This final part of the Cambridge Star Atlas consists of six all-sky maps to show the general distribution of different objects in the sky. Each of the six maps shows the whole sky in a so-called ‘equal-area’ projection; the Mollweide projection, named after the man who invented it. ‘Equal-area’ means that in spite of the inevitable distortion the actual area covered by one square degree remains the same, no matter where on the map it is measured. So the distribution, or density of objects, is not influenced by the map's projection.

Unlike the main star charts, these maps show the galactic coordinates. The Galactic Equator is the central, horizontal line, marked 0°. On the main star charts it is represented as a line of dots and dashes, making an angle of almost 63° with the Celestial Equator. The Galactic Center (galactic longitude 0°, see star chart 18) lies close to the point where the constellations Sagittarius, Ophiuchus and Scorpius meet, and is in the center of the galactic maps in this chapter. At the top and bottom of the maps the North Galactic Pole (NGP) and the South Galactic Pole (SGP) are marked. They can be found on the star charts 5 (in Coma Berenices) and 14 (in Sculptor) respectively.

The constellations

The first map gives the positions of the constellations against this unusual grid. Stars down to magnitude 4.5 are plotted, plus some fainter stars to complete the constellation patterns, as on the monthly sky maps.