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Astronomy in Pournelle's Future History

• Galactic Map
• Map of Known Stars
• Map from Earth to Sparta (with travel times)
• Map of objects near the Coal Sack
• New Washington and the Size of the Empire
• Appendix: Astronomy Books and Web Sites

Galactic Map

This map of our galaxy (the "Milky Way") is based on the one in the 1994 Cambridge Atlas of Astronomy. All star positions are taken from the Gliese Catalog of Nearby Stars and various other catalogs.

Very few real astronomical objects are mentioned in Pournelle's Future History series:

• Earth, Luna, and Ceres are the only settlements mentioned in the Solar system. The Grand Senate and the headquarters of the CoDominium Fleet were on Luna in the 2100's. Ceres Base is a small military port-of-call, burrowed into the asteroid. (References in FL 210, 216, and "He Fell into a Dark Hole" 16-19, 37. For details on book abbreviations and page numbers, see the Bibliography.)

• Meiji is mentioned in "He Fell into a Dark Hole", but this story is not consistent on what its star is. On page 24 it is located at 82 Eridani, while on pages 29 and 48 it is in the 81 Eridani system. I have chosen 82 Eridani as the proper location, for the following reasons:
  • 82 Eridani is a nearby star (20.44 light-years away), while 81 Eridani is much further away. We know Meiji was settled very early during the Great Exodus, and is only two jumps from Sol. So this distance makes sense.
  • 82 Eridani is a G5 V star, very similar to our sun (which is G2 V). This makes it a logical place for Meiji, since that colony is a fairly pleasant planet.

  82 Eridani is located at 3:19:56 hrs Rt Asc, -43.070° Dec, and has a visual magnitude of 4.27. In galactic coordinates it is at longitude 250.28° and latitude -55.814°. It is 20.44 light-years (6.267 parsecs) from Earth.

  On the map above, the dot representing Sol is thick enough that it includes 82 Eridani as well.

• Crucis is the home of the Blaine family from the 27th century until the 31st. However, this planet never enters into any stories directly. It is presumably a star in the constellation Crux (the Southern Cross). But which star?

  Alpha Crucis is also named Acrux. And we know that Roderick Harold, Lord Blaine, the heir to the Marquis of Crucis, holds the title "Earl of Acrux" (Hand 58). So it is very possible that "Crucis Court" is on a planet in the Acrux System. But we don't know that for certain; it's possible that the title "Earl of Acrux" is like the title "Prince of Wales" – in other words, it might refer to a different star than the actual home of the Blaine family.

  Alpha Crucis can be seen at 12:26:36 hrs Rt Asc, -63.10° Dec, and has a visual magnitude of 1.33. In galactic coordinates it is at longitude 300.47° and latitude -0.609°. It is located around 400 light-years from here. It is a double star. Alpha Crucis A is a B1 V star, blue-white and extremely bright, but not especially large.

  This seems a plausible choice for Crucis' location. Stories set in the Trans-Coalsack Sector often refer to the majority of the Empire being on the other side of the Coal Sack, and usually Crucis is referred to specifically. Alpha Crucis is on our side of the Coal Sack but not very far from it. (Of course, a lot of stars in Crux can make this boast!) Also, Crucis is not explicitly mentioned in any stories until the Secession Wars, and House Blaine probably dates from this era (see the Timeline for details.) So its distance is plausible; we know humanity reached the Coal Sack by 2450.

  On the other hand, "Crucis Sector" is mentioned in the 2100's, and includes Dayan and other 21st Century worlds. We know little about what determines a "sector". But in any event, there is clearly a Blaine family holding the Acrux system, whether or not that is "Crucis" itself.

• New Chicago is located at "Beta Hortensis" or "Beta Hortensi" (Mote 3, Reflex 16). There is no constellation today with a name similar to this. This isn't surprising, because New Chicago would not be visible from Earth. It may be behind the Coal Sack, and even if it's not, an F9 star near the Coal Sack would be invisible to all but our best telescopes.

