The Night Sky is a rotating star finder - or planisphere - that allows the user to recognize the constellations for any time of night, any day of the year. The sky appears to rotate (due to the rotation and orbital motion of the earth), so to be successful recognizing the constellations a beginner needs to know which stars are above the horizon at any time.
Most planispheres attempt to represent the whole dome of the sky on one flat map, creating severe distortion near the outer edges of the map (the southern part of the sky). The Night Sky was specially designed to overcome this problem: two maps divide the sky into north-facing and south-facing views, which are shown on the front and back sides of the chart. When you turn around, simply turn the chart over. This design feature eliminates over 90% of the distortion found in conventional one-sided planispheres.
Other features of The Night Sky were designed with observers in mind:
--Dark stars on a white background make the map easier to read at night with a dim (or preferably red filtered) flashlight. (Under red light the dark blue of the chart becomes a velvety black.)
--The maps are computer-plotted for accuracy and show stars down to a consistent brightness cut-off. What you see on the chart is what is really there.
--The constellation figures emphasize simple patterns connecting the brightest stars, making the constellations easy to recognize and remember.
--The pocket version has fewer stars and omits some of the less conspicuous constellations to minimize clutter and maintain readability.
--The Night Sky comes in a protective vinyl pouch and the chart has plastic outer surfaces for dew resistance.