Memory Alpha says two interesting things about The Delphic Expanse in the third season of Star Trek: Enterprise.
Obviously if the Delphic Expanse is almost 2,000 light years in diameter the center of the Delphic Expanse should be almost 1,000 light years inside it. So the center of hte Delphic Expanse can not be about 50 light years from Earth. So it must be the edge of the Delphic expanse which is approximately 50 light yeas from Earth.
"In "The Expanse":
If warp five is the TOS warp scale warp five, it is about 125 times the sped of light. Since there are about 90 days in three months, that would be about 90 X 125 light days, or 11,250 light days, or 30.800821 light years. Or it is about 1/4 year at 125 times the speed of light, or about 31.25 light years.
At TOS warp scale warp factor five, a journey of about 50 light years shuld take about 0.4 years or about 146.1 days.
Later in "The Expanse":
So their route to the Delphic Expanse takes them near Vulcan. The Delphic expanse, being almost 2,000 light years wide, should be beyond Vulcan.
Later they are attacked by Klingons:
Later, enroute to Vulcan:
Since Vulcan is later shown to be 16 to 17 light years from Earth, if the trip from EarIh to Vulcan takes at least 2 days at warp 4.5, warp 4.5 must be slower than 3,104.625 times the speed of light. Warp factor 4.5 in the TOS scale is 91.125 times the speed of light and so it shoudl take at least 61.13 days.
Later, when they reach the Edge of the Delphic Expanse:
Seven weeks or 49 days at TOS scale warp factor five would cover about 6,125 light days or 16.769 light years.
The episode "The Xindi" opens with:
So maybe the edge of the Delphic Expanse is not 50 light years from Earth, but the Xindi council chamber, somewhere within the vast Expanse, is 50 light years from Earth.
A region of space surrounded by "thermobaric clouds" which seem to be very visible in visible light and would cerainly be very visible in some wavelengths of electromagnetic radiaiton should be very spectacular in whatever wavelengths it is visible in if it is only 50 light years away and almost 2,000 light years in diameter.
According to my rough calculations, a sphere 1,000 light years (LY) in diameter would have to be 206,264980 light years distant to have an angular diameter of only one arc second. A sphere 2,000 LY in diameter would have to be 412,529,960 LY distant to have angular diameter of only 1 arc second.
According to my rough calculations, a sphere 1,000 light years (LY) in diameter would have to be 3,437,749.6 light years distant to have an angular diameter of only one arc minute. A sphere 2,000 LY in diameter would have to be 6,875,499.2 LY distant to have angular diameter of only 1 arc minute
The galactic disc of our Milky Way Galaxy is about 1,000 LY thick, and about 100,000 LY in diameter. The Sun is about 25,000 LY from the center of the galaxy. Since the Delphic Expanse and every other world reached in should be within the galactic disc of our Milky Way Galaxy that puts a limit on how far away the expanse can be and how small it can look from Earth.
If the center of the Delphic Expanse could be as far 75,000 LY from Earth, the expanse with a diameter of 1,000 LY would have an angular diameter of 0.76 of a degree, and if it had a diameter of 2,000 LY it would have an angular diameter of 1.52 degree. The Sun and the Moon have angular diameters of about 0.5 of a degree as seen from Earth.
Suppose that the nearer edge of the Delphic Expanse was only 500 LY from Earth. With a diameter of 1,000 LY the central point would be 1,000 LY from Earth. According to my rough calculations the Delphic Expanse would have an angular diameter of about 57.3 degreees as seen from Earth. If the nearer rim of the Delphic Expanse is 500 LY from Earth and it is 2,000LY in diameter, the center of it should be 1,500 LY from Earth, and thus the Delphic expanse shoud have an angular diameter ofabout 76.39 degrees.
Of course if the Delphic Expanse was 1,000 to 2,000 LY from Earth and only a few tens o f LY from earth as is indicated, it would spread out over almost 180 degrees of arc as seen from Earth, close to an entire hemisphere of the sky.
If the thermobaric clouds at the rim of the Delphic Expanse emitted or reflected any wavelengths of electromagnetic radiation (as all normal matter must) the Delphic Expanse should be a very spectacular feature in those wavelengths as seen from Earth.