• The Coal Sack itself is a dark nebula, centered at 12:50 hrs Rt Asc, -63° Dec, and stretching across 6° of the southern sky. It spans from Galactic Longitude 300° to 306° and Galactic Latitude -4° to 2° (very close to the galactic plane). The Coal Sack is about 550 light-years from Earth. Niven and Pournelle put Murcheson's Eye behind the Coal Sack because they wanted a fairly nearby red giant star, didn't believe any known giants were close enough, and so imagined a red giant just behind the Coal Sack that would be relatively close to us but invisible from the Earth. However, the most recent figures suggest that Antares is probably about the same distance from us as the Coal Sack. It is possible that when Mote was written, the authors believed Antares to be farther than it is, or the Coal Sack to be nearer than it is.

Galactic latitude and longitude give an object's position from Earth's perspective. The core of the galaxy is at 0° latitude and 0° longitude, at a distance of around 30000 LY. Due "north" along the galactic axis is latitude +90°.

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. As David Gerrold once commented, trying to pinpoint the precise "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.

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. If you're interested in the details, take a look at Binney and Tremaine's Galactic Dynamics.

Map of Known Stars

This map shows Sol, 82 Eridani (Meiji), Acrux (Crucis?), and the Coal Sack. Their locations were already described above. The map's scale is correct with regard to these objects.

The additional stars on this map are not identified with any stars known today:

• Murcheson's Eye is behind the Coal Sack, only two light-years from the Coal Sack itself (Mote 155). Note that the Coal Sack's border is probably quite imprecise from close-up, though Dr. Buckman doubtless has a rigorous definition of where it "begins". The Coal Sack itself is about 60 light-years "wide" (along galactic longitude and latitude). Mote 47 and Motelight 115 make it about 30 light-years thick (i.e., in the dimension we can't see from Earth).

• The Mote is very close to the Eye; the precise distance of one-third of a light year is given in "Building the Mote in God's Eye", on page 129 of A Step Farther Out.

• The New Caledonia system, which contains both New Scotland and New Ireland, is 35 light-years from the Mote. (Mote 42, 47, 105.)

• New Chicago is around 65 light-years (20 parsecs) from New Cal.

• Maxroy's Purchase is close to the Coal Sack, on "our side" or near the edge. Hand 9 makes it clear that a direct line from Maxroy's Purchase to the Mote goes throught the Coal Sack itself.

These distances aren't enough to triangulate the precise positions of these stars. But using these distances and the map in Gripping Hand, they can be plotted within a reasonable degree of error. Note that I have, for simplicity, assumed that these lie somewhat in a plane; by letting them move towards and away from the viewer (galactic north and south) the apparent map-distances could be reduced.

The "CoDominium 2090" border reflects the 200 light-year diameter of the CD mentioned on FL 297. More on this later.

Map from Earth to Sparta

This map shows a closer view of the neighborhood of Sol. The scale of this map is speculation, other than the distance from Sol to 82 Eridani.

The tricky part lies in the fact that Alderson jumps are of varying size. But Sparta is six jumps and six months from Earth, while Tanith is one jump and one month from Earth (GTS 149, PS 166). Moreover, Meiji is 20 LY from Earth, and (by the ideal route) only two jumps. As a reference for comparison, we may note that (elsewhere in the galaxy) Prince Samual's World and Makassar are 12 LY apart and only one jump apart.

So I've allowed around 10 to 15 LY to each jump on this map, although this is clearly not going to be always the case.

Green lines represent single jumps. Blue lines represent one or more jumps: this simply means there is a fairly direct "route" between these two stars, but the number of jumps is unknown.

The usual route from Meiji to Earth involves several jumps and passes by Colby. The "direct" route involved exactly two jumps, stopping off at A-7820 (presumably a red dwarf or other uninteresting star) on the way. ("He Fell into a Dark Hole" 18, 21, 24.)

The stops from Earth to Sparta are explicitly given on GTS 149.

