Science Fiction Timeline Site Babylon Five History Page
Framed Site
Prophecies and Visions Astronomy Planets of the Earth Alliance Speeches and Monologues Links
***** ****** ***** *****

Stellar Geography in the Babylon 5 Galaxy

Text by Larry King

Babylon 5 trademarks belong to J. Michael Straczynski and Warner Brothers

Thanks to Richard Wakefield, Bret Feinblatt, Marc Carlson, Udo Schuermann, Christopher Novosad-Russo, and Bob Donahue for their help!



Note: Nothing in this file should be taken as an attempt to condemn Babylon 5 for its occasional scientific lapses. I'm just trying to hold sf writers to the exacting standards of science. Besides, the fact that B5 even attempts to attain scientific accuracy is an extremely positive (and rare) thing in itself . . . .

***** ***** *****

A Map of our Galaxy

The following map of our galaxy (the "Milky Way") is taken from the 1994 Cambridge Atlas of Astronomy. I have rotated it so that Earth's sun ("Sol") appears at the bottom left, since that is the same perspective used in the Babylon 5 "War Room Map".

Milky Way Galaxy with B5 Stars Pinpointed

[Click here for a
high-resolution version of this map.]

The dot representing our Sun is, of course, too thick – that one dot includes all stars and planets mentioned in the first two seasons of Babylon 5. In seasons three and four (and in the pilot), more distant stars were mentioned. But the farthest of these, Deneb, is still only 1600 light-years from our sun.

The red border on the map shows the widest extent of the Shadow War (as shown in And the Rock Cried Out, No Hiding Place). It seems likely that Straczynski has changed his ideas regarding the astronomical scale of the events in his story. Read on . . . .

***** ***** *****

Where is Earth?

Earth orbits "Sol", a star which we commonly refer to as "the Sun". Our nearest neighboring stars are just over 4 light-years away. Farther out, astronomers have counted 59 stars within 17 LY of our sun.

There are over 100 000 000 000 stars in the Milky Way Galaxy. The Core of the galaxy is an ellipsoid with 5000 LY as its vertical radius and 10000 LY as its horizontal radius. The entire galactic disk has a horizontal radius of 50000 LY; our sun is around 30000 LY from the center.

Thus, leaving Sol and heading through Sagittarius, it is 20000 LY to the edge of the Core and another 10000 to the galactic center; heading through Gemini it is around 20000 to the horizontal edge of the galaxy. But one can leave the galactic disk by heading "vertically" a mere 1500 LY.

Note from the map that our sun isn't actually in the local (Sagittarius) arm. But the spaces between the arms still contain stars. The motion of stars in a galaxy is very odd – the stars rotate about the center of the galaxy at a much different rate than the spiral arms rotate! Think of the stars as cars, and the arms as "traffic jams" on a freeway – the speed at which the "jam" moves doesn't match the speed of any car. See the texts mentioned at the end for more information.

Thus, there is no "edge" or "rim" to the galaxy. (David Gerrold once commented that trying to find the "edge" of the galaxy is like trying to bisect a sneeze.) We will merely see a gradual increase in the distance between stars as we "leave" the galaxy.

Over 90% of stars can be categorized by their spectra into the classes O B A F G K M . These run from hotter to colder; loosely, we may think of O-type stars as green-white, B as blue-white, A as white, F as yellow-white, G as yellow, K as orange, and M as red.

Other classes exist as well (such as D, white dwarf stars). Our sun is considered a G2 V star: a small yellow star.

***** ***** *****

Where are Earth's Colonies?

Earth itself has a couple dozen colonies, many of which have been referred to by their colonial names. But the only worlds given real astronomical names are:

It is interesting to note that the distances seem to have grown as the show progressed. If we discard the pilot, no colonies farther than 36 light-years were mentioned until fourth season!

There have also been several "Orion" colonies mentioned, but there are a whole lot of stars in the constellation Orion, including the nearby Pi-3 Orionis (26.09 LY from Earth), which Richard Wakefield has suggested may be the home of the Orion Colonies.

For a complete list of human-settled planets mentioned in Babylon 5, see the companion document, Planets of the Earth Alliance.

***** ***** *****

Where is Babylon 5?

This question has seen a variety of interesting answers. It seems likely that Straczynski hasn't been keeping careful track of some of the astronomical data in his show.

In the earliest days of Babylon 5, Straczynski was asked about the location of the space station. Between 1993 and 1994, he variously claimed that Babylon 5 was "in a star-system about 35 light-years from Earth"; that Babylon 5 was "in an undiscovered star-system about 25 light-years from Earth"; or that Babylon 5 orbited a star named Tigris.

