The Galaxy


"If an item does not appear in our records, it does not exist."
      - Madame Jocasta Nu

The STAR WARS saga is tale of literally galactic scope, in which gain or loss of entire worlds is counted like the boons and casualties of battle. It is a legend of all-engrossing subversion and war encompassing a civilisation without a frontier, in which therefore there is no asylum and everything of value is at stake.

The purpose of this document is to consider the existence of the Galactic Empire and Galactic Republic in terms of their grandest practicalities. Galaxies are stupendous but well-defined physical objects, and therefore the STAR WARS galaxy is not a merely literary figment that writers and fans can arbitrarily reinterpret.

Therefore this commentary commences with an overview of a spiral galaxy as a realistic physical place. We then consider some of the terminology of the galactic regions and the statistics of the galactic civilisation indicated in the official literature. We draw general conclusions about the development, present constituents and distribution of the Skywalkers' civilisation. Finally, the appendices gather some of the most important quotations and images as evidence of the state of the galaxy.

Galactic Structure

In order to appreciate the scope of the Galactic Empire, and in particular the relationship between settlement and resources, it is helpful to have a qualitative understanding of the structure and composition of spiral galaxies in general. The visible matter comprising a spiral galaxy can be defined in terms of three important components: a bright, ball-like central bulge; a relatively flat and wide disk; and a dim, tenuous, spherical halo which surrounds the bulge and disk.

The stars of the bulge are predominantly an old population formed early in galactic history. The earliest generations of stars are poor in chemical elements heavier than the hydrogen and helium that originated in the Big Bang. Heavy elements are produced by nuclear reactions within stars, and released to space when dying stars either explode or dissipate their outer layers more gradually. The scarcity of solid matter during the formation of the oldest stars may mean that planets are rare in the bulge.

The disk is a region of ongoing star formation, populated by stars of diverse ages. The most massive, young, bluish, luminous stars are concentrated in the spiral arms, which are sites of enhanced gas density and consequently pronounced star formation. The spiral pattern is not a fixed structure, but is a kind of density wave rippling through the disk, mediated by the collective gravitational self-attraction of the stars and interstellar matter. The luminous stars that define the spiral arms visually are short-lived, and so the spiral arms suffer a high occurrence of supernovae. However the spiral arms' newly formed planetary systems are rich in heavy chemical elements and may be an attractive strategic resource for galactic empires.

Gas and young stars are most closely concentrated about the mid-plane of the disk, but older and longer-lived stars tend to be more widely diffused in both the vertical direction and longitudinally around the disk. Stars that are old enough to support planets with complex evolved forms of life are evenly spread in longitudinally, and their orbits about the galactic centre regularly take them into and out of the spiral arms. The stellar density of the disk is greatest near the galactic centre (interpenetrating the bulge) and declines with both radial and vertical distance. The disk has no perfectly defined outer surface, but the stragglers at the outer rim and the upper and lower surfaces merge gradually into the halo population of stars.

The disk and bulge are immersed in an immense spherical halo. The halo stars are comparatively sparse: they may be counted in millions while the stars for the disk and bulge are counted in billions. The halo is concentrated towards the galactic centre and tapers off to the limits of the galaxy's gravitational dominion, tens or hundreds of thousands of parsecs outside the disk. Some halo stars are solitary. Others are members of globular clusters: compact, spheroidal swarms of millions of stars that formed at the same time. Planets appear to be absent or rare in globular clusters; it is thought that frequent interstellar encounters may prevent planetary formation or disrupt the orbits of any planets that do manage to form.

Finally, it must be noted that the whole galactic structure is embedded within a "dark halo" that exceeds the combined mass of all the visible stars and gas. This "dark matter", which apparently does not interact with light, is presently known only by its gravitational effects. The distribution of dark matter is wider and not as centrally concentrated as the ordinary matter. It may be an undifferentiated cloud of exotic subatomic particles, without necessarily forming any kinds of local substructures. [Our discussion must end here, because although dark matter is probably well understood in the fictional Galactic Empire, it remains a mystery to science on Earth.]


Having defined the physical structure of a spiral galaxy, we can introduce some of the astrographic terms used by the inhabitants of the Galactic Empire:

Regions within the galactic bulge. Because planets must form from solid matter around later-generation stars, most of the inhabited Core Worlds probably orbit stars in the part of the disk that penetrates the bulge. The distances between habitable star systems are shorter than in outer regions of the disk, but the skies of civilised worlds are all the more crowded because of the density of (mostly barren) bulge stars.
Deep Core
The most central parts of the Core, with the highest density of bulge and disk stars. This region probably contains the galaxy's central super-massive black hole. According to the literature, the Deep Core is undesirable or difficult to traverse. It contains several hundred habitable planets [DESB].
Inner Rim, Mid Rim
Annular regions of the galactic disk, consecutively further from the Core. Industrial and demographic conditions are intermediate between the high civilisation of the Core and the dissipated condition of the Outer Rim.
Outer Rim Territories
Regions around the circumference of the galactic disk. Compared to the inner regions of the galaxy, the inhabited star systems are widely separated here. Planetary populations and development are generally very low.
Unknown Regions
These are systems beyond the Outer Rim, and therefore are not part of the galactic disk. They are probably lone stars in the halo, and perhaps satellite dwarf galaxies. Mainstream civilisation generally neglects this large but empty region, probably because the vast distances between potentially interesting destinations. Nonetheless the "unknown regions" receive considerable attention in the post-ROTJ era, as the home and the resort of the militaristic Chiss.



In at least the middle to outer regions of a spiral galaxy, a large fraction of stars are accompanied by planets. [This is observed to be true of the solar neighbourhood in our Milky Way]. Therefore planetary systems are likely to be common among the medium and later generation stars throughout the disk of the Galactic Empire, from the Outer Rim to the disk component of the Core.

The abundance of heavy chemical elements may vary radially within the galaxy. Outer regions may have lower rates of star formation, and less enrichment with the products of nucleosynthesis in older-generation stars. If so then stars in regions of lower metallicity might tend (with exceptions) to have fewer or less massive planets than stars in other regions. However any particular region of the disk must include stars of diverse ages and metallicities, including at least some with habitable planets.

