Dark-sky movement

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, ^[1] health ^[2] and safety ^[3] of people and wildlife, ^[4] and cutting down on energy usage. Earth Hour and National Dark-Sky Week are two examples of such efforts.

Contents

• Dark-sky lighting
• Skyglow
• Scotobiology
• Dark-sky preserves
• International Dark-Sky Association
• List of groups
• See also
• References
• External links

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. ^[5] 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. ^[6]

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. ^[7] Light pollution has also been found to affect human circadian rhythms. ^[8]

The dark-sky movement encourages the use of full-cutoff fixtures that cast little or no light upward in public areas and generally to encourage communities to adopt lighting regulations. A 2011 project is to establish "dark sky oasis" in suburban areas. ^[9]

Dark-sky lighting

Dark-sky lighting is a concept important to the dark-sky movement, as it minimizes light pollution. The concept was started in the 1950s by the city of Flagstaff, Arizona. ^[10] Flagstaff is a city of over 70,000 people, but because of its effectively controlled lighting, the skies are dark enough to see the Milky Way, ^[11] and the light dome over the city viewed from some distance has been measured as less than 10% as bright as that over a similarly-sized city (Cheyenne, Wyoming) that has not sought to protect its night skies. ^{[12] [13]} Lights should be shielded on the top and sides so light doesn't go up to the sky and only used when needed (use motion detectors and only the wattage necessary). ^[14] To minimize the visual brightness of skyglow and reduce glare and most other biological impacts, amber-colored lighting is critical (such as formerly high- and low-pressure sodium, or now amber LED - see Skyglow#Dependence_on_light_source). The International Dark-Sky Association certifies fixtures as dark sky friendly, and these will have the IDA Fixture Seal of Approval.

Skyglow

Skyglow is the illumination of the night sky or parts of it, resembling an orange "smog". It occurs from both natural and human-made sources. ^[15] Artificial skyglow is caused by the over-illumination of the sky from large city centres, shopping centres, or stadiums. It consists of light that is either emitted directly upward or reflected from the ground that is then scattered by dust and gas molecules in the atmosphere, producing a luminous background or light dome. These artificial skyglows cause the sky to be up to 100 times brighter in urban areas than a naturally dark sky that is unaffected by artificial light. Natural skyglow can come from natural light sources, such as the Sun, the Moon, the stars, or auroras.

Some communities are becoming aware of this problem and are putting forth efforts to minimize the hazy, orange skyglow. A community in particular is the city of Merritt, British Columbia. An article published July 8, 2010 states that they are making minor changes to lighting in and around Merritt, such as the installment of down-cast lighting to commercial buildings, as part of their light pollution abatement program. ^[16] The benefits of this technological change include "saving energy through better focused lights, preserving the environment by reducing excess light that may affect flora and fauna, reducing crime and increasing safety by more adequately illuminating areas, and reducing health risks." ^[16]

Scotobiology

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. ^[17] 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. ^[18]

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. ^[17]

Dark-sky preserves

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, in the US, 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 list of designated parks is maintained by the Dark Skies Advisory Group ^[19] of the International Union for Conservation of Nature (IUCN).

The parks are put in place by the Dark Sky Places program with the intention to remind us that the night sky serves just as much importance to our culture and history as our day-time sky. ^[20]

International Dark-Sky Association

The International Dark-Sky Association (IDA) began in 1988. A non-profit, it manages the Fixture Seal of Approval program, which offers a third-party rating system judging the "sky-friendliness" of lighting fixtures. Another prominent outreach effort is the IDA Dark Sky Places program, created after a proposal from the Flagstaff Dark Skies Coalition in 2001 and the recognition of Flagstaff as the First International Dark-Sky Community in October 2001. IDA now recognizes over 200 Dark Sky Places worldwide. In 2009, the IDA opened an office for public policy and government affairs in Washington, D.C. to inform lawmakers and lobbyists about the energy efficiency of outdoor lighting and to promote the adoption of energy-saving measures. ^[21] The IDA advances dark sky awareness and protection through promotion of guidelines developed in collaboration with lighting industry partners (e.g. IESNA).^{[ citation needed ]} The recently published (2020) Five Principles of Responsible Outdoor Lighting, are:

• Useful: Use light only if it is needed
• Targeted: Direct light so it falls only where it is needed
• Low Level: Light should be no brighter than necessary
• Control: Use light only when it is needed
• Warm -colored: Use warmer color lights where possible

List of groups

See also

Related Research Articles

Light pollution is the presence of any unwanted, inappropriate, or excessive artificial lighting. In a descriptive sense, the term light pollution refers to the effects of any poorly implemented lighting sources, during the day or night. Light pollution can be understood not only as a phenomenon resulting from a specific source or kind of pollution, but also as a contributor to the wider, collective impact of various sources of pollution.

Lighting or illumination is the deliberate use of light to achieve practical or aesthetic effects. Lighting includes the use of both artificial light sources like lamps and light fixtures, as well as natural illumination by capturing daylight. Daylighting is sometimes used as the main source of light during daytime in buildings. This can save energy in place of using artificial lighting, which represents a major component of energy consumption in buildings. Proper lighting can enhance task performance, improve the appearance of an area, or have positive psychological effects on occupants.

The Commission for Dark Skies (CfDS) is the United Kingdom's largest anti-light-pollution campaign group forming part of the international dark-sky movement.

Skyglow is the diffuse luminance of the night sky, apart from discrete light sources such as the Moon and visible individual stars. It is a commonly noticed aspect of light pollution. While usually referring to luminance arising from artificial lighting, skyglow may also involve any scattered light seen at night, including natural ones like starlight, zodiacal light, and airglow.

