These Chandler planispheres are designed to reduce distortion by dividing the night sky into two maps, one on each side of the planisphere. This unique system makes it easier to recognize night sky patterns. The bright white background of the planisphere contrasts sharply with the text, making for easy nighttime reading. These planispheres are plastic, making them fully resistant to nighttime dew. Two sizes (5" and 8" diameter) available for each latitude. For most US locations, use 30-40°; northern US/Canada, 40-50°; southern US/Mexico, 20-30°.