Many describe observations made at "very dark" sites, but from the descriptions it's clear that the sky must have been only moderately dark. Unfortunately, most of today's stargazers have never observed under a truly dark sky, so they lack a frame of reference for gauging local conditions.
#Visible galaxies at night skychart how to#
On Internet bulletin boards and newsgroups I see many postings from beginners (and sometimes more experienced observers) wondering how to evaluate the quality of their skies with a keen interest in light pollution and astronomy. Likewise, you need accurate criteria for judging sky conditions when documenting unusual or borderline observations, such as an extremely long comet tail, a faint aurora, or subtle features in galaxies. Are your skies dark enough? A precise answer to this question is useful for comparing observing sites and, more important, for determining whether a site is dark enough to let you push your eyes, telescope, or camera to their theoretical limits. How dark is your sky? The relationship between light pollution and astronomy is a concern amateurs and professional astronomers alike. A fully dark adapted observer should be able to spot it under skies good enough to rate Class 4 or better on the Bortle scale. The galaxy M33 in Triangulum is a key indicator of sky conditions.
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