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.
Astrophotography, also known as astronomical imaging, is the photography or imaging of astronomical objects, celestial events, or areas of the night sky. The first photograph of an astronomical object was taken in 1840, but it was not until the late 19th century that advances in technology allowed for detailed stellar photography. Besides being able to record the details of extended objects such as the Moon, Sun, and planets, modern astrophotography has the ability to image objects outside of the visible spectrum of the human eye such as dim stars, nebulae, and galaxies. This is accomplished through long time exposure as both film and digital cameras can accumulate and sum photons over long periods of time or using specialized optical filters which limit the photons to a certain wavelength.
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.
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.
Observational astronomy is a division of astronomy that is concerned with recording data about the observable universe, in contrast with theoretical astronomy, which is mainly concerned with calculating the measurable implications of physical models. It is the practice and study of observing celestial objects with the use of telescopes and other astronomical instruments.
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.
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.
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."
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 people and wildlife, and cutting down on energy usage. Earth Hour and National Dark-Sky Week are two examples of such efforts.
Visible-light astronomy encompasses a wide variety of astronomical observation via telescopes that are sensitive in the range of visible light. Visible-light astronomy is part of optical astronomy, and differs from astronomies based on invisible types of light in the electromagnetic radiation spectrum, such as radio waves, infrared waves, ultraviolet waves, X-ray waves and gamma-ray waves. Visible light ranges from 380 to 750 nanometers in wavelength.
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.
An LED street light or road light is an integrated light-emitting diode (LED) light fixture that is used for street lighting.
The New England Light Pollution Advisory Group (NELPAG) is a volunteer organization founded in 1993 to educate the public on the benefits of using efficient, glare-free outdoor night lighting. It is an affiliate of the International Dark-Sky Association. It is thought that the NELPAG hosted the first-ever website on light pollution, and it hosted the website of the International Dark Sky Association early on before the IDSA copied it over and developed at more fully, leaving the NELPAG website to continue on its own.
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.
Hong Kong has been named the world's worst city for light pollution. Commercial and residential areas Mong Kok, Tsim Sha Tsui and Causeway Bay are found to be the most severe areas of light pollution. Due to the spotlights and LED billboards, Hong Kong’s sky is many times brighter than other cities.
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.