The oldest stars in the galaxy orbit in the halo, and they may be too metal-poor to have planets. Some younger, stars with planets may have originated in the disk and been scattered into the halo by stellar encounters. Dwarf galaxies in orbit around the Galactic Republic and containing perhaps a few billions of stars may be more fertile for planets and life.

life & sapience

The abundance of life in the Galactic Empire is harder to assess than the abundance of planets, since the range of preconditions for the origins and survival of life are not understood comprehensively. The chances of a planetary system containing microbial life may be a function of the type of star, but may be independent of galactic location.

The circumstances that promote the evolution of complex multicellular life and intelligence are even less well known. The high incidence of supernovae in some galactic regions may affect the survival of complex life, but the tolerances are difficult to quantify. For all we know, supernovae that cause incomplete mass-extinction events may actually stimulate the evolution of complex life in nearby star systems.

Thus the incidence of indigenous sapient species and technical civilisations may vary somewhat with galactic radius. However the homeworlds of sapient species will be evenly distributed in galactic longitude. It takes billions of years for such a species to emerge, and in that time the star orbits the galactic centre many times and its position at that time is independent of the movement of the spiral arms.


Although some astronomical factors may influence the regional distribution of indigenous life and intelligence, there are very few impediments to colonisation by spacefaring civilisations. A galactic region where the evolution of native sapients is suppressed might yet be attractive to settlers arriving from elsewhere.

The supernova rate of the whole galaxy is about three per century, meaning not more than a thousand supernova explosions happened during the history of the Galactic Republic. Although each supernova may have affected some settled worlds, the time-scale of the threat may be long enough so that colonisation is undeterred. Human attitudes to settlement in places affected by earthquakes suggest that colonisation may proceed in interstellar zones at risk of supernovae. If evacuation is timely, a few tens of thousand years of colonisation are likely to be profitable in the long run.


Native civilisations and colonies may be distributed nearly evenly among the stars of the galactic disk, but the concentration of useful natural resources may have both a radial dependence and a correlation with the spiral structure. The youngest star systems (associated with spiral arms) will tend to have greater abundances of heavy chemical elements, which means more raw material for the industries of a galactic civilisation. Particularly young systems may be desirable if the solid raw materials have not had time to aggregate into planets. (In principle, asteroid mining is more efficient than extracting the same materials from the surface or interior of a grown planet with appreciable gravity.)

Mining and heavy manufacturing industries may be concentrated in and near the spiral arms. The infamous Mining Guild does indeed control many barren worlds in those regions [AOTC:ICS p.6]. The interstellar space lanes associated with primary and secondary industries may also concentrate along the spiral arms.

The galactic distribution of primary energy production may differ from that of raw materials. If the extraction of rotational energy from black holes is a favoured energy source, then the Core, globular clusters and parts of the halo may be worthwhile destinations. Activity in such regions would necessarily affect the connections of major hyperspace trade routes.

night skies

Inhabitants of different planets must experience a great variation of night skies, depending on location within the galaxy. At one extreme, in the very centre of the galaxy (the Deep Core of the Galactic Empire), adjacent star systems are typically 300 times closer together than is the case in our solar neighbourhood. This implies that there may be a hundred thousand times as many stars visible to the naked eye from the surface of an Earth-like world. At the other extreme, the night skies of most Outer Rim worlds must be dimmer and poorer than Earth's. People on worlds that are situated far outside the galactic disk will see few stars at all, but the whole galaxy may be visible as a diffuse, milky structure that spectacularly covers much of the sky.

The interstellar clouds of gas and dust in the disk are more highly concentrated about the mid-plane than are the stars of medium age. For observers on a planet within the galactic disk, this matter obscures the view of more distant regions of the galaxy. In visible light, the line of sight from a civilised planet may extend only up to a few thousand light-years in directions close to the galactic plane. In the skies of such worlds, the overall structure of the galaxy is obscured in visible light. Only the nearest local regions of the galactic disk are visible as a milky band encircling the sky.

Essential Statistics

Dimensions & Population

As a spiral galaxy, the Galactic Empire is approximately physically equivalent to the Milky Way. Within observational uncertainties, the disk of the Milky Way is somewhere in the range of 100,000 - 120,000 ly. The disk of the Galactic Empire is 120,000 ly in diameter. The latter galaxy is said to have about four hundred billion stars, whereas the usually quoted estimates for the Milky Way are in the range of two to four hundred billion stars.

The variation in the estimates for the Milky Way is partly due to ambiguity in the definitions of things like the diffuse edge of the disk or the limit of the dimmest, least massive but most numerous stars. The variation is also partly due to the difficulties of doing astronomy from a single vantage point in space. The clutter of the surrounding objects in the galactic disk obscures more distant regions. Interstellar dust clouds limit optical visibility to about three thousand light years in the galactic plane (about 1/10 of the solar distance to the galactic centre). Infrared and radio waves are more penetrating, however.

number of stars in galaxy
[Tales from Mos Eisley Cantina, p.202; Tales of the Bounty Hunters, p.301]
~4 x 1011
number of star systems in galaxy
[Tales of the Bounty Hunters]
~1 x 1011
number of inhabited systems in galaxy
[SW RPG 2nd ed., p.126]
~5 x 107
number of stars in "Unknown Regions"
["billions" = Galaxy Guide 8, p.24;
"hundreds of thousands" = Force Heretic 2: Refugeep.246]
~3 x 109
~3 x 105
number of inhabited systems in Unknown Regions
[extrapolated from above data]
~4 x 105
number of full member systems in Galactic Republic/Empire
[A New Hope p.116; SWRPG 2nd ed]
number of permanently settled systems within Galactic Republic/Empire, including dependencies and protectorates
[SWRPG 2nd ed, p.126]
~5 x 107
sapient population of galaxy
[SWRPG 2nd ed, p.126]
100 quadrillion
number of sapient species
[Tales of the Bounty Hunters, p.301]
2.0 x 107
diameter of galactic disk
[Shield of Lies p.39]
120,000 ly
=3.8 x 1012 m
=3.8 x 109 km


The range of supralight hyperwave communications extends at least as far as from the Core to the Outer Rim, as demonstrated by Lord Vader's communications from near Hoth to the Emperor on Coruscant [in The Empire Strikes Back]. This communiction is effectively instantaneous. However the presence of intervening matter near one transciever may affect transmission (the Executor had to move out of the asteroid field to send a clear transmission). Defensive shields around a transmitting vessel may also obstruct hyperwave communications [AOTC:ICS].

