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The Bortle scale (also known as the Bottle 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.
* 4673 Bortle
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Interactive demo of the Bortle Scale International Dark-Sky AssociationObservingSites.com (North American sites only)
{{Portal bar, Society, Astronomy, Stars, Science Amateur astronomy Light pollution Scales
The Bortle scale (also known as the Bottle 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
John E. Bortle is an American amateur astronomer. He is best known for creating the Bortle scale to quantify the darkness of the night sky.
Bortle has made a special study of comets. He has recorded thousands of observations relating to more than ...
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. Some classes can have very drastic differences from the one next to it, e.g, Bortle 4 to 5.
In popular culture
The band Days N' Daze referenced the scale in the title and lyrics of their song ''Nine on the Bortle''.See also
* 4673 Bortle
*Amateur astronomy
Amateur astronomy is a hobby where participants enjoy observing or imaging celestial objects in the sky using the unaided eye, binoculars, or telescopes. Even though scientific research may not be their primary goal, some amateur astronomers m ...
* Dark-sky movement
* ''The End of Night'' (book)
*International Dark-Sky Association
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/amateur astronomer. The mission of the IDA is " ...
(IDA)
* Light pollution
* Night sky
*Sky brightness
Sky brightness refers to the visual perception of the sky and how it scatters and diffuses light. The fact that the sky is not completely dark at night is easily visible. If light sources (e.g. the Moon and light pollution) were removed fro ...
*'' Sky & Telescope'' (''S&T'')
References
External links
* by '' Sky & Telescope''Interactive demo of the Bortle Scale
{{Portal bar, Society, Astronomy, Stars, Science Amateur astronomy Light pollution Scales