One early JMS post even included the bizarrely impossible claim that Babylon 5 is in a star system "that hasn't been discovered at this point in time . . . but in about 50 years, it'll show up on the starcharts. It's a fairly small star, dwarfed and hidden by several nearby binaries that overwhelm the spectrum visible from Earth."

The televised show said nothing of this. We saw Babylon 5 in orbit about an orange planet, which itself orbited a yellow star. The star's name was not given, but the planet was called Epsilon 3.

Finally, Stracyznski seemed to settle on a choice for B5's home star:

Internet posting by Straczynski, 8 November 1994:
I'll have to go check my notes, but I believe it's Epsilon Eridani.
-- jms

From the second-season episode And Now For A Word, telecast May 1995:
Babylon 5 is in the Epsilon Eridani sector.
-- The Reporter for I S N

Internet posting by Straczynski, 9 March 1996:
B5 orbits Epsilon Eridani.
-- jms

So, does this settle the issue? Well, there are still problems.

We have seen in several shows – most notably in Interludes and Examinations – that Babylon 5 and Epsilon 3 orbit a star which is yellow-white in appearance. Indeed, the star looks a whole lot like our sun.

Epsilon Eridani is a K2 star, basically orange to orange-red in color. Like our sun, if one looked directly at it, the star would appear white, but it would have an orangish corona. The star we've seen in the show is white with a yellow-white corona.

Bob Donahue points out that Epsilon Eridani is only about one billion years old, and thus probably too young for interesting life to have evolved. So far, this isn't a problem – there's no reason to believe that any of the races we've seen in the Great Machine on Epsilon 3 are native to the planet.

Epsilon Eridani is 10.67 light-years from the earth (according to the 1991 Gliese list; see appendix for sources). This is certainly much closer than the 25 or 35 light-years mentioned earlier. It also contradicts some more recent data: in Face of the Enemy, Lise Hampton Edgars tells Garibaldi that she didn't want a relationship with someone who was "18 light-years away". Of course, she may simply have forgotten B5's true distance in her annoyance with Garibaldi.

So we seem to have a few possible options:

***** ***** *****

Where are the alien homeworlds?

Fragments of information regarding the other alien worlds were given during the first season of Babylon 5:

Some ways we can use this data to speculate on locations of these planets:

Possibility One. Babylon 5 is in the Epsilon Eridani system. JMS was correct when he said that Centauri Prime is "almost twice" as far from Babylon 5 as is Earth. In this case, Babylon 5 is 10.67 LY from Earth, 10 LY from Narn, and around 20 LY LY from Centauri Prime. (We must conclude that the Centauri year is very short and Londo was referring to 75 Centauri light-years.)

One possible problem with this is that Narn, the Earth Alliance, and the Centauri Republic have each founded several colonies. Putting all three this close seems to make things very complicated.

Possibility Two. Babylon 5 is in the Epsilon Eridani system, but JMS's comment that Centauri Prime is "twice as far" from B5 was in error. Centauri Prime is 75 standard light-years from B5. If Centauri Prime is not in Centaurus, there are tons of nice stars at this distance. If it is in Centaurus, it's about 70 LY from Earth, and there are still tons of nice stars to choose from.

Possibility Three. Both statements about Centauri Prime's location should be taken at face value. This means that the Centauri homeworld is "nearly twice as far from B5 as is Earth", and Centauri Prime is 75 LY from Babylon 5. Conclusion: Babylon 5 is around 40 LY from Earth, and Narn is 10 LY from Babylon 5. Once the distances are this great, there are tons of stars to choose from, of every main-sequence type.

Finally, we should note that nothing has been said about the location of Minbar, Vorlon, Z'ha'dum, or the other alien worlds.

***** ***** *****

How far does "known space" extend?
What is the "Rim"?

According to all the evidence above, the Centauri homeworld, the Narn homeworld, and the Babylon 5 station are less than 100 light-years from Earth. Moreover, all Earth colonies mentioned in through season three were within 38 LY of Earth – except for Antares, mentioned in the pilot.

Many viewers (including myself, the author of "Babylon 5 A to Z", and the authors of the "Babylon Project Role-Playing Game") concluded that this reflected the intended scope of the show.... in other words, all the action in Babylon 5 takes place within 100 or 200 LY of here.

If you study the map above, this would mean that the entire show takes place in the "dot" marking Earth's sun on the map!

