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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 .
The Bortle scale is a nine-level measuring system used to track how much light pollution there is in the sky. A Bortle scale of four or less is required to see the Milky Way whilst one is "pristine", the darkest possible.
Location Area (in ha) Bortle Scale Status Notes Australia: The Jump-Up, Australian Age of Dinosaurs: Queensland: 1,400 1–2 Dark Sky Sanctuary Designated on April 27, 2019 Australia: Warrumbungle National Park: New South Wales: 23,312 1 Dark Sky Park Designated on July 4, 2016 Australia: Arkaroola Wilderness Sanctuary: South Australia: 63,000
In order to describe how much light pollution there is at a particular location, astronomers classify night skies based on the Bortle Scale.
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.
See the Bortle scale.) There is even variation within metropolitan areas. For those who live in the immediate suburbs of New York City, the limiting magnitude might be 4.0. This corresponds to roughly 250 visible stars, or one-tenth of the number that is visible under perfectly dark skies.
President-elect Donald Trump complained on Friday that American flags would still be lowered to half-staff in honor of the late President Jimmy Carter during Trump's Jan. 20 inauguration.
All-sky maps of skyglow brightness are produced with professional-grade imaging cameras with CCD detectors and using stars as calibration sources. [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]