A planisphere consists of a circular star chart attached at its center to an opaque circular overlay that has a clear elliptical window or hole so that only a portion of the sky map will be visible in the window or hole area at any given

Since the planisphere shows the celestial sphere in a printed flat, there is always considerable distortion. Planispheres, like all charts, are made using a certain projection method. For

Accurate planispheres represent the celestial coordinates: right ascension and declination. The changing positions of planets, asteroids or comets in terms of these coordinates can be

• Bartsch, Jacob. Usus Astronomicus Planisphaerii Stellati, 1624. (Scans by Felice Stoppa.) The first cartographic use of the term planisphere.
• Uncle Al's Sky Wheel – northern hemisphere planisphere.

The word planisphere (Latin planisphaerium) was originally used in the second century by Claudius Ptolemy to describe the

The upper disc contains a "horizon", that defines the visible part of the sky at any given moment, which is naturally half of the total starry sky. That horizon line is most of the time also

• Celestial globe - the representation of the starry sky on an apparent celestial sphere.
• List of astronomical instruments
• Armillary sphere - a framework of brass rings, which represent the