The first questions arose as characters began to refer to "the Rim". There seemed to be two main possibilities for what this could mean: the "rim of known space", or "the rim of the galaxy".

The rim of the galaxy is quite far. Going towards galactic "north", one can "exit" the galactic disk after a journey of around 1500 light-years, but one is hardly "outside the galaxy" at that point. The stars are just much further apart.

The term "rim" was usually used without any modifiers. In the first two seasons, there were only two exceptions to this rule:

Considering only Seasons One and Two, then, it would seem that "the Rim" means "the rim of explored space", and Elric was either planning a huge journey or just exaggerating. Note that the term "known space" has been used in other places, such as Infection.

However, Seasons Three and Four completely changed this view.

In Matters of Honor, the season three opener, Morden shows Londo a map of the galaxy, and offers to divide it up between the Centauri and the Shadows. This map was shown three times and each time it was a slightly different map! Presumably the special-effects people are at fault. Here is one version of this map:

Morden's Galactic Map

And in the new "War Room", the wall map shows the entire galaxy, with notes all over the galactic disk.

These maps seemed to imply that the show takes place on a fully galactic scale – despite the fact that Season One and Two indicated that the Narn and Centauri capitals, and Babylon 5 itself, are less than 100 light-years from Earth.

Also, in Voices of Authority, Delenn is re-telling the story of the Old Ones – but this time instead of saying that they "passed beyond the Rim", she explicitly says they "passed beyond the Galactic Rim".

At the same time, JMS began stating that the "rim" is definitely the rim of the galaxy. In a message to Richard Wakefield (20 August 1996), he wrote,

"It's the Rim of the galaxy, and once you come out of hyperspace past the galactic rim, all your points of reference are gone, and getting back is tough, if not impossible . . . and you can't just "keep going" in a straight line in hyperspace, as it's not a one-to-one corrolation to normal space."

Indications of the large scale continued to appear. Deneb was mentioned as a human colony; as mentioned above, this is 1600 LY from Earth. This also made it reasonable to suppose that the mention of Antares (520 LY) in the pilot had not been an error.

But the most important factor was the Shadow War. It is quite clear from all the dialogue between Lorien, the Shadows, the Vorlons, and the other "First Ones" that Lorien wanted them to leave the galaxy, and much of their discussions seem to imply that the First Ones have been shepherding "all the young races in the galaxy", not just in one tiny neighborhood.

For example, in Into the Fire, all the older races are speaking as if the Vorlon-Shadow sphere of influence is the whole galaxy, and the First Ones who became bored of this place went "beyond the rim, to the emptiness which lies between the galaxies". Aside from the oddness of the belief that one would find qualitatively different things outside of our galaxy, this again suggests a large scale to what has been going on. In particular, how can Lorien and Ivanova be sure they have contacted all the First Ones in the galaxy, unless the White Star really did travel the entire width of the galaxy?

***** ***** *****

Compromise: The War Room Map.

Finally, some sort of "compromise scale" emerged. At the World Science Fiction Convention (Labor Day, 1996), Straczynski stated that the "Rim" does indeed refer to the "rim of the galaxy", but that the show's action does not fill up the entire galaxy. Rather, the scope of Babylon 5 is a "pie slice" of the galactic disk.

This was aptly illustrated in And The Rock Cried Out, No Hiding Place. Sheridan and Delenn are studying recent Shadow attacks, and they graphically plot these attacks on the War Room Map. What follows is the War Room Map graphic, with the region they plotted outlined in green:

B5 War Room Wall Map

[Click here for a
high-resolution version of this map.]

This map strongly supports the idea that Babylon 5 takes place in a small segment of the galaxy. As JMS says, a "pie slice".

However, inconsistencies are likely to continue, especially if Straczynski remains as sloppy as he has often been with matters astronomical. For instance, at the end of The Summoning, Lyta Alexander is stressing just how much destruction will be caused by the Vorlon-Shadow War. She exclaims, "Nothing within seventy light-years will survive untouched!"

This is clearly inconsistent with any of the scales we've considered (this tiny region doesn't even include Centauri Prime!) Of course, Lyta was excited – but "seventy" is a fairly precise figure.

Anyway, the "medium scale" seems the best answer, if we are trying to find a "best-fit" theory that results in as few contradictions as possible.....

