HOW DARK DOES A DARK SKIES DISCOVERY SITE NEED TO BE?
The one outstanding physical requirement for a DSDS is that it be darker than most locations where people live that are within 10 or 20 miles (15 to 30 kilometers) of it. We do feel that it is important to have a comparatively dark sky to qualify to be a DSDS. Although we do not want to discourage anyone from founding a DSDS (please see the end of this section for reassurance!), the figure we are suggesting for the brightest acceptable limiting magnitude is one of about 4.8. This would suffice to show enough exciting naked-eye views for participants who come from the midst of a very highly populated, heavily light-polluted area. If you are not familiar with the concept of a zenith limiting magnitude or how to estimate it, or in any case wonder whether a site you have in mind is darker than magnitude 4.8, you can find the area of your site at Clear Sky Chart and figure out the approximate zenith limiting magnitude by checking on the light pollution map for a location near your planned s