Signals propagating at the speed of light, carried by laser, radio, neutrinos, gravitons or other such waves and particles, will take roughly 60,000 years to reach the Outer Rim from the Core. Lightspeed signals between adjacent star systems could typically take years, and centuries may elapse before a signal reaches the nearest neighbouring inhabited system. However civilised planets are so numerous and galactic history is so long that every planet in the galaxy must be continually bathed in deliberate and unintentional transmissions of intelligent origin.

Since the foundation of the Galactic Republic happened only about 25,000 years ago, the light-speed signals of civilised worlds at that time are still propagating throughout parts of the galaxy. Emissions from pre-Republic times and could still be received, recorded and studied directly, by observational historians who visit suitable galactic regions. Spectacular battles of the Clone Wars, the Galactic Civil War and other recent historical conflicts could be observed telescopically from neighbouring systems for a long time to come.

Primitive civilisations that remain on their homeworlds would readily detect the signatures of galactic civilisation using even the most rudimentary electronic and radio wave technologies. The artificial characteristics of ancient city-worlds like Coruscant might be plainly detectable throughout the galaxy. At that stage it might be impossible for the galactic authorities to continue preserving the innocence of emerging species, on their sanctuary moons and planets.

event or circumstance age or date subsequent range of lightspeed signals (approx. % of galactic disk)
age of unified galactic government (Galactic Republic) ~ 25,000 yr >17%
time since ground-level Coruscant casino last saw sunlight through skyscrapers
[The Courtship of Princess Leia]
> 90,000 yr (from centre) 100%
(from rim) 58%
duration of human interstellar settlement (allowing time for speciation) > several times 105 yr 100%
duration of recorded galactic history
[From the Files of Corellia Antilles]
~500,000 yr 100%


What physical limits does the galactic environment impose upon interstellar travel? What do the capabilities of interstellar travellers (as demonstrated in the canon and the literature) imply about how the galaxy is inhabited and traversed?

For at least several hundred thousand years before the invention of hyperdrive and the consolidation of the Galactic Republic, interstellar travel was possible via sublight means. Vessels moving at a large fraction of the speed of light could fly between planetary systems fast enough that their crew did not die of old age in transit. Relativistic time dilation effects mean that such voyages take much less time from the perspective of the crew than for observers at rest on the ground. (This is the infamous "twins paradox" of relativity.) A journey from the Core to the Outer Rim might take up to 60,000 years in external time, but may take an arbitrarily short amount of onboard time for a sufficiently fast ship.

Sublight interstellar travel remains technically feasible for starships in the hyperdrive age. Relativistic velocities are attainable using ion-drive propulsion, as demonstrated by starfighters in some of the New Jedi Order novels, and as implied by the acceleration and power statistics of many starships [eg. quantified in AOTC:ICS]. Even a TIE interceptor may accelerate to high relativistic velocity in less than 23 hours, and cross between neighbouring inhabited star systems, [Before the Storm, p.282] although it may not carry enough consumables for the pilot to survive.

The benefits of time dilation make relativistic sublight travel an effective way to cross the galaxy, if the ship's rest mass is less than the mass-energy of the carried reactor fuel. Convoys of sublight vessels could adequately conduct trade in a pre-hyperdrive interstellar civilisation, if the continuity of supply is more important than the delivery time for a particular package. Strategically, sublight acceleration is effective for colonisation too, since the colonists' journey is one-way, and it doesn't matter how many centuries elapse on the mother planet during transit.

Hyperdrive travel is a much superior way to maintain a cohesive civilisation, since it allows interstellar travel that is quick from the perspectives of both the ship's passengers and planet-bound observers. A trip across nearly the whole radius of the galactic disk (approximately 60,000 ly), eg. from Coruscant to Tatooine, may take less than one day from the external viewpoint [proven by Darth Maul in TPM]. This mean speed is orders of magnitude greater than c, and it is impossible for an object in hyperspace to move slower than a beam of light. Neglecting the magic of the "jump", the physics of hyperdrive performance seems straighforward up to this point.

However natural time dilation for a faster-than-light vessel should actually lengthen the shipboard time, eg. approaching a limit of 60,000 years for an indefinitely fast journey along the galactic radius. A more modest trip, between galactic sectors, would probably take minutes or seconds of external time, but millennia elapse aboard the ship. It seems that in order to keep the crew and passengers alive, all hyperdrive-equipped starships must incorporate a compensatory artificial time-dilation device, akin to the time-suspending "stasis fields" mentioned in novels [Han Solo at Star's End; Rebel Dawn p.4].

The biggest problem with hyperdrive travel, at least according to Han Solo [ANH], is the hazzard of crashing into something. Thus the distribution of matter in the galaxy is likely to have a great effect on the layout of commercial hyperlanes. The longest free path between interstellar clouds of gas and dust is a local limit on the length of any straight-line hyperspace jump: eg. typically about 3,000 ly near the mid-plane of the galactic disk. Perhaps the most efficient long-range routes are laid in relatively empty space more than a few hundred light-years above or below the dusty component of the disk. Voyagers might jump a thousand light years out of and into the disk at either end of a much longer passage through the near fringes of the halo.



