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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 zodiacal light is still visible, but does not extend halfway to the zenith at dusk or dawn; light pollution domes visible in several directions; clouds are illuminated in the directions of the light sources, dark overhead; surroundings are clearly visible, even at a distance; the Milky Way well above the horizon is still impressive, but ...
Natural light sources in a night sky include moonlight, starlight, and airglow, depending on location and timing. The fact that the sky is not completely dark at night can be easily observed. Were the sky (in the absence of moon and city lights) absolutely dark, one would not be able to see the silhouette of an object against the sky.
The Perseid meteor shower is typically one of the most dramatic because it produces bright meteors at a high hourly rate. At the shower's peak, skywatchers could see as many as 100 per hour from ...
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 ...