Press Release

First global atlas of artificial night sky brightness shows how humans are enveloping world in ‘luminous fog

By SpaceRef Editor

August 13, 2001

Filed under Royal Astronomical Society, United Kingdom

About two thirds of the population of the world and 99% of people in the
continental USA and western Europe never see a truly dark starry sky from
where they live because of light pollution. Most of them cannot see the
Milky Way and for many, the sky never gets darker than it would during
natural twilight because so much artificial light brightens the atmosphere.
These are just some of the statistics revealed in the First World Atlas of
Artificial Night Sky Brightness by Dr Pierantonio Cinzano and Fabio Falchi
(both of the University of Padua, Italy) and Dr Chris Elvidge (NOAA National
Geophysical Data Center, Boulder, Colorado), which has recently been
accepted for future publication in the Monthly Notices of the Royal
Astronomical Society.

Although there has been general awareness of the growing problem of light
pollution for a number of years, this is the first time that the artificial
illumination of the night sky around the world has been properly quantified
and related to where people live. The work of Dr Cinzano and his colleagues
goes far beyond simple night-time images of the Earth. They started with
data acquired in 1996-97 by the US Air Force Defense Meteorological
Satellite Program (DMSP) then calculated how artificial light is propagated
through the atmosphere to arrive at a set of maps showing the extent and
severity of light pollution around the world. These show that many areas
that appear dark in night-time satellite images are in reality affected by
light pollution caused by brightly lit neighbouring places.

Dr Cinzano commented, “Large number of people in many countries have had
their vision of the night sky severely degraded. And our atlas refers to the
situation in 1996-97. It is undoubtedly worse today.” The stark conclusions
of his team include:

* More than 99% of the US and European Union (EU) populations and two thirds
of the world’s population suffer some degree of light pollution.

* In areas where 97% of the US population, 96% of the EU population and half
the world’s population live, the sky is always at least as bright as it is
when there is a half Moon at one of the world’s best observatory sites
(where the air is dry and clear). For many the sky is as bright as it is on
days close to a full Moon at a good astronomical site. “Night” never really
comes to such places and the sky is always as bright as nautical twilight
(the period of time when the Sun is between 6 and 12 degrees below the
horizon).

* More than two thirds of the US population, about half the EU population
and one fifth of the world’s population live where they no longer have the
possibility of seeing the Milky Way with the naked eye.

* For 40% of the US population, one sixth of the EU population and one tenth
of the world’s population, it is never dark enough at night for human eyes
to become adapted to night vision.

Cinzano, Falchi and Elvidge draw attention to the fact that the adverse
effects of light pollution have not been fully addressed because of the
absence of comprehensive quantitative data until now. However, the rapid
increase in light pollution is one of the most dramatic changes occurring in
our natural environment. It has consequences not only for astronomy, but for
the whole of the biosphere and could have unintended impacts on the future
of society.

MAPS

Colour maps are available as zipped TIFF files from
http://www.lightpollution.it/dmsp/

Click on “The World Atlas of sea level artificial night sky brightness” in the
menu bar on the left. These maps are copyright but samples may be reproduced,
with required credit, in connection with reporting this work in the media.
Please see the copyright and credit notice on the web site
http://www.lightpollution.it/worldatlas/pages/copyright.html

FURTHER INFORMATION

Further information about other work on light pollution by Dr Cinzano and
his co-workers may be found at
http://www.lightpollution.it/dmsp/

A preprint of the paper referred to in this press notice may be downloaded
as a pdf file from
http://debora.pd.astro.it/cinzano/papers.html

NOTES

The information shown in “The First World Atlas” is calculated everywhere
for sea level. This makes it possible for light pollution in different areas
to be compared without the confusion of altitude effects. For more details
see the full paper.

The authors acknowledge the support of the ISTIL — Istituto di Scienza e
Tecnologia dell’Inquinamento Luminoso (Light Pollution Science and
Technology Institute), Thiene, Italy. www.istil.it

Issued by RAS Press Officer

Dr Jacqueline Mitton

E-mail: jmitton@dial.pipex.com

Phone: +44 (0)1223 564914

Fax: +44 (0)1223 572892

RAS Web site: http://www.ras.org.uk

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CONTACTS FOR THIS RELEASE

Dr Pierantonio Cinzano

Dept. of Astronomy, University of Padua, Italy

cinzano@lightpollution.it

Tel. +39 0445 378714

(unavailable until August 29th)