STAR WARS is not a tale of exploration and pioneers, it is a history of conflict within a singular, borderless civilisation that encompasses everything valuable within its sight and reach. The saga of the Skywalkers is unaffected by issues of expansion or of "progress". The settlement and unification of the galaxy happened a thousand generations in the distant past. Galactic technology is essentially optimised to the established way of life, changing only according to millennial cycles of fashion. Nevertheless the subject of early galactic development deserves some clarification, because it has subtle but practical implications about how a galactic civilisation must work.

One of the most important facts about galactic history is that most of it elapsed before the widespread availability of hyperdrive technology. Recorded history extends back over half a million years [From the Files of Corellia Antilles]. The invention of hyperdrive was closely followed by the establishment of the unitary Galactic Republic, only approximately 25,000 years before Luke Skywalker's adventures. By that time humans were already established on worlds such as Corellia and Coruscant, and evidently many others as well. The infamous Xim the Despot, a human, reigned in part of the Outer Rim long before the Galactic Republic [Han Solo and the Lost Legacy].

Human populations isolated on countless worlds had evolved divergently into related anthropoid species, for instance the horned Zabrak and the blue-skinned Chiss. Other species with completely independent biological origins have apparently evolved faces and other features to mimic, attract and exploit humans. We may infer that human interstellar visitors were an important influence on the primitive homeworlds of the Twi'leks and Falleen, for example. The time required for the evolution of numerous divergent species of near-humans and convergent species of pseudo-humans implies that humans were widespread throughout the galaxy for at least several hundred thousand years.

Even before the attainment of faster-than-light propulsion, interstellar colonisation is an essentially non-linear, self-propagating process. Consolidated colonies master their local resources and are eventually able to deploy their own starfleets and interstellar probes. In any year, the rate of further colonisiation is proportional to the number of mature colonies. Even if a new colony takes centuries to develop enough wealth to spread its own colonists, the long-term growth of the civilisation is exponential. It is rather like the reproduction of bacteria: i.e. only limited by the available territory and (metaphorical) food. Mathematically, even if an average settled world produces only ten new colonies of its own in every thousand years, the civilisation will double in size roughly every 69 years. If there exist worlds that are even more effective at producing colonists then the doubling time will be much shorter.

Clearly, the settlement of the entire galaxy must have been finished in a very short time compared to the age of the Galactic Republic, let alone the recorded span of pre-Republic history. The only regions that can remain unsettled are those that are physically unattractive for settlement. It is also clear that even the tiniest initial head-start in the race for galactic colonisation inevitably gives that species an advantage of overwhelming numerical superiority throughout the rest of galactic history. To undermine the dominance of the humans and near-humans in the affairs of millions of worlds would require an incredibly insidious plague (of a kind that lacks an evolutionary interest in the survival of its host), or some other comparably virulent self-propagating disaster.


Let's now consider the specific means for galactic exploration.

Sublight Exploration

There is plenty of time for the mainstream, human-dominated civilisation to have propagated throughout the entire disk of the galaxy. Sublight travel is sufficient to explore all reaches of the galaxy. Manned scouts are not necessary; probes have the virtue of being cheaper and more expendable.

  1. Coruscant has been urbanised, to the extent of blocking sunshine to the lowest levels, for over 90,000 years [The Courtship of Princess Leia p.43]. The radius of the galactic disk [Shield of Lies] is only 60,000 light years. Therefore the entire galaxy is easily within human reach even if travel was exclusively sublight.

  2. The literature contains references to other starfaring human cultures that are on the order of hundreds of thousands of years old. SWAJ#8 says that the Gree recognised humans as an interstellar (but not necessarily hyperdrive-using) species, and their peak was several hundred thousand years ago. At least several hundred thousand years of isolation are necessary to produce offshoot human species such as the Chiss, Zabrak, Yoda's species etc.

Hyperspace Exploration

Using hyperdrive, a starship can travel from the Core to the Outer Rim in a matter of days (as demonstrated by Darth Maul in The Phantom Menace and the occupants of the Millennium Falcon in A New Hope.) This mode of travel is innately fast enough to put the entire galaxy within easy reach, and there are only a few conceivable practical limitations to travel. Firstly the number of possible destinations is so large that no individual is likely to see more than a tiny fraction of the galaxy's systems in a lifetime. However a modestly organised bureaucracy could easily catalogue every star or other major object, and a basic database could easily fit in a hand-held computer.

The second practical criterion is that travellers should be able to reach their destination without crashing into anything during the trip. Physical obstruction is a major concern, according to Han Solo in A New Hope, and in the elaborations in the rules developed for the roleplaying games. However the games and the literature indicate that any obstacle can be avoided if a sufficiently circuitous route is mapped by a living or artificial surveyor.

How hard is it to establish a route to any particular destination? How much time does it take? It evidently doesn't take much effort at all, providing that someone has an incentive to reach the particular part of space. The Dark Empire Sourcebook documents that the Deep Core was charted within just a few years, using merely "thousands" of probots, at the behest of Senator Palpatine. This exercise is trivial compared to the galaxy's total industrial capacity, which is capable of building a moon-sized battle station in secrecy. In fact this number of probes is many orders of magnitude less costly of materials than a single star destroyer. Furthermore the reported survival rate of the probes is respectable, considering their disposability.

Since the Deep Core is the central, densest part of the galaxy*, the exploration of any other region must be far cheaper and safer. The halo, being the emptiest region, is likely to be easy but unattractive to explore. The disk of the galaxy is both more penetrable and relatively richer in resource systems than the Deep Core. Therefore if there were any unexplored regions in the disk, they could and would be filled within years, with much less than a Palpatine effort. One part of the disk is as good as any other. It is ludicruous to suppose that huge arcs of the disk could remain neglected when they have the same average density of desirable resources and emerging or advanced native civilisations as the rest of the disk. On the timescale of the history of the Galactic Republic, the circumstance of an entire sector remaining unknown can only be explained by a poverty of physical resources and/or physical remoteness from the galactic core and disk.

