Sector (Star Trek)
In the fictional Star Trek universe, a Sector is an area of space, usually designated by a series of numbers to indicate its location in the galaxy.
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Overview of Galactic Sectors
The United Federation of Planets (UFP) set up the current sector designation system sometime in the 24th Century. Before that time, the sector designation system was a very unorganized, as more areas of space were explored, another sector was added on, and built around Federation space like bricks and mortar. Sectors were numbered in the order that they were explored. As the UFP gained more territory, this numbering system became inefficient and confusing.
At the same time, many sectors were improperly referred to as "quadrants" which added to the confusion of what defined a sector as opposed to what defined a quadrant. A good example is Quadrant 904 which under the conventional system would indicate it as the 904th "sector" explored by the UFP.
The first sector to be explored was the space around Earth, which was named the Sol Sector and numerically designated as Sector 001. After that the Alpha Centauri Sector was explored, which became Sector 002, and then the Terra Nova Sector which became Sector 003, and so on.
Regardless of its official designation, the Sol Sector is still proudly known as "Sector 001" to many, because it signifies it as part of mankind's first steps into space.
To better understand the current sector designation system used by the UFP, one must be shown how the Milky Way Galaxy was divided up.
Quadrants
First, the Galaxy is divided into four main Quadrants. Looking down at the Galaxy from the top side, each quadrant cuts the galaxy into four equal slices, each a 90º triangle with a rounded outer edge that angle inward to meet at the galactic core. These quadrants are designated as Alpha, Beta, Gamma and Delta.
If the galactic disk were pictured as the face of a clock; moving clockwise and starting with the 6 o'clock position; the Alpha Quadrant would begin at 6 and end at the 9 o'clock position. The Gamma Quadrant starts at 9 and ends at the 12 o'clock position. The Delta Quadrant starts at 12 and ends at the 3 o'clock position, and finally the Beta Quadrant starts at 3 and ends at the 6 o'clock position.
Planet Earth, is the capital of the UFP, and is located in the Sol System. Sol is a star in the middle of the Orion Arm of the galaxy. The UFP put the Sol system right at the border between the Alpha and Beta Quadrants, however, the UFP considers Sol to be in the Alpha Quadrant.
Sub-Quadrants
Each quadrant is divided up into Sub-Quadrants. Like spokes of a wheel, with the galactic core at the hub, sub-quadrants radiate outward and divide the galaxy into 36 narrow slices. The Milky Way is approximately 100,000 light years in diameter. Each sub-quad is 50,000 ly long which is the distance measured from the center of the galactic core to the outer edge of the galaxy. They are 3,200 ly in height, and approximately 8,727 ly wide at their widest point at the galaxy's edge.
Sub-quads are designated by either a single number or a single letter, starting with 0 through 9, and then becoming the letters A through Z. Each quadrant contains 9 of the sub-quads. The Alpha Quadrant contains sub-quads 1 though 9. The Gamma Quadrant contains sub-quads A though I. The Delta Quadrant contains sub-quads J though R, and finally, The Beta Quadrant contains sub-quads S though Z and also sub-quadrant zero.
Sector Zones
Each sub-quad is further divided by Sector Zones. There are 10 sector zones, spaced 5,000 ly apart from each other that go around the galaxy as circles. They are numbered 0 through 9. Starting at the galactic core is sector zone zero, and ending at the edge of the galaxy is sector zone 9. When the circular sector zone cross a sub-quad they create a cube of space roughly 5,000 ly long, and 3,200 ly high. The width of a sector zone varies, and are smallest at the core and get wider as they taper outward to the galactic edge.
Sector Grids
The cubes created by the intersecting of sub-quads and zones are called Sector Grids. All sector grids are 5,000 ly long, and 3,200 ly high. The widest grids are approximately 8,727 ly wide at the galactic edge and their width gets smaller the closer they are to the galactic core. Near the Sol system, the sector grid would be about 4,500 ly wide. There are 10 sector grid cubes in a line within each sub-quadrant.
Sector Grids are designated first by the Sub-quadrant and then the Sector Zone intersection that form it.
- For example, the sector grid that lies in Sub-quadrant E and in Sector Zone 5 would be Sector Grid: E6 and it would lie in the Gamma Quadrant.
- Sector Grid:17 for example, which is in the Alpha Quadrant, is in Sub-Quadrant 1 and Sector Zone 7. In the case of numbers, the correct designation would be called out as "Sector Grid: One Seven" (not seventeen).
Sector Quads
A sector grid is further divided into 100 Sector Quads of equal volume. (not to be confused with the four main quadrants). Sector Quads are numbered 00 through 99. A sector quad is a 1,000 ly long, and 800 ly high. They are about 900 ly wide near the UFP. They get wider at the galactic edge and thinner nearer the core.
Sector Blocks
A sector quad is then further divided into 1000 Sector Blocks. Near the UFP, sector blocks are 100 lys long and about 100 ly wide with a height of exactly 80 ly. Sector blocks are numbered 000 through 999. Sector blocks are laid out in a 9 X 10 X 10 grid cube, so the resulting sectors are close to perfect 20 ly cubes as possible.
Sectors
A sector block is divided down into 100 individual Sectors, the smallest and final division of space the UFP uses. A sector is an almost perfect cube of space that is 20 light years to a side. At this scale of the galaxy's immense size, the slight curvature of the sector is practically invisible. The sectors are numbered 00 through 99.
Typically, a sector contains about 40 star systems. Two thirds of these stars are either in binary, trinary or quadrinary systems. In dense globular clusters however, a sector may contain several thousand stars, and in the void between the spiral arms of the galaxy, a sector could contain no stars at all.
The Sector Identification System
Sectors are identified by four sets of numbers that represent the grid, quad, and block the sector is located in, and finally the number of the sector itself.
- For example: The sector designated Y6-45-055-14; is Sector 14, located in Sector Block 55, in Sector Quad 45, in Sector Grid Y6. Because it is in the "Y" Sub-Quadrant it would be located within the Beta Quadrant.
Since a majority of explored sectors of the galaxy are located close to the UFP's borders, the Sector Grid designation (such as "Y6", using the example) is usually omitted. It is also not uncommon for a sector to be referred only by its last five digits (055-14) or even just the last two digits: "Sector 14" as most local inhabitants would indicate. Given the numbering system, last two digits will always be unique for a distance of about 80 ly.
Source: Star Trek: Star Charts, by Geoffrey Mandell