Light pollution is the presence of unwanted, inappropriate, or excessive artificial lighting. In a descriptive sense, the term light pollution refers to the effects of any poorly implemented lighting, 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.
Night is the period of ambient darkness from sunset to sunrise during each 24-hour day, when the Sun is below the horizon. The exact time when night begins and ends depends on the location and varies throughout the year, based on factors such as season and latitude.
Naked eye, also called bare eye or unaided eye, is the practice of engaging in visual perception unaided by a magnifying, light-collecting optical instrument, such as a telescope or microscope, or eye protection.
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.
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.
Day for night is a set of cinematic techniques used to simulate a night scene while filming in daylight. It is often employed when it is too difficult or expensive to actually shoot during nighttime. Because both film stocks and digital image sensors lack the sensitivity of the human eye in low light conditions, night scenes recorded in natural light, with or without moonlight, may be underexposed to the point where little or nothing is visible. This problem can be avoided by using daylight to substitute for darkness. When shooting day for night, the scene is typically underexposed in-camera or darkened during post-production, with a blue tint added. Additional effects are often used to heighten the impression of night.
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 the IDA is "to preserve and protect the night time environment and our heritage of dark skies through quality outdoor lighting."
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. Earth Hour and National Dark-Sky Week are two examples of such efforts.
Red Rock Canyon State Park is a state park in the U.S. state of California which features scenic desert cliffs, buttes and spectacular rock formations. The park consists of approximately 27,000 acres (110 km2) within the Mojave Sector of the Tehachapi District of the California State Park System, and is located along State Highway 14 in Kern County, about 80 miles (129 km) east of Bakersfield and 25 miles (40 km) north of Mojave, where the southernmost tip of the Sierra Nevada converges with the El Paso Mountains.
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 artificial light pollution. The purpose of the dark-sky movement is generally to promote astronomy. However, astronomy is not the only objective of conserving a dark sky. A dark night sky is associated with many facets of history, philosophy, religion, societal development, poetry, song, mathematics, and science. Different terms have been used to describe the areas as national organizations have worked independently to create their programs. The International Dark-Sky Association (IDA) uses International Dark Sky Reserve (IDSR) and International Dark Sky Park (IDSP). A third designation, International Dark Sky Sanctuary, was introduced in 2015.
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 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. John E. Bortle created the scale and published it in the February 2001 edition of Sky & Telescope magazine to help amateur astronomers evaluate the darkness of an observing site, and secondarily, to compare the darkness of observing sites. The scale ranges from Class 1, the darkest skies available on Earth, through to Class 9, inner-city skies. It gives several criteria for each level beyond naked-eye limiting magnitude (NELM). The accuracy and utility of the scale have been questioned in recent research. The table below summarizes Bortle's descriptions of the classes. For some classes, there can be very drastic differences from one class to the next, e.g, Bortle 4 to 5.
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.
Poloniny Dark-Sky Park is the first dark sky park in Slovakia. It became the 20th dark sky park in the world.
Street Light (also known as The Street Light: Study of Light and Street Lamp (Suffering of a Street Lamp)) (Italian: Lampada ad arco) is a painting by Italian Futurist painter Giacomo Balla, dated 1909, depicting an electric street lamp casting a glow that outshines the crescent moon. The painting was inspired by streetlights at the Piazza Termini in Rome.
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. This type of lighting is when some or all of the light goes straight up to space, instead of down to the ground or onto objects, and gets wasted. Dark night skies are an important natural, cultural, scientific, educational, and economic resource for Hawai‘i. There is a heightened risk on the dark sky because of urban lighting that lights up the night sky.
Paul Bogard is an American author and dark sky advocate. A native Minnesotan, Bogard grew up exploring the forest and watching the stars near a lake in the northern part of the state. He has lived and taught in New Mexico, Nevada, Wisconsin, North Carolina, and Virginia. He is currently an associate professor of English at Hamline University.
