zone encompasses a huge area of Southern California. It includes San Diego, a city of over 1 million people, and a county of over 2 million, and the southern part of Riverside County, perhaps the fastest growing region in California. There were some reasonable suggestions given about trying to limit the amount of light that spills up into the sky by hooding lights so the illumination is directed to the ground not the sky. (Click here for more information on limiting light pollution.) But ultimately Southern California, home to millions now and millions more in the future, can only do so much to reduce lighting in order to accomodate an observatory. Astronomy at Mt. Palomar is doomed.

There still remain large areas on Earth where the skies at night are dark. But the future of astronomy is in the sky, in Earth orbit, on the moon, or elsewhere. This famous NASA photograph of the Earth shows where the sky is lit up at night and where it is dark. (Click photo to enlarge.)
(Photo credit to C. Mayhew & R. Simmon (NASA/GSFC), NOAA/NGDC, DMSP.)
The photograph is a visible and striking illustration of where technological civilization exists and where it does not. It also reveals the irony of astronomy, perhaps the first science of civilized humanity. Today the best place to put an observatory is far away from civilization. In terms of light pollution, in fact, the ideal place for an observatory appears to be that patch of utter darkness in East Asia, just north of Seoul and just south of Manchuria: North Korea; about as far from civilization as a person can go in the modern world.


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