Istituto di Scienza e Tecnologia dell'Inquinamento Luminoso

Light Pollution Science and Technology Institute

The Night Sky in the Next Century

We are studying the effects of the increase of light pollution which is exponential almost everywhere with average yearly growth rates as large as 5%-10% measured both in US and Europe. Some preliminary projections have been tentatively made based on usual growth rates.

Growth of light pollution in Italy 1971, 1998, 2025.

The figure shows the growth of light pollution in Italy. At left the map of artificial sky brightness in 1971 (Bertiau, Treanor, De Graeve 1973); at centre our map calibrated to 1998; at right a possible scenario of the artificial sky brightness in 2025. We compared Bertiau’s map with a map obtained with satellite data using the same propagation law used by them (Treanor law), we determined the average growth from 1971 to 1998 and then we rescaled our map of 1998 to 2025 assuming the same growth.

This figure is copyright but may be reproduced by the press in articles citing our research with the following credit/copyright statement:

Credit: P. Cinzano, F. Falchi, C. D. Elvidge. Copyright 2001 ISTIL, Thiene. Reproduced from ISTIL Report 2001.

Levels correspond to a fraction of a reference natural sky brightness (251 ucd/m^2):

Yellow indicates an artificial sky brightness equal to the natural (so the total is double). Orange corresponds approximately to areas where the Milky Way is very difficult to see. At sea level, where the majority of the population lives, the Milky Way could be mostly invisible from Italy in 2025. Red corresponds to areas where less than a hundred of stars is visible from the zenith to 30 degrees elevation.