Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: The first world atlas of the artificial night sky brightness   We present the first World Atlas of the zenith artificial night sky
brightness at sea level. Based on radiance calibrated high resolution DMSP
satellite data and on accurate modelling of light propagation in the
atmosphere, it provides a nearly global picture of how mankind is proceeding to
envelope itself in a luminous fog. Comparing the Atlas with the U.S. Department
of Energy (DOE) population density database we determined the fraction of
population who are living under a sky of given brightness. About two thirds of
the World population and 99% of the population in US (excluding Alaska and
Hawaii) and EU live in areas where the night sky is above the threshold set for
polluted status. Assuming average eye functionality, about one fifth of the
World population, more than two thirds of the US population and more than one
half of the EU population have already lost naked eye visibility of the Milky
Way. Finally, about one tenth of the World population, more than 40% of the US
population and one sixth of the EU population no longer view the heavens with
the eye adapted to night vision because the sky brightness.

22
The categories of this paper are: chao-dyn
37
The categories of this paper are: supr-con
12
The categories of this paper are: nucl-th
26
The categories of this paper are: bayes-an
5
The categories of this paper are: gr-qc
14
The categories of this paper are: math-ph
2
The categories of this paper are: math
1
The categories of this paper are: cs
23
The categories of this paper are: solv-int
20
The categories of this paper are: acc-phys
0
The categories of this paper are: hep-ph
10
The categories of this paper are: q-bio
27
The categories of this paper are: comp-gas
33
The categories of this paper are: plasm-ph
15
The categories of this paper are: nucl-ex
29
The categories of this paper are: funct-an