Dark Skies

[Corey White]

The dark-sky movement is a campaign to reduce light pollution. The
advantages of reducing light pollution include an increased number of
stars visible at night, reducing the effects of electric lighting on
the environment, improving the well-being, health and safety of both
people and wildlife, and cutting down on energy usage.

The movement started with professional and amateur astronomers alarmed
that nocturnal skyglow from urban areas was blotting out the sight of
stars. For example, the world-famous Palomar Observatory in California
is threatened by sky-glow from the nearby city of Escondido and local
businesses. For similar reasons, astronomers in Arizona helped push
the governor there to veto a bill in 2012 which would have lifted a
ban on illuminated billboards.

The Milky Way's visibility is greatly reduced by background light. The
sky needs to be darker than about 20.2 magnitude per square arcsecond
in order for the Milky Way to be visible. This makes the Milky Way
difficult to see from brightly lit urban or suburban areas. Maps of
the artificial night sky brightness show that more than one-third of
Earth's population cannot see the Milky Way from their homes due to
light pollution.

Nocturnal animals can be harmed by light pollution because they are
biologically evolved to be dependent on an environment with a certain
number of hours of uninterrupted daytime and nighttime. The
over-illumination of the night sky is affecting these organisms
(especially birds). This biological study of darkness is called
scotobiology. Light pollution has also been found to affect human
circadian rhythms.

Scotobiology is the study of the role darkness plays in living
organisms and shows that interrupting darkness by light pollution
creates drastic effects for most organisms; changing their food
gathering and feeding habits, their mating and reproduction behavior,
migration behaviour (birds and insects) and social behavior.
Approximately 30% of vertebrates and 60% of invertebrates are
nocturnal, meaning that they depend on darkness. Their everyday
behaviors are biologically evolved to adapt in uninterrupted darkness.

Human health is also adversely affected by the effects of light
pollution. Light during night time hours has been linked to human
cancers and psychological disorders.

Dark-sky preserves are the main contributors to the dark-sky movement.
They are protected areas found mostly in national parks that have a
zero light pollution policy set in by the government and controlled by
the National Dark Sky Association.

As of February 6, 2012, there were 35 formally recognized dark-sky
preserves in the world with Canada in the lead containing 15
preserves. These preserves are located in Nova Scotia, New Brunswick,
Quebec, Ontario, Saskatchewan, Alberta, and British Columbia. Other
countries that have dark-sky preserves are the Czech Republic,
Hungary, Poland, Slovakia, Spain, United Kingdom, and the United
States. A current list of designated parks is maintained by the Dark
Skies Advisory Group of the International Union for Conservation of
Nature (IUCN).

Source: https://en.wikipedia.org/wiki/Dark-sky_movement