Tanith is on the standard routes from Sparta to Earth and from Sparta to New Washington. (See below for more details on New Washington's location). Coming from the Earth, the worlds of Haven, Frystaat, and Dayan are "beyond Sparta". Haven is one of the farthest worlds in the 21st Century (and remains un-re-discovered in the 3040's). (GTS 94, 149) Crucis is probably also in this direction, since Dayan (Dyan) is in Crucis Sector (WWI 362).

Travel times during the 21st Century:

• The trip from Sparta to New Washington is 9 months per PS 166; it's also given as 8 or 5 months (GTS 95, PS 8).
• From Tanith to New Washington is 4 months (PS 166).
• Since the Sparta-New Washington route goes via Tanith, we can subtract and get about 5 months for the Tanith-Sparta journey (though travel from one Alderson point to another in the same system won't be exactly the same as travel from the point to/from the gravity well of the inner system).
• From Earth to Sparta is given as 6 months on PS 166; alternate times are 7 or 8 months (GTS 71, PS 8).
• Again we can subtract (as the Earth-Sparta route is via Tanith) and see that it's about one month from Tanith to Earth.
• Going from Earth to New Washington would take 5 months if it were done via Tanith, but the sources don't say this is necessary, so it could be as short as 3 months if New Washington is in the other direction.

The following worlds are mentioned in Pournelle's future history, but not enough information is given to determine their location:

• Thurstone (the planet containing the nations of Santiago and New Aberdeen) is 65 light-years and 3 months from Earth (PM 134-5).
• Arrarat is also 65 light-years from Earth, and is in Crucis Sector (FL 53, 125).
• During the Secession Wars, the trip from Tanith to Sparta was long and dangerous, but Gaea was more easily reachable from Tanith and is therefore probably close to it (WWII 219). However, WWII 182 seems to imply that Sol, Sparta, and Nuliajuk are near each other and Tanith is distant from these three; this doesn't square well with Tanith being on the route from Sol to Sparta.
• Wayforth Station is a stopping point on the way to Haven and is in the "Tanith Sector" (WWCD 7, 11).

Map of objects near the Coal Sack

This map is a close-up of the Trans-Coalsack Sector and the region nearby. The Locations of the Mote, Murcheson's Eye, New Chicago, Maxroy's Purchase, and the New Caledonia system (which includes New Scotland and New Ireland) were discussed above.

The shape of the Coal Sack in this drawing, as well as the location of the "curdle", are based on the map in The Gripping Hand.

As in the previous map, green lines represent single jumps and blue lines are more indirect routes. In particular, the route from New Chicago to New Cal involves several jumps (Mote 36).

Additional stars:

• MGC-R-31 is a red dwarf 8 light-years from the Mote. MGC-R-60 is another red dwarf which is almost certainly closer to the Eye. (Presumably "MGC" is Murcheson's General Catalogue.....)

• Maxroy's Purchase is on the other side of the Coal Sack from the Mote. The route to New Utah passes by two red dwarfs and a "class E" sun. Heading back towards the Empire from Maxroy one encounters Darwin, then eventually Xanadu and Tabletop (which are CoDominium worlds near the center of the Empire). (Hand 12, 21.)

• Harlequin, an extremely primitive world, lies past New Chicago, since Sally Fowler stopped here on her way to investigate Harlequin.

• There is a red dwarf 0.4 light-years from New Chicago which Rod Blaine used to stage his attack ("Reflex" 16).

• Levant, Crucis, and Sparta are back towards the heart of the Empire. Some texts seem to imply that Crucis and Levant aren't far from here. (See "Motelight" 118, Hand 139.)

• One reference suggests that New Washington is only one jump from New Chicago, but other texts make this seem unlikely. See below for details.

Also, the flare star EST 1310 is located "Galactic South of the Coal Sack", but no specific distance is given. (WWII 177, 197, 213.) It's not on this map, since galactic north and south are towards and away from the viewer from this perspective.

New Washington and the Size of the Empire

The extent of human settlement in the galaxy grows as time progresses, at least up to the end of the First Empire. The Second Empire seems to be merely retaking old territory; they may not be founding new colonies at all.

