See: http://cires.colorado.edu/artificial-sky . From the site:

" Light pollution in urban centers creates a sky glow that can blot out the stars. The brighter the area in this zoomable map, the harder it is to see stars and constellations in the night sky. In the United States, national parks are often a refuge for darkness; national parks are shown in purple in the map below"

This came up in the context of a piece in today's NY Times: <http://www.nytimes.com/2016/06/11/science/milky-way-light-pollution-dark-skies.html?rref=collection%2Fsectioncollection%2Fscience>. From that article:

"“One third of humanity cannot see the Milky Way,” said Fabio Falchi a researcher from the nonprofit organization the Light Pollution Science and Technology Institute in Italy. “It is the first time in human history that we have lost the direct contact with the night sky.”"

I do not have the background to comment on technical aspects of what was reported, but given all modern arguments surrounding the influences of climate change, this struck me as a relevant discussion.

                             Joel Kovarsky