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NGC 4889 is far enough that its distance can be measured using redshift. With the redshift of 0.0266 as derived from the Sloan Digital Sky Survey , and the Hubble constant as determined in 2013 by the ESA COBRAS/SAMBA/Planck Surveyor translates its distance of 94 Mpc (308 million light years) from Earth.
Earth's sky is never completely black – even in the absence of light pollution there is a natural airglow that limits what can be seen. The astronomer H.D. Curtis reported his naked-eye limit as 6.53, but by looking at stars through a hole in a black screen (i.e. against a totally dark background) was able to see one of magnitude 8.3, and ...
For most people, these are likely to be the best observing conditions within their reach. Under such "typical" dark sky conditions, the naked eye can see stars with an apparent magnitude up to +6 m. Under perfect dark sky conditions where all light pollution is absent, stars as faint as +8 m might be visible. [4]
Amateur astronomers commonly express the darkness of the sky in terms of limiting magnitude, i.e. the apparent magnitude of the faintest star they can see with the naked eye. This can be useful as a way of monitoring the spread of light pollution. Apparent magnitude is technically a measure of illuminance, which can also be measured in ...
More than 99% of Americans live under skies polluted by light. But dark skies at the Grand Canyon and more than 145 other spots offer stargazing awe.
the sky is light gray or orange – one can easily read; stars forming familiar constellation patterns may be weak or invisible; M31 and M44 are barely glimpsed by an experienced observer on good nights; even with a telescope, only bright Messier objects can be detected; limiting magnitude with 12.5" reflector is 13; 9 Inner-city sky 4.0
Light pollution is an ever-increasing source of sky brightness in urbanized areas. In densely populated areas that do not have stringent light pollution control, the entire night sky is regularly 5 to 50 times brighter than it would be if all lights were switched off, and very often the influence of light pollution is far greater than natural ...
Paranal Observatory nights. [3] The concept of noctcaelador tackles the aesthetic perception of the night sky. [4]Depending on local sky cloud cover, pollution, humidity, and light pollution levels, the stars visible to the unaided naked eye appear as hundreds, thousands or tens of thousands of white pinpoints of light in an otherwise near black sky together with some faint nebulae or clouds ...