More conclusively, The Empire Strikes Back provides canonical proof that a survey of extensive regions of the galaxy is practical. If the Unknown Regions were seriously impenetrable and constituted a huge portion of the galaxy, then the Rebel Alliance could have hidden there in complete security. They would need only to survey a route to a single new system. Conversely, Lord Vader was able to order thorough inspection of a vast number of remote systems, with reasonable confidence of success. Open space was big enough to hide a rebel fleet forever [Return of the Jedi], but the Empire was able to send probot scouts to a statistically significant proportion of all the galaxy's habitable planets.

* The central regions of the Milky Way can be assumed to be comparable to the Deep Core of the Galactic Empire. There neighbouring stars are typically 300 times closer than is typical near our Sun.


As elucidated above, the propagation of interstellar colonialism, even via sublight interstellar transport, is rapid compared to the age of the Galactic Republic, let alone the duration of recorded history. The exponential diffusion of settlements means that the all the desirable parts of the galactic disk and bulge must have been evenly settled long ago. In order to be left neglected, a region would have to be particularly remote, sparse of stars, poor in terraformable worlds, or barren of material resources. It simply isn't realistic to suppose that one arbitrarily cut section of the disk might remain "unknown" throughout the age of human space travel.

Indeed even the tiniest rate of local growth would have the potential to cause explosively exponential growth on the galactic scale, and from this we can induce that the Galactic Republic persists in a condition of maximal equilibrium, exploiting the available resources to their sustainable limit. In the Skywalker era there must be an overall balance between the expansion and decline of local patches of civilisation.

In the equilibrium condition of the galaxy, the population is distributed according to the availability of habitable planets, and the accessibility and density of surrounding resources. However industry and population need not be concentrated in the same star systems or even the same parts of a galactic sector. Industry may be concentrated offworld and in barren systems, but population may be concentrated on the relatively rare habitable planets. (Rare relative to the resources used to sustain the populated worlds.) A populous planet may be supported by the industry and agriculture of a much larger number of outposts and dependencies.

On the larger scale of entire sectors, it is simply uneconomical to establish populous colonies far out in the halo, beyond the galactic rim. Intergalactic exploration is even more unattractive and unaffordable, compared to the comforting certainties of the resource-rich regions of the galactic disk. Thus the central concentration of resources and habitats in the disk and Core exert a compelling centripetal attraction that profoundly affects the long run of galactic history.

The central galactic regions enjoy appreciable local concentrations of resource systems, short local travel times and good accessibility to Rim regions in every direction. These circumstances contribute to the concentration of wealth and political power in the Core worlds. The biological homeworld of the humans — the original source of the spacefaring civilisations that eventually gave rise to the early users of hyperdrive on Corellia and Coruscant — is now a forgotten irrelevance.

Modern galactic society generally looks inwards and cares little for the outside universe. Those who look outwards, such as the ExGal Society [Vector Prime] are regarded as eccentrics. The maintenance of routes for travel and trade is a process under the control of great institutions like the Trade Federation and the galactic government, rather than a matter of individual initiative. Colonisation and the establishment of trade routes requires some investment and risk, but the obstacles to exploration are insignificant on the time scale of the age of the Galactic Republic, and even the densest part of the galaxy was surveyed in a surreptitious effort lasting only a few years.


Due to the fundamentally self-propagating nature of interstellar colonisation, and the proven permeability of even the densest galactic regions, any gaps in the exploitation of the resources and hospitable worlds of the galaxy are certain to be filled at an exponential rate, with a doubling time-scale that is very short compared with the age of the Galactic Republic. As its name implies, the Galactic Republic was almost certainly a fully pan-galactic government from its very beginnings.

However the STAR WARS literature features a handfull of planetary systems that are habitable but nonetheless neglected. How may we explain these (numerically insignificant) pockets of isolation and wilderness? How is it possible for there to exist any "wild space"? Several possibilities are apparent:

  1. Some worlds are neglected because they are remote or economically unattractive. Self-interested colonists and traders are likely to prefer the galactic regions that have a high density of habitable worlds and nearby resource systems. Even the most clement planet imaginable may be unable to attract civilisation if its sun orbits tens of thousands of light years outside the galactic disk. In denser galactic regions, a few planetary systems may be practically inaccessible to hyperdrive travel if they are completely immersed in a massive nebula.
  2. Temporary gaps in galactic civilisation may occur due to interstellar natural disasters. In the galaxy, supernovae occur irregularly every few decades. Each one is likely to cause global mass extinction in surrounding systems. It might be necessary to evacuate any thing from a few worlds up to a whole sector. Worlds may be vacant for some time, but terraforming over decades or centuries could restore them.
  3. Some worlds may be left untouched for the sake of environmental conservation. A sapient species' homeworld may be left as a sanctuary if they are technologically unready to join galactic civilisation (eg. the santuary moon of Endor in ROTJ).
  4. Regions may be rendered temporarily inaccessible by a cartographic calamity. Administrative power appears to be intensely centralised in the Galactic Empire/Republic and non-governmental entities like the Trade Federation and Mining Guild. The downfall of one or more of these institutions, and the loss of their exclusive databases, may cause many systems to be lost for the purposes of interstellar travel. This possibility is foreshadowed by the Trade Federation's transport monopolies at the start of the Clone Wars [AOTC:ICS, p.19]. A more explicit threat is issued in Union.

Appendix A: Visual Evidence

There are several explicit references to the scope of the galactic civilisation and its environment throughout the visual media of the official STAR WARS literature. These include realistic depictions of the galaxy from outside, and schematic maps showing the physical locations of systems.

Jedi Archive Map

Obi-Wan Kenobi sought to learn about the planet Kamino in the Jedi Archives, and displayed his non-results in an intriguing flat-screen image of the galaxy. This picture is especially significant and interesting because it is not a pure schematic, but appears to be a nearly photographic representation overlain with spatial reference markings. We can assume that the galaxy really does look like this image, when viewed in at least some particular choice of wavelengths from a certain point of view.

The depicted bulge appears exceptionally bright and prominent, but this may be an effect of image saturation. Dark markings on the near side of the disk appear to obscuring dust lanes. There appear to be two bands of brightness on the north and south sides of the galactic axis, but it isn't clear whether they are an astronomical phenomenon or merely cartographic markings.

