2.2 Location of the Federation
Our spiral galaxy is described together with how its insets on chart A depict galactic hemispheres, spiral arms, and the location of the United Federation of Planets within the Carina-Cygnus arm.
Our galaxy is a spiral star system with a population of about a hundred billion stars, and has a convex lens shape about 30,000 parsecs* in diameter and nearly 4,500 parsecs in thickness. A view of the galaxy from the side is shown in insert #1 on star chart A. The galaxy, because of its bilateral symmetry, can be divided through its horizontal plane into two equal halves, or “hemispheres.” To differentiate between the two halves, quasar 3C 68 is used as a reference point for galactic north, and the half nearest to this quasar is known as the Northern Hemisphere. Conversely, the half away from the quasar is called the Southern Hemisphere. Also shown in inset #1 is a pointer to quasar 3C 294, which, along with the galaxy’s center of mass, is used to define the X-axis of the standard grid system. The small sphere roughly 30,000 light years, or 9,200 parsecs, from the center is the United Federation of Planets.
By tilting the galaxy about 45 degrees downward, so the viewpoint is from above (inset #2), the spiral arms which make up its outer regions become visible. Also shown are two of the nearer star clusters, NGC 1875 and M 13. These globular clusters are primarily composed of population II stars, older stars that contain few heavy metals. The spiral arms of our galaxy, in contrast, are composed mainly of younger, population I stars.
In inset #3, the galaxy is tilted further to give a top view, looking down on the galaxy from the direction of galactic north. This view clearly shows its overall structure, a series of spiral arms originating from the galactic center in a manner typical of spiral galaxies.
Inset #4 is an enlargement of the area explored by the UFP, a section of the Carina-Cygnus arm near the Orion spur. Parts of the neighboring Sagittarius and Perseus arms are visible. The small sphere near the center of the illustration denotes the Federation. The circle marks the outer boundaries of known space. The reader should bear in mind that Federation space is not a perfect sphere, but rather more closely resembles a somewhat dented ball. These “dents” represent regions under the control of other interstellar groups; such as the Klingon and Romulan Empires. Many planetary systems within the limits of Federation space are not members of the UFP, and space around these systems is considered neutral, and, in some cases, hostile.