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  2. Limiting magnitude - Wikipedia

    en.wikipedia.org/wiki/Limiting_magnitude

    The limiting magnitude for naked eye visibility refers to the faintest stars that can be seen with the unaided eye near the zenith on clear moonless nights. The quantity is most often used as an overall indicator of sky brightness, in that light polluted and humid areas generally have brighter limiting magnitudes than remote desert or high altitude areas.

  3. Sky - Wikipedia

    en.wikipedia.org/wiki/Sky

    With the advent of artificial light sources, however, light pollution has been a growing problem for viewing the night sky. Special filters and modifications to light fixtures can help to alleviate this problem, but for the best views, both professional and amateur optical astronomers seek viewing sites located far from major urban areas.

  4. Bortle scale - Wikipedia

    en.wikipedia.org/wiki/Bortle_scale

    the sky is light gray or orange – one can easily read; stars forming familiar constellation patterns may be weak or invisible; M31 and M44 are barely glimpsed by an experienced observer on good nights; even with a telescope, only bright Messier objects can be detected; limiting magnitude with 12.5" reflector is 13; 9 Inner-city sky 4.0

  5. Apparent magnitude - Wikipedia

    en.wikipedia.org/wiki/Apparent_magnitude

    Amateur astronomers commonly express the darkness of the sky in terms of limiting magnitude, i.e. the apparent magnitude of the faintest star they can see with the naked eye. This can be useful as a way of monitoring the spread of light pollution. Apparent magnitude is technically a measure of illuminance, which can also be measured in ...

  6. Sky brightness - Wikipedia

    en.wikipedia.org/wiki/Sky_brightness

    Light pollution is an ever-increasing source of sky brightness in urbanized areas. In densely populated areas that do not have stringent light pollution control, the entire night sky is regularly 5 to 50 times brighter than it would be if all lights were switched off, and very often the influence of light pollution is far greater than natural ...

  7. Light pollution - Wikipedia

    en.wikipedia.org/wiki/Light_pollution

    Light pollution is the presence of any unwanted, inappropriate, or excessive artificial lighting. [1] [2] 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 ...

  8. Visible-light astronomy - Wikipedia

    en.wikipedia.org/wiki/Visible-light_astronomy

    The visibility of celestial objects in the night sky is affected by light pollution, with the presence of the Moon in the night sky historically hindering astronomical observation by increasing the amount of ambient lighting. With the advent of artificial light sources, however, light pollution has been a growing problem for viewing the night ...

  9. Sky quality meter - Wikipedia

    en.wikipedia.org/wiki/Sky_Quality_Meter

    The current versions has only one band of observation, that can produce misinterpretations if the light pollution changes from sodium-vapor lamp to LED. [ 8 ] The SQM-L, or "Sky Quality Meter - L," is a model with an additional integrated lens, offering a narrower measurement range of 20° compared to the 84° range of the standard SQM model.