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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.
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. [55]
The scale used to indicate magnitude originates in the Hellenistic practice of dividing stars visible to the naked eye into six magnitudes. The brightest stars in the night sky were said to be of first magnitude ( m = 1), whereas the faintest were of sixth magnitude ( m = 6), which is the limit of human visual perception (without the aid of a ...
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.
This scale is widely referred to by various names, including very commonly "Bortle scale". A large number of the instances of "Bortle Dark-Sky Scale" in books are references to Bortle's paper title "Introducing the Bortle Dark-Sky Scale", which is usually but not always capitalized.
Joseph M. Briggs. Joseph M. Briggs was born on November 25, 1833 [1] to Nicholas Joseph Briggs and Martha J. Chambers in Columbus, Franklin County, Ohio. Joseph M. Briggs was raised on the family's home farm and attended Ohio Wesleyan University, where he met his wife Louisiana Ransburgh, who was 17 years old at the time, 16 years younger.
The Scioto River flows beside downtown Columbus. According to the United States Census Bureau, the city has a land area of 220.04 square miles (569.9 km 2). [1] Unlike many other major US cities in the Midwest, Columbus continues to expand its reach by way of extensions and annexations, making it one of the fastest growing large cities in the nation, in terms of both geography and population ...