And if the thermobaric clouds at the rim of the Delphic Expanse were opague to any wavelengths of visible light, (as all nurmal matter must be) our maps of the sky in those wavelengths wuold show a vast back circle in the sky where no light from those wavelengths reached earth.
The thermobaric clouds were depicted as being both visible, and opaque in visible wavelengths of light in the special effects in "The Expanse".
If that is correct in the fictional universe of Star Trek Enterprise. then while the Expanse exists people on Earth will be unable to see a large percentage of the stars which are seen from Earth today. This implies that the Exampse must have reached its size in the era of Enterprise within a century or two, between now in AD 2022 and the year 2153 in an unspecified caendar era.
Or since I believe that Star Trek is in an alternate universe, the Delphic Expanse could have been growing for many centuries before our year of AD 2022, but in Star Trek's universe instead of in our universe.
If TOS is a sequel in the same timeline to Star Trek Enterprise stars mentioned in TOS could have been hidden in the Delpic Expanse up until the Delphic Expanse was destroyed in 2154 and reverted to being normal space, revealling the stars within it.
But all of the proper names of stars mentioned in every era of TOS were given at different dates in Earth history. Some were given by ancient Greeks,and some by medieval Arabs,for example. While the Bayer designations of stars, widely used in various Star Trek productions, were given for northern consellations in 1603 and within a century or two for more southern constellations.
So for each star with an Earth name or Bayer designationin Star Trek, there was a period of centuries or millennia when it must have been visible from Earth, and a period of centuries when it might have been hidden from Earth by the Delphic Expanse.
For example, in "The City on the Edge of Forever" when KIrk was in about the year AD 1930:
The "far left Side in Orion's Belt" is Alnitak.
It has a distance of 1,260 LY plus or minus 180 LY, about 1,080 to 1,440 LY. Anyway, we know that the Delphic Expanse had not yet expanded to cover Orion's betl (if it ever did) by about 1930 in th alernate universe of Star Trek.
I note that if the Delphic Expanise was increasing its radius by more than 1 LY per year, or even in a significant fraction of the speed of light, People on Earth, Vulcan, Andor, and Tellar, for example, should have been very worried by the rate at which it was expanding toward them. The thermobaric clouds could do considerage damage if they hit a world at a signficant fraction of hte speed of light. And after survivors of expeditions into it told of the horrors they experienced there, the expansion of the Expanse would be even more terrifying.
So I find it rather hard to believe that Captain Archer had to be told what the Delphic Expanse was, instead of saying "Oh no! Not the Delphic Expanse!" as soon as it was mentoned to him.
As far as I know, famed science fiction writer Isaac Asimov was the first to use the term "galactography" for the galactic equivalent of Earthly geography, in his novel The Stars Like Dust (1951). And naturally, he made an error in galactography in it, depicting the Horsehead Nebula as being many times larger than it actually is.
And it seems like an interesting problem in galactography to figure out where the Delphic Expanse could be be in space relative to Earth and to other stars mentioned in various Star Trek productions.
The Delphic Expanse was a region of space approximately fifty light years away from Earth. (ENT: "The Expanse")
Nearly two thousand light years across, the Expanse was riddled with a web of dangerous spatial anomalies and was surrounded by a dense layer of thermobaric clouds, which made navigation extremely hazardous for starships. In some regions of the Expanse, the laws of physics did not function reliably. Artificially created by transdimensional beings using a vast number of massive spheres, the Delphic Expanse ceased to exist in 2154, when the Earth starship Enterprise NX-01 destroyed them. (ENT: "The Expanse", "The Xindi", "Zero Hour")
Obviously if the Delphic Expanse is almost 2,000 light years in diameter the center of the Delphic Expanse should be almost 1,000 light years inside it. So the center of hte Delphic Expanse can not be about 50 light years from Earth. So it must be the edge of the Delphic expanse which is approximately 50 light yeas from Earth.
"In "The Expanse":
SOVAL: Do you know where these co-ordinates he gave you are?
ARCHER: At warp five, about a three month trip.
