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Growth of Light Pollution in North America from 1950’s to
projected date of 2025.
Following information and images provided by
www.darksky.org
late 1950's
- Simulation of
artificial night sky brightness in late 1950's based on
rescaling of 1997 data
mid 1970's
- Simulation of
artificial night sky brightness in mid 1970's based on rescaling
of 1997 data
1997
-
Based on measurements in this
period provided by the Defense Meteorological Satellite Program
2025
- Prediction of
artificial night sky brightness in 2025, assuming a constant
growth rate of 6% per year
Animated Version
- Simulated
Animation of artificial night sky brightness from the 1950's
through 2025
The maps show
artificial night sky brightness and are based on upward light
measured by the Defense Meteorological Satellite Program after
accounting for propagation and scattering of that light in the
atmosphere.
The night sky in
all areas here which are not black (but have other colors) is
considered polluted. Today, two thirds of the USA's population
have lost naked eye visibility of the Milky Way.
The colors
indicate the artificial night sky brightness as a fraction of
the average natural night sky brightness.
Black
-
Close to the natural sky brightness
Blue
-
Artificial sky brightness is more than 10% above the natural
level.
Green
-
Artificial sky brightness is more than 33% above the natural
level.
Yellow -
Artificial sky brightness is equal to the natural level. (Total
sky brightness is double.)
Orange -
The
Milky Way is no longer visible. (Artificial sky brightness is 3
- 9 times the natural level.)
Red
-
Less than a hundred stars are visible. (Artificial sky
brightness is 9 - 27 times the natural level.)
White
-
The North Star is no longer visible. Only the moon, the
brightest planets, and about 25 of the brightest stars are
visible. (Artificial sky brightness is 27 - 81 times the natural
level.)
Pink
-
The Big Dipper is no longer visible. Only the moon, the
brightest planets, and a handful of the brightest stars are
visible. (Artificial sky brightness is greater than 81 times the
natural level.)
The maps depict
the artificial night sky brightness when looking straight up.
This is calculated for sea level and a clear atmosphere.
Images
provided courtesy of the International Dark-Sky Association.
Copyright 2001 Cinzano, P., Falchi, F., and Elvidge, C.D.
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National
Dark-Sky Week
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April 1-8, 2003
Grassroots effort initiated by a High School sophomore is
endorsed by the American Astronomical Society, the Astronomical
League, and the International Dark-Sky Association
A grassroots effort to highlight the beauty of the night sky and
to draw attention to the ever-increasing levels of light
pollution across the United States caused by poorly designed
lighting, has the endorsement of the American Astronomical
Society (AAS) and the International Dark-Sky Association (IDA).
The AAS and the IDA believe that the opportunity to experience
the natural night sky should be available to every citizen of
our nation. This natural resource, which inspires our attempts
to understand the cosmos, should be protected through the use of
well-designed lighting systems that put light where it is needed
and not waste energy through unnecessary illumination of the
sky. Properly designed lighting systems provide safety and
convenience without polluting one of our greatest natural
assets.
This is the second year that Jennifer Barlow, a high school
student from Virginia, has organized this grassroots campaign.
"The night sky has been forgotten by many," she says, and she
hopes that National Dark Sky Week will encourage people to "look
up" and appreciate its wondrous features. As we reestablish that
connection, we hope to raise awareness about how to reduce light
pollution and protect our heritage of dark skies.
The American Astronomical Society and the International Dark-Sky
Association encourage all Americans to use the evenings of April
1st to April 8th 2003, from 10 pm to 12 am (ET & MT) and 9 pm to
11 pm (CT & PT) to attend public star parties, visit their local
planetarium or public observatory, or simply go outside to a
safe, dark location to enjoy the wonder of the night sky.
Learning the constellations, observing the planets, wondering
about the stars and the Milky Way are one of the most basic of
human experiences and should be enjoyed by all.
National Dark-Sky Week is also endorsed by the Astronomical
League, a non-profit federation of 250 astronomical societies
and nearly 20,000 members, and by Sky and Telescope magazine.
More information on National Dark-Sky Week is available
HERE.
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