Istituto di Scienza e Tecnologia dell'Inquinamento Luminoso

Light Pollution Science and Technology Institute

Maps of the total night sky brightness

The maps of the the total night sky brightness show the quality of the night sky in the territory. They usually are computed at zenith, accounting for the elevation and the natural sky brightness. In smaller-size maps we also account for screening by mountain and terrain elevation. 

The elevation has effect on the natural sky brightness, on the artificial sky brightness and on the stellar extinction and is obtained from a digital elevation map (DEM). The natural sky brightness depends on the chosen direction of view and on the altitude and it is obtained with Garstang (1989) models which account for the light coming from the entire sky and scattered along the line of sight of the observer and for the given atmospherical conditions. The mountain screening is obtained evaluating the elevation of each pixel along the line which connect each site with each source and then computing the maximum screening angle from which we determine the fraction of the line of sight shielded. This is very time consuming, in particular if the line of sight is not vertical and requires computation for each of its points.  

Darker areas (white color) looks slightly larger in these maps than in maps of artificial night sky brightness. This is an apparent effect due to the large interval of our colour levels (0.5 mag/arcsec^2) which do not show where the artificial sky brightness is a fraction of the natural one.

Total night sky brightness in Europe accounting for altitude (in V mag/arcsec^2)

The figure shows the total sky brightness at the zenith in V band. Download the full resolution zipped TIFF image.

From Naked eye star visibility and limiting magnitude mapped from DMSP-OLS satellite data, P. Cinzano (1), F. Falchi (1), C.D. Elvidge (2)((1) Dipartimento di Astronomia, Università di Padova, Italy, (2) Office of the director, NOAA National Geophysical Data Center, Boulder, CO), Monthly Notices of the Royal Astronomical Society, 323, 34-46 (2001)  

This map is copyright of  the Royal Astronomical Society.

Reproduction Guidelines for use of this image.

The map was computed for clean atmosphere with aerosol clarity K=1, corresponding to a vertical extinction in V band of 0.33 mag at sea level (0.21 mag at 1000m o.s.l., 0.15  mag at 2000m o.s.l.,  horizontal visibility at sea level 26 km.). The map was rescaled from 1996-1997 to 1998-1999 based on the fitting to observations. Each pixel is 30''x30'' in size in longitude/latitude projection. Country boundaries are approximate. Mountain screening was neglected.

Levels correspond to total sky brightness  of V mag/arcsec²: