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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 .
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 300 comets. From 1977 until 1994 he authored the monthly '"Comet Digest" in Sky and Telescope magazine.
Corona Borealis is a small constellation in the Northern Celestial Hemisphere. It is one of the 48 constellations listed by the 2nd-century astronomer Ptolemy, and remains one of the 88 modern constellations. Its brightest stars form a semicircular arc. Its Latin name, inspired by its shape, means "northern crown".
Beta Phoenicis (β Phoenicis, β Phe) is a binary star in the constellation Phoenix. Its apparent magnitude is 3.30, [2] meaning that it can be seen with the naked eye (see Bortle scale). The distance to Beta Phoenicis is poorly known.
The most prominent meteor showers, occurring on approximately the same dates every year, are the Perseids, named for the constellation Perseus and peaking on the night of August 12-13; the ...
The Atlas Coelestis is a star atlas published posthumously in 1729, based on observations made by the First Astronomer Royal, John Flamsteed. [1]The Atlas – the largest that ever had been published and the first comprehensive telescopic star catalogue and companion celestial atlas [2] [3] – contains 26 maps of the major constellations visible from Greenwich, with drawings made in the ...
The Triangulum Galaxy is a spiral galaxy 2.73 million light-years (ly) from Earth in the constellation Triangulum.It is catalogued as Messier 33 or NGC 598.With the D 25 isophotal diameter of 18.74 kiloparsecs (61,100 light-years), the Triangulum Galaxy is the third-largest member of the Local Group of galaxies, behind the Andromeda Galaxy and the Milky Way.
Epsilon Coronae Borealis, Latinized from ε Coronae Borealis, is a multiple star system in the constellation Corona Borealis located around 230 light-years from the Solar System. It shines with a combined apparent magnitude of 4.13, [9] meaning it is visible to the unaided eye in all night skies except those brightly lit in inner city locations ...