A sodium-vapor lamp is a gas-discharge lamp that uses sodium in an excited state to produce light at a characteristic wavelength near 589 nm.

The night sky is the nighttime appearance of celestial objects like stars, planets, and the Moon, which are visible in a clear sky between sunset and sunrise, when the Sun is below the horizon.

The history of street lighting in the United States is closely linked to the urbanization of America. Artificial illumination has stimulated commercial activity at night, and has been tied to the country's economic development, including major innovations in transportation, particularly the growth in automobile use. In the two and a half centuries before LED lighting emerged as the new "gold standard", cities and towns across America relied on oil, coal gas, carbon arc, incandescent, and high-intensity gas discharge lamps for street lighting.

DarkSky International, formerly the International Dark-Sky Association (IDA), is a United States–based non-profit organization incorporated in 1988 by founders David Crawford, a professional astronomer, and Tim Hunter, a physician and amateur astronomer. The mission of DarkSky is "to preserve and protect the night time environment and our heritage of dark skies through quality outdoor lighting."

Architectural lighting design is a field of work or study that is concerned with the design of lighting systems within the built environment, both interior and exterior. It can include manipulation and design of both daylight and electric light or both, to serve human needs.

In the field of physical security, security lighting is lighting that intended to deter or detect intrusions or other criminal activity occurring on a property or site. It can also be used to increase a feeling of safety. Lighting is integral to crime prevention through environmental design. A 2019 study in New York City found that the provision of street lights, an important type of security lighting, resulted in a "36 percent reduction in nighttime outdoor index crimes."

International Dark Sky Week is held during the week of the new moon in April, when people worldwide may turn off their lights to observe the beauty of the night sky without light pollution. This event was founded in 2003 by high school student Jennifer Barlow of Midlothian, Virginia. It has been endorsed by the International Dark-Sky Association, the American Astronomical Society, the Astronomical League, and Sky & Telescope.

A dark-sky preserve (DSP) is an area, usually surrounding a park or observatory, that restricts or reduces light pollution or maintains and protects naturally dark night skies. Different terms have been used to describe these areas as national organizations and governments have worked independently to create programs. DarkSky International (DarkSky) uses "International Dark Sky Reserve" (IDSR) and "International Dark Sky Park" (IDSP) among others when certifying Dark Sky Places.

Scotobiology is the study of biology as directly and specifically affected by darkness, as opposed to photobiology, which describes the biological effects of light.

The Bortle dark-sky scale is a nine-level numeric scale that measures the night sky's brightness of a particular location. It quantifies the astronomical observability of celestial objects and the interference caused by light pollution. Amateur astronomer John E. Bortle created the scale and published it in the February 2001 edition of Sky & Telescope magazine to help skywatchers evaluate the darkness of an observing site, and secondarily, to compare the darkness of observing sites.

An LED street light or road light is an integrated light-emitting diode (LED) light fixture that is used for street lighting.

Ecological light pollution is the effect of artificial light on individual organisms and on the structure of ecosystems as a whole.

Globe at Night is an international scientific research program that crowdsources measurements of light pollution in the night sky. At set time periods within each year, the project asks people to count the number of stars that they can see from their location and report it to the project's website. The coordinating researchers compile this information to produce a public, freely available map of global light pollution. By September 2011, almost 70,000 measurements had been made. The use of data collected by the public makes the program an example of citizen science. Globe at Night began as a NASA educational program in the US organized by the NOAO, and was expanded internationally during the 2009 International Year of Astronomy; it is an offshoot of the GLOBE Program, which focuses on school-based science education.

The End of Night: Searching for Natural Darkness in an Age of Artificial Light is a 2013 non-fiction book by Paul Bogard on the gradual disappearance, due to light pollution, of true darkness from the night skies of most people on the planet. Bogard examines the effects of this loss on human physical and mental health, society, and ecosystems, and how it might be mitigated.

The spectral G-Index is a variable that was developed to quantify the amount of short wavelength light in a visible light source relative to its visible emission. The smaller the G-index, the more blue, violet, or ultraviolet light a lamp emits relative to its total output. It is used in order to select outdoor lamps that minimize skyglow and ecological light pollution. The G-index was originally proposed by David Galadí Enríquez, an astrophysicist at Calar Alto Observatory.

Light pollution is the presence of unwanted artificial light that brightens the night sky. Improperly shielded lights are the source of many of the issues regarding the light pollution in Hawai'i. Urban centers in the cities are often so bathed in light that over a hundred kilometers from the city's edge, the light pollution resulting from the glow is present. Fabio Falchi is quoted as stating that “light pollution is one of the most pervasive forms of environmental alteration” due to its destructive nature in both un- and protected areas such as national parks. Dark night skies are an important natural, cultural, scientific, educational, and economic resource for Hawai‘i.

References

External links

• International Dark-Sky Association
• MyDarkSky – dark sky survey maps
• Outdoor Lighting Regulations and Ordinances on Google Earth Archived 2007-09-30 at the Wayback Machine
• Interactive map comparing U.S. dark sky laws
• The dark sky movement – yahoo
• Jasper National Park Archived 2012-05-12 at the Wayback Machine
• Dark-sky parks of the world ^{[ permanent dead link ]}
• Flagstaff Dark Skies Coalition
• Globe at Night
• Cities at Night
• Dark Skies Awareness Archived 2011-04-10 at the Wayback Machine
• The Consortium for Dark Sky Studies