Light pollution and astronomy

 

The light glare that escapes into the night sky from almost all big urban centres in the industrialised world hides an average of 90 % of the stars that would otherwise be visible to the naked eye.

 

Astronomical phenomena like shooting stars and bright comets can now only be observed well away from the cities with their light emissions.

 

Night skies over Mongolia, a rural area in Lower Austria and Vienna

 

Even on a clear night, only about half the population of Europe can see the Milky Way (Rietschel in Leibniz-Gemeinschaft, 2009).

 

 

Astronomical observatory

"Urban exodus" of astronomical observatories

 

With the advent of artificial lighting, astronomers quickly became aware of the problem of light pollution. Observing the night sky became very difficult in urban observatories especially, and more and more were relocated in rural areas.

 

In the meantime, professional astronomers are forced to use facilities built on remote mountain peaks. What is currently the biggest telescope in the world, for example, is located at an altitude of about 2,600 metres in Chile’s Atacama Desert.

 

Chile and other countries with astronomical observatories have introduced legislation to ensure that light emissions in the surrounding areas are kept to an absolute minimum. The colour spectrum also plays a role. "Light with a strong blue component creates a much more pronounced reflection in the sky than light in which yellow dominates," says Javier Diaz Castro of the Instituto de Astrofisica de las Canarias (Posch, Freyhoff & Uhlmann, 2010).

 

 

Mobile observatory

Programmes for the protection of the starry sky

 

The "International Dark Sky Association" and other organisations have special programmes for the protection of the starry sky and the natural landscape of the night. That makes it possible to define light protected areas (so called "Dark Sky Preserves"). In Austria Grossmugl and the Dürrenstein Wilderness Area in Lower Austria currently aim to get this protection status.

 

Such light protected areas also have potential for tourism. Above all, they stand to benefit from developments in astro-tourism. In the Central Alps there are areas where the view of the starry sky on a clear night is breathtaking. The USA and Canada have had protected areas dedicated specifically to the night sky for a number of years already.

 

http://www.wildnisgebiet.at/de/projekte/lichtschutzgebiet.html

PDF (Resolution der Gemeinde Großmugl)

http://www2.astronomicalheritage.org/images/astronomicalheritage...