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  2. Skyglow - Wikipedia

    en.wikipedia.org/wiki/Skyglow

    [10] [11] Amateur astronomers have used the Bortle Dark-Sky Scale to approximately quantify skyglow ever since it was published in Sky & Telescope magazine in February 2001. [12] The scale rates the darkness of the night sky inhibited by skyglow with nine classes and provides a detailed description of each position on the scale.

  3. Bortle scale - Wikipedia

    en.wikipedia.org/wiki/Bortle_scale

    The Bortle dark-sky scale (usually referred to as simply 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 .

  4. Night sky - Wikipedia

    en.wikipedia.org/wiki/Night_sky

    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. Natural light sources in a night sky include moonlight , starlight , and airglow , depending on location and timing.

  5. International Dark Sky Week - Wikipedia

    en.wikipedia.org/wiki/International_Dark_Sky_Week

    International Dark Sky Week (formerly the National Dark Sky Week) is held during the week of the new moon in April, [1] [2] 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. [3]

  6. Darkness - Wikipedia

    en.wikipedia.org/wiki/Darkness

    The Creation of Light by Gustave Doré. Darkness is the condition resulting from a lack of illumination, or an absence of visible light.. Human vision is unable to distinguish colors in conditions of very low luminance because the hue-sensitive photoreceptor cells on the retina are inactive when light levels are insufficient, in the range of visual perception referred to as scotopic vision.

  7. School bell - Wikipedia

    en.wikipedia.org/wiki/School_bell

    The ringing of a school bell announces important times to a school's students and staff, such as marking the beginnings and ends of the school day, class periods, and breaks. In some schools it may take the form of a physical bell, usually electrically operated. In other schools it may be a tone, siren, electronic bell sound, a series of chimes ...

  8. Dark-sky movement - Wikipedia

    en.wikipedia.org/wiki/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.

  9. Middle School: The Worst Years of My Life - Wikipedia

    en.wikipedia.org/wiki/Middle_School:_The_Worst...

    Middle School: The Worst Years of My Life is a realistic fiction novel by James Patterson that serves as the beginning of Patterson's Middle School series. [1] Published in the United States by Little, Brown and Company on June 27, 2011, the book follows sixth grader Rafe Khatchadorian as he begins middle school and copes with the awkwardness of adolescence, "crushes, bullying, family issues ...