The bulge and disk of the galaxy are entirely enclosed within a pill-shaped cyndrical surface. This presumably shows the extent of charted and accessible space (as far as the Jedi are concerned). Realistically, there may be a smattering of a few million halo stars outside this region.

Remarkably, two more spiral galaxies appear in the top left and bottom right corners of the image. They may be more distant galaxies that coincidentally lie in the background, or they may be nearer but smaller satellite galaxies that are gravitationally bound to the Galactic Republic. In projection the intergalactic separations appear comparable to the galactic diameters, which cannot be literally true because tidal forces would distort the galaxies' shapes if they were so close. Therefore the other galaxies must really be located somewhat in front of or behind the main plane of the picture.

* * * * * * * * *
Flat-screen map of the galaxy in the Jedi Archives.

Naboo Yacht Map

A second galactic map (of sorts) was presented when Senator Amidala led Anakin Skywalker into defiance of the Jedi Council, to rescue his master on Geonosis.

The first image on the screen shows a direct view of the face of a galactic disk. The spiral arms do not appear as tightly wound nor the bulge as wide as in the Jedi Archive map. They look like different galaxies, but perhaps this is an artefact of a different kind of cartographic representation? Perhaps Amidala's map gives emphasis to habitable worlds, or systems fitting some other criterion that excludes most of the bulge. Perhaps the image gives empahsis to economically useful systems, thereby highlighting young and barren planetary systems with high metallicities, concentrated in the spiral arms.

The spiral arms are noteworthy too, because there only appear to be two of them. For comparison, the Milky Way has about four spiral arms. Perhaps the Galactic Republic has another two fainter arms or partial arms in the apparent gaps on the left and right sides of the picture. The presently available images seem indistinct enough to allow that possibility.

The graphical view zooms in towards a rectangular area at the end of one spiral arm, and then it zooms further. The final magnification must be high enough that a single parsec fits across the screen (because Amidala observes that Tatooine and Geonosis are less than a parsec apart). This is a considerable change in scale from an initial view of a galaxy that is about forty thousand parsecs across.

* * * * * * * * *
Senator Amidala's schematics locate Geonosis in relation to Tatooine.

TIE Fighter Maps

Missions in the TIE Fighter computer game are preceded by a galactic map display, which appears to be an attempt at a photorealistic rendering. Companion dwarf galaxies are visible in the background.

The galaxy is tilted in this image, although in intratextual (in-universe) terms it might be on either holographic or flatscreen display. The long semi-axis of the projected image, which corresponds to the galactic radius without perspective distortion, has a vector of (-186,-81). The screenshot is rotated by 23.5 degrees to align the long axis with the conventional X direction. The perpendicular semi-axis has vectors of approximately (-16,25) and (39,-49) in the near and far directions. Thus the projected aspect ratio is approximately 210:91, and the galactic tilt is removed by applying a Y scale factor of 2.31.

TIE Fighter Galactic Map
TIE Fighter galactic map, composited with the rough locations of the Parmel, Parmic, Mylok, Pakuuni, Sepan, Eva-T, Omar, Semag and Yllotat systems marked as they are in the game. Every quadrant of the galaxy here has at least one known system in it.

* * * * * * * * * * * * * *
Raw screenshots of the mission and cutscene galactic maps from TIE Fighter Collector's CD-ROM.

Riders in the Void

In Marvel's issue #38, Riders in the Void, Princess Leia and Luke Skywalker departed their galaxy in a hasty hyperjump to evade Imperial pursuit. They were at such a distance that they could not see stars with their unaided eyes. In the intergalactic void they encountered a large organic warship, which believed itself to be the last survivor of a terrible war in another galaxy. (Perhaps this ship is a refugee from the brutal bio-warfare of the Yuuzhan Vong, who would attempt an extragalactic invasion of the New Republic during a time of turmoil decades later.)

After coming to terms with the ship and its integrated pilot, the pair of rebels were returned to their home galaxy. The view from the extragalactic vessel shows that it entered the galaxy from a direction at right angles to the plane of the galactic disk. In other words, it headed inwards from either the south or north galactic pole.

Some important points to note are:

* * *
The young rebels took an unplanned jump into extragalactic space. They were fortunate to encounter a strange sapient ship. Was this lucky moment of reversion to realspace due to the influence of the Force upon Luke's piloting?

The Sith War

In the conflagration of The Sith War, Jedi Master Vodo-Siosk Baas stood upon the remote world of Dantooine, staring into the evening or dawn sky, meditating upon the state of galactic affairs and his personal failure with his apprentice Exar Kun.

The most astrophysically interesting part of this background is the sight of a spiral galaxy dominating the sky near the horizon. The galaxy is red, presumably because it is viewed through atmospheric haze, like a moon or any other celestial object viewed near the horizon. The galaxy is tilted; not quite face-on and not quite side-on to the planet Dantooine. Is this the Galactic Republic itself, or is it a nearby companion galaxy? It is quite huge in the sky, but not wide enough for Dantooine to be embedded within its disk. If the galaxy in the sky is only a neighbour to the Galactic Republic, then Dantooine is still unlikely to sit within its own galaxy's disk, otherwise brighter and nearer galactic regions would drown out the image of the more distant galaxy.

Master Vodo-Siosk Baas contemplates the state of the galaxy.

Behind the Magic

The CD-ROM multimedia package Behind the Magic includes a face-on representation of the galactic disk. The most noteworthy features are the circular divisions denoting the important economic and demographic zones of the galaxy: the Deep Core, Core Worlds, Inner Rim, Mid Rim and Outer Rim, consecutively in increasing radius, plus more local subregions. These regions are uninterrupted in the directions of galactic longitude. The Outer Rim coincides with the outermost parts of the galactic disk visible in this image.

It is hard to derive much more specific information from the map, since the background image of the galaxy is a bit dark and subdued compared to the labels and foreground graphics, and the image carries the warning: "relative distances not to scale."

