Glenn Chaple's observing basics: How to navigate the heavens
October 2005: Like our all-sky chart, a planisphere portrays a full view of the night sky.
"In each issue of Astronomy, you'll find an all-sky map a circular chart that shows the appearance of the sky after sunset this month. The all-sky map found on page 63 of this issue can help beginners locate and identify major stars and constellations. As the directions note, you hold the all-sky map overhead and orient it so a direction label matches the direction you're facing. Do your arms tire easily? You also can hold the map in front of you, as if it were a car's steering wheel. Turn it so the direction label corresponding to whichever horizon you're facing is at the bottom.
But, perhaps you want to go outside before sunrise tomorrow, when the stars and constellations will be totally different from what's portrayed on the all-sky map. What then? You need a planisphere!