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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.
This is an extreme naked-eye target that pushes human eyesight and the Bortle scale to the limit [56] +7.25: planet Mercury: seen from Earth minimum brightness [42] +7.67 [57] planet Neptune: seen from Earth maximum brightness [42] (Neptune comes to perihelion in 2042) +7.78: planet Neptune: seen from Earth mean brightness [42] +8.00: planet ...
The particle horizon, also called the cosmological horizon, the comoving horizon, or the cosmic light horizon, is the maximum distance from which light from particles could have traveled to the observer in the age of the universe. It represents the boundary between the observable and the unobservable regions of the universe, so its distance at ...
The total magnitude is a measure of the brightness of an extended object such as a nebula, cluster, galaxy or comet. It can be obtained by summing up the luminosity over the area of the object.
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A judge in Brazil has ordered Adele’s song Million Years Ago to be removed globally from streaming services due to a plagiarism claim by Brazilian composer, Toninho Geraes. Geraes alleges that ...
The curvature of the horizon is easily seen in this 2008 photograph, taken from a Space Shuttle at an altitude of 226 km (140 mi). The horizon is the apparent curve that separates the surface of a celestial body from its sky when viewed from the perspective of an observer on or near the surface of the relevant body. This curve divides all ...