The map of the galaxy from Behind the Magic.


The galactic map used in Rebellion shows known and occupied systems throughout the disk.

New Jedi Order

The New Jedi Order novels, commencing with Vector Prime, contain a diagram dotted with points and connecting lines representing some of the planets and interstellar trade routes that were emphasised in the second generation literature. The background graphic resembles a tilted spiral galaxy.

* *
Large- and small-sized scans of the Vector Prime map, an oblique projection with some inhabited systems and regions marked.

Inside the Worlds of Episode I

Inside the Worlds of Episode I contains a schematic map of the galactic disk, indicating the positions of planetary systems mentioned in this book and elsewhere in the prequel literature. The disk is inclined to the projected line of sight, but a set of radial and concentric grid lines provide good clues to proportions. Indeed the presence of grid reference lines suggests that the scaling is intended to be realistic as opposed to the emphatic "treasure map" representation of the Vector Prime map.

About a quarter of the disk is covered with labels for the concentric regions (from the Deep Core to the Outer Rim Territories) rather than names of local systems. This is not in contradiction with the "Galactic Republic" of the canon, and thus is a substantial improvement over previously published cartoon map that gave an impression of half the disk being inexplicably vacant or "Unknown".

map of the galaxy
The map of prequel locations in the galaxy.

Appendix B: Quotations

Prologue Text

The most explicit canonical statements about the state of the galaxy appear in the scrolling prologues to the filmed episodes.

Attack of the Clones refers to the "Galactic Senate" twice, and implies that the role of the Jedi Knights is "maintain peace and order in the galaxy." Thus it appears that there is no other source of authority in the galaxy. The appearance of several thousand separatist systems is alarming at a conceptual level. (This initial rupture is not large compared to the millions of civilised systems in the Galactic Republic, although non-numerical factors may amplify the effective scope of the threat.)

In The Empire Strikes Back, the rebels have been pursued "across the galaxy" by the Imperial Starfleet and Lord Vader has sent probes to find them. The practical constraints of a galactic search are significant. The survey must be able to visit every star system that could feasibly host a self-sustaining rebel base. At the very least this entails sending a probe to every habitable but officially unsettled world in the galaxy. The rebels cannot expect to gain permanent refuge on any previously uncharted world. No habitable region of the galaxy could truly be unknown or inaccessible to the Empire. The rebels can do no better than to settle in an unwatched fringe location.

The prologue to Return of the Jedi names the Galactic Empire again, and states that the rebels are "struggling to restore freedom to the galaxy." This reimpresses us with the galactic scope of the war: the text is not merely describing a developing society with a frontier, or galaxy which is only three quarters explored.

* * *
The scrolling prologue for Attack of the Clones.

* * *
Introductory scrolling text from The Empire Strikes Back. For Lord Vader's search to stand any chance of success, the Empire's reach must potentially extend to all habitable planets in the galaxy.

* * *
Return of the Jedi introductory text.

Dark Empire #1


Following the deaths of Darth Vader and the Emperor and the destruction of the second Death Star, the Rebel Alliance proclaimed a New Republic over three-fourths of the Galaxy.


It is now six years since the Battle of Endor, when the Rebel Alliance successfully destroyed the second Death Star, and Darth Vader and the Emperor met their fates.

In the months immediately following that decisive victory, there was a joyous uprising throughout the Galaxy. The Emperor's tyrannical bureacracy collapsed and the Imperial Fleet was forced into retreat among the planetary systems still firmly under its military control.

The Rebel Alliance, guided by Mon Mothma, then announced the establishment of a New Republic. Its provisional seat of government was to be Coruscant, the ruling world of the Imperial System.

It was a time of peace and celebration. Unfortunately, as things developed, the peaxce was short-lived... and the new confederation proved to be a fragile one.

Soon afterward, the Imperials, in cooperation with the Emperor's Ruling Circle, managed to consolidate control over roughly a fourth of the Galaxy. Whole systems became fortresses, bristling with firepower.

Galaxy Guide 8: Scouts


Many millions of systems in the galaxy lie unclaimed by the Empire or the New Republic. Some of these systems are truly unexplored, and any accounts about them are from remote sensors or hearsay.


The "frontier regions" of space are simply those areas beyond the direct rule of the Empire or the New Republic. Many of the systems closest to the borders of Republic or Imperial space have been thoroughly explored and settled — ....

Some scouts have even reported coming across alien civilisations that have spread out, forming trade empires spanning scores of systems, yet totally unaware of the Known Galaxy.


Wild Space

Wild Space was the last region of space officially opened to exploration before Emperor Palpatine's death. Wild Space encompasses thousands of stars and systems. Under the guidance of the Empire, miners, farmers, families and soldiers have ventured to this region, eager to make their fortune or begin new lives. ....

There are few records regarding the inhabitants and systems of Wild Space. A few trade routes between the major settled worlds are known, but they outlying colonies are unknown to all but the Imperial military forces. There are stories from traders and wanderers of lush worlds, and aliens, and rich treasures, but the truth of these rumours remains unconfirmed.

Unknown Regions

The term "Unknown Region" is a general term for any sector of space which is officially unexplored. Covering literally billions of stars, most of these areas are thousands of light years from the Core Worlds, in the most distant areas of the galaxy. Most of these areas of space remain mysterious and unexplored, and are one of the prime subjects of Scout Service scrutiny. There are also several areas within the boundaries of New Republic and Imperial space which remain "unknown" as fas as the general public is concerned. Many of these regions have been explored, but for some reason remain restricted to civilian travel.

The Unknown Regions are the most dangerous because they are farthest from aid and least understood. ....

Much of what is knwon of these areas of space comes from deep space scans conducted by New Republic and Imperial scientists. making use of visible light, x-rays, neutrino and other forms of radiation, scientists can form a composite picture of these areas of space, at least as they stood thousands of years ago, since that information only travels at the speed of light. However, there is limited information that can be gleaned from this type of observation.