***** ***** *****

***** ***** *****

Table of interesting stars

Stars listed in this table include: all stars within 11 light-years of Sol; all stars between 11 and 17 LY of Sol except Type M red dwarf stars; all stars with Bayer designation "Epsilon" within 50 LY of Sol; and stars with "Eridani" in their names within 50 LY of Sol.

(The last category is somewhat vague, since there are so many ways to name stars. Past 25 LY, I haven't included stars like "544 Eridani" which generally go by other names. There really isn't much reason to link Babylon 5 to the name "Eridani" in the absence of the letter "Epsilon" anyway.)

Also included: Vega and Deneb; Pi (3) Orionis, which Richard Wakefield has suggested as a possible location for the Orion Colonies; and the Orion Belt Stars (Delta, Epsilon, Zeta) which Chris Russo has suggested may be the origin of the term "Orion Belt Alliance".

I plan some updates to this section soon, plus some discussion of the stars given in the Babylon Project Role-Playing Game.

Right Ascension is in hours east of the standard meridian (close to Alpha Andromedae). Declension is in degrees north/south of the equator. Distance is in light-years from the earth.

Magnitudes under 10 are given. You can see up to 6 or so by eye, and up to 8 or 9 with binoculars. Over 9, you need a telescope, and if you've got one, you have a better star chart than this anyway.

Color gives the spectral class and a rough color translation.

The x , y , z coordinates are in light-years, with Sol at the origin. The z-axis points towards Earth north (Polaris, basically – 23 degrees from Solar north and XX degrees from Galactic north. The x-axis points towards 0 Hours Ascension (Andromeda, and the Capricorn/Pisces border) while the y-axis points towards 6 Hours Right Ascension (Betelgeuse, and the Taurus/Gemini border). These are simply the natural cartesian coordinates which correspond with the spherical (ascension/declination) coordinates.

The Ascension/Declination figures were rounded after the x,y,z were calculated. The x,y,z are considered most useful here, because they make it easy to calculate the distance between any two stars in the table.

Name RtAsc Decl Distance Mag Color x y z
G2 yellow
Proxima Centauri
M5 red dwarf
Alpha Centauri
G2 yellow
K0 orange
Barnard's Star
M5 red dwarf
Wolf 359
M6 red dwarf
BD +36 2147
M2 red dwarf
A1 white
DA white dwarf
UV Ceti (L 726-8)
M5 red dwarf
M5 red dwarf
Ross 154
M4 red dwarf
Ross 248
M6 red dwarf
Epsilon Eridani
K2 orange
Ross 128
M4 red dwarf
Luyten 789-6
M5 red dwarf
M5 red dwarf
Epsilon Indi
K5 orange
61 Cygni
K5 orange
K7 orange
Tau Ceti
G8 yellow
F5 yellow-white
DA white dwarf
Kapteyn's Star
M0 orange-red
van Maanen's Star
DZ7 white dwarf
Luyten 145-141
DQ6 white dwarf
BD 50 1725
K2 orange
Omicron (2) Eridani
40 Eridani
DY Eridani
K1 orange
DA white dwarf
M4 red dwarf
A7 white
70 Ophiuchus
K0 yellow-orange
K5 orange
82 (e) Eridani
G5 yellow
Rho Eridani
K2 orange
K3 orange
Pi (3) Orionis
F6 yellow-white
A0 white
Delta Eridani
K0 yellow-orange
CC Eridani
K7 orange
58 Eridani
G1 yellow
Tau (1) Eridani
F6 yellow-white
Epsilon Ceti
F8 yellow-white
M0 orange-red
Epsilon Reticuli
K2 orange
Epsilon Phoenicis
K0 orange subgiant
Tau (3) Eridani
A4 white
Epsilon Cygni
K0 orange subgiant
M4 red dwarf
Epsilon Scorpii
K2 orange subgiant
68 Eridani
F2 yellow-white
Epsilon Ursa Major
A0 white
Zeta Orionis
09 white giant
B0 white subgiant
Delta Orionis
O9 white giant
B2 white
Epsilon Orionis
B0 white giant
A2 white giant

***** ***** *****

Links to astronomical web-sites

First, some written references:

And some on-line references:

Also, you can buy the Yale Bright Star Catalogue, 5th Edition (Hoffleit, Warren 1991), but it doesn't seem to be online anymore.

Below this point are links I haven't checked recently:

***** ****** ***** *****

Stellar Geography in the Babylon 5 Galaxy / Updated 9 August 2008 by Larry King

Back to the Babylon 5 History Page  BACK

Home to the Science Fiction Timeline Site  HOME

EMAIL   Send email to Larry King