In the 2080's, the CoDominium is 200 light-years in diameter, and contains 70 human colonies, according to FL 297. There are variations on these figures: GTS 248 counts "more than 100" human colonies, while PS 2 counts "more than 130" and the Mote prologue claims "200" by the end of the century.

In 3017, the Second Empire includes at least the entire 600 light-years from Earth to the Coal Sack. Mote 458 says that "everyone within two hundred parsecs wanted a seat on the Commission." In 3029, Horvath says the Empire contains "fifteen million cubic parsecs", which makes it about 1000 light-years in diameter. (Mote prologue.)

Horvath also mentions that the Empire contains 200 worlds in the year 3029. In 3046, Jennifer Banda says the Blaine Institute has specimens from 400 Imperial worlds and 30 Outie worlds. Also in 3046, Renner refers "1000 worlds", but this may be an exaggeration. (Mote prologue; Hand 73, 83.)

Despite slight variations, these numbers are roughly consistent. And all the planets mentioned during the 21st century are relatively close to Earth... with one possible exception: New Washington.

• On GTS 249, New Washington is said to be 20 light-years from Sparta. This is quite close. Indeed, as the route from Sparta to New Washington passes by Tanith (PS 166), we would expect that New Washington is even closer than this to Tanith, and probably to Earth as well.

• The diameter of the CD is 200 light-years (see above). New Washington is mentioned as a particularly distant world. So we might expect it to be between 50 and 100 light-years from Earth.

• On FL 432, New Washington is explicitly said to be 100 parsecs from Earth. This is around 330 light-years, which is farther than any CD world ought to be.

• Moreover, on Hand 366, we are told that before the assault on New Chicago in 3016, the Fleet gathered at New Washington "before the final jump". This would put New Washington one jump from New Chicago. But New Chicago is in the Trans-Coalsack Sector, 65 light-years from New Cal – which is itself 37 light-years behind the Coal Sack. The Coal Sack is around 550 light-years from Earth. So New Chicago is between 500 and 650 light-years from Earth. Although no upper boundary for an Alderson path is stated, there is no precedent in these tales for a single path with length anything near 200 light-years, so this would force New Washington even further out.

I don't have a good resolution to this problem. I tend to disbelieve the "one jump from New Chicago" version, however. Perhaps the fleet assembled at New Washington before the final series of jumps?

Finally, Prince Samual's World and Makassar are not on any of these maps. Their location is never specified. All that we know is that they are very far from the Trans-Coalsack Sector, they are 12 LY from each other, and during the 31st Century the trip between them takes about 46 days and involves one jump. (KDS 155, 255, 305.)

Appendix: Astronomy Books and Web Sites

First, some written references:

• Peter van de Kamp, "The Nearby Stars", Annual Review of Astronomy and Astrophysics, Vol. 9, 1971, pp. 103-126.

• W. Gliese, "Catalogue of Nearby Stars", Veroeffentlichungen des Astronomischen Rechen-Instituts Heidelberg, No. 22, 1969.

• W. Gliese and H. Jahreiss, Third Catalogue of Nearby Stars, in preparation. See web-site below.

• Ian Ridpath, Norton's 2000.0, Longman, 1989.

• Cambridge Atlas of Astronomy, Cambridge University Press, 1994. This contains the map at the top of this page and many beautiful illustrations.

• James Binney and Scott Tremaine, Galactic Dynamics, Princeton University Press, 1987. If you would like a description of the motion of stars in our galaxy, this is your source! Some background in math and physics won't hurt (this is a standard first-year grad school text).

And some on-line references:

• Aladin Sky Atlas
• SIMBAD Astronomical Database
• Nearby Stars, 3rd Edition (Gliese, Jahreiss 1991)
• Star Catalogue links by Nyrath -- includes zipped versions of the Gliese data!
• 3-D Star Maps by Nyrath
• Stars in various science fiction works -- again by Nyrath the Nearly-Wise!
• David Nash's HYG Database
• More astronomy links from the University of Strasbourg

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

Jerry Pournelle's Future History . . . . . Star-Map
Updated 19 March 2004 by Larry King

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