From the Files of Corellia Antilles

In STAR WARS Adventure Journal #14:

The sum recorded history of the galaxy is estimated to total about 500,000 years, and that's just the history we can decipher. Perhaps another 500,000 years or more of history lies unknown, undeciphered, or simply unrecorded. Some cultures left only ruins behind, others left artifacts and craft items, and yet others left only legends.

A Guide to the Star Wars Universe, 2nd edition

Wild Space

Wild Space is the galaxy's true frontier. Once considered part of the Unknown Regions, this area of space was opened to exploration and settlement as one of the Emperor's last acts. Grand Admiral Thrawn was charged with taming this wilderness, and he declared it part of the Empire. However, as the Empire has been too busy to enforce its subjugation, much of Wild Space remains free. [HESB, SWRPG2]

Unknown Regions

The Unknown Regions are the parts of the galaxy and beyond that remain unexplored. Certain regions within the borders of known space are also called Unknown due to the fact that they appear on no official astrogation charts. Some of these places are known to the Empire, the Rebellion, and even fringe society groups, but they remain hidden from the galaxy at large. [HE, HESB, SWRPG2]

Dark Empire Sourcebook



A galaxy is an enormous place indeed, with hundreds of billions of stars. How many habitable worlds might there be? How many civilizations might arise on them? Imagine the complexity and staggering difficulty of uniting so many worlds into a single government. Still, with determination, this was achieved and the Old Republic ruled for 25,000 years.

.... Because of the lack of a centralized government and the continuing conflict over the past six years, many systems have grouped together and formed protective federations, notably the Dawferm Selfhood States and Botor Enclave. Some individual worlds, like Lianna in the Tion, have instituted home rule. Many worlds and groups have declared themselves neutral in the continuing conflict. The Corporate Sector Authority, with control of a vast volume of space, is the largest of these netural states and has been selling weapons to any group with ready cash.


The Deep Core

The peripheral sphere of the galactic core has long served as the seat of civilization for the Old Republic and was called the Core Worlds. The Deep Core, at the heart of the galaxy, had resisted most explorations. The Deep Core is filled with a myriad of blazing suns, some within a few light-hours of each other. the closeness of these stars has long proved a nearly insurmountable hurdle.

Only the single-mindedness of a tyrant like Palpatine could pierce the final veil of this untouched region. Even before his ascension to the presidency, he had funded and promoted long range Deep Core explorations. He ordered the launch of thousands of probots programmed to chart safe hyperspace routes into and through the Deep Core. It took years, but three probe droids succeeded. By this time, Palpatine had assumed the throne.

Modified scout ships were launched into the Deep Core. Survey teams catalogued and surveyed hundreds of potentially habitable worlds. However no heroes' welcome faced the returning scouts. Palpatine ordered them put to death, ensuring that the paths into the Deep Core would remain a guarded secret.

.... Aside from those few known paths, it is virtually impossible to navigate a path into the Deep Core; while it is entirely possible that there are many other paths into the region, the odds of finding one through exploration are low. Palpatine ordered many of the navigable regions mined, patrolled and otherwise blockaded to further prevent unauthorized exploration.

Fortress Worlds

In short order, Coruscant, Alsakan, Grizmallt, Wukkar and a host of the most heavily populated worlds surrendered to Admiral Ackbar's fleet. ....

The Empire Strikes Back comic

Reference to the speed and scope of interstellar travel in the STAR WARS galaxy.


References to the structure of the galaxy in the novels are almost always circumstantial and unspecific. The significance of a particular region varies greatly according to the emphasis of each story, author and medium. A region that appears significant because of its military resources in one series of books may be inconsequential in other terms (eg. population, raw materials, or number of stars) and therefore such places may go unmentioned in other references.

However one noteworthy point is the occurrence of detailed strategic maps of the galaxy. The existence of these maps shows that the whole galaxy is a concern to its rulers, and implicitly contradicts the notion of significant independent powers operating outside the Galactic Empire/Republic.

The Last Command, chapter 25, p.362 (hardcover edition):

Floating there in the darkness, a blaze of light twenty metres across, was the galaxy.

Not the standard galaxy hologram any school or shipping business might own. Not even the more precise versions that could be found only in the war rooms of select sector military headquarters. This hologram was scuplted in exquisite and absolutely unique detail, with a single accurately positioned spot of light for each of the galaxy's hundred billion stars. Political regions were delineated by subtle encirclements of colour: the Core systems, the Outer Rim Territories, Wild Space, the Unknown Regions. From his throne the Emperor could manipulate the image, highlighting a chosen sector, locating a single system, or tracking a military campaign.

Before the Storm p.287:

Hugging herself, she [Leia] stood before the galactic holomap that covered nearly one whole wall of Ackbar's office, staring up into it with haunted eyes.

Force Heretic 2: Refugee p.246:

Hundreds of thousands of stars. It was easy to say the words, but much more difficult to comprehend what they actually meant. On a map, the Unknown Regions comprised only 15 percent of the total volume of the galaxy; but when that 15 percent became the search area for something as small as a planet - which on the cosmic scale was much, much smaller then a needle in a haystack — the true immensity of the task became all too apparent.

In this reference, 15% of the galactic volume obviously includes the galactic halo, since 15% of the volume of the disk would contain about 30 billion stars (from the galactic total of two hundred billion). This quote proves that the Unknown Regions cannot be part of the disk or central bulge. It suggests that the stellar contents of the Unknown Regions amount to between 1/200000 and 1/2000000 of the galactic total: much less than the figure given in Galaxy Guide 8.


Many years after the Battle of Endor, the wedding of Luke Skywalker was disrupted by the protests of a group of embittered loyalists from the Imperial Remnant. They threatened to release a computer virus capable of destroying galactic civilisation by ruining the data that permits interstellar travel and communications. Although the surviving population would presumably retain general astronomical knowledge of the galaxy, precise and practical interstellar travel might take years to reestablish. Meanwhile, without ongoing imports of food and raw materials the most populous city-planets like Coruscant would succumb to famine and environmental disaster.

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Special thanks are due to, in alphabetic order:


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