Search results
Results from the WOW.Com Content Network
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.
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.
As astronomical magnitudes are a negative logarithmic scale, smaller values indicate a brighter sky and a difference of 5 mag arcsec-2 corresponds to a difference in luminance of 100 times. Typical values will range between around 16 for bright urban skies to 22 for the darkest skies on Earth. [3]
The nine chapters of Bogard's book map to the nine levels of the Bortle scale, which attempts to quantify the subjective brightness and suitability for astronomy of the sky in different environments. Bogard has said of the scale, invented in 2001, "one of the reasons why identifying different depths of darkness is so important is that we don't ...
One’s biological age, which measures the body’s physiological state, may help predict who is at risk for developing colon polyps, a known risk factor for colorectal cancer.
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.
Discover the best free online games at AOL.com - Play board, card, casino, puzzle and many more online games while chatting with others in real-time.