SOVAL: They're inside the Delphic Expanse.
ARCHER: What's that?
SOVAL: A region of space nearly two thousand light years across. Vulcan ships have entered it, but only a few have returned.
ARCHER: Sounds like your talking about the Bermuda Triangle.
SOVAL: There has been reports of fierce and dangerous species, unexplained anomalies. In some regions, even the laws of physics don't apply. Twenty years ago, a Klingon vessel emerged from the Expanse. Every crewmen on board has been anatomically inverted, their bodies splayed open, and they were still alive. You'd be more than foolish to pursue this course of action.
If warp five is the TOS warp scale warp five, it is about 125 times the sped of light. Since there are about 90 days in three months, that would be about 90 X 125 light days, or 11,250 light days, or 30.800821 light years. Or it is about 1/4 year at 125 times the speed of light, or about 31.25 light years.
At TOS warp scale warp factor five, a journey of about 50 light years shuld take about 0.4 years or about 146.1 days.
Later in "The Expanse":
ARCHER: Soval agreed to let us take her back to Vulcan if it's all right with you.
FORREST: It's not that far out of your way. How's that last refit team doing?
So their route to the Delphic Expanse takes them near Vulcan. The Delphic expanse, being almost 2,000 light years wide, should be beyond Vulcan.
Later they are attacked by Klingons:
ARCHER: Go to four five. If we can make it to Vulcan space before they get their engines back, they'll think twice about giving us any more trouble.
Later, enroute to Vulcan:
T'POL: Ensign Mayweather says we're two days from Vulcan.
Since Vulcan is later shown to be 16 to 17 light years from Earth, if the trip from EarIh to Vulcan takes at least 2 days at warp 4.5, warp 4.5 must be slower than 3,104.625 times the speed of light. Warp factor 4.5 in the TOS scale is 91.125 times the speed of light and so it shoudl take at least 61.13 days.
Later, when they reach the Edge of the Delphic Expanse:
Captain's starlog, supplemental. We've been travelling at warp five for seven weeks. The crew is anxious to begin our mission.
Seven weeks or 49 days at TOS scale warp factor five would cover about 6,125 light days or 16.769 light years.
The episode "The Xindi" opens with:
HUMANOID: It could simply be a coincidence.
REPTILIAN: You're being naive. Their planet is fifty light years away. It is not a coincidence.
So maybe the edge of the Delphic Expanse is not 50 light years from Earth, but the Xindi council chamber, somewhere within the vast Expanse, is 50 light years from Earth.
A region of space surrounded by "thermobaric clouds" which seem to be very visible in visible light and would cerainly be very visible in some wavelengths of electromagnetic radiaiton should be very spectacular in whatever wavelengths it is visible in if it is only 50 light years away and almost 2,000 light years in diameter.
According to my rough calculations, a sphere 1,000 light years (LY) in diameter would have to be 206,264980 light years distant to have an angular diameter of only one arc second. A sphere 2,000 LY in diameter would have to be 412,529,960 LY distant to have angular diameter of only 1 arc second.
According to my rough calculations, a sphere 1,000 light years (LY) in diameter would have to be 3,437,749.6 light years distant to have an angular diameter of only one arc minute. A sphere 2,000 LY in diameter would have to be 6,875,499.2 LY distant to have angular diameter of only 1 arc minute
The galactic disc of our Milky Way Galaxy is about 1,000 LY thick, and about 100,000 LY in diameter. The Sun is about 25,000 LY from the center of the galaxy. Since the Delphic Expanse and every other world reached in should be within the galactic disc of our Milky Way Galaxy that puts a limit on how far away the expanse can be and how small it can look from Earth.
If the center of the Delphic Expanse could be as far 75,000 LY from Earth, the expanse with a diameter of 1,000 LY would have an angular diameter of 0.76 of a degree, and if it had a diameter of 2,000 LY it would have an angular diameter of 1.52 degree. The Sun and the Moon have angular diameters of about 0.5 of a degree as seen from Earth.
Suppose that the nearer edge of the Delphic Expanse was only 500 LY from Earth. With a diameter of 1,000 LY the central point would be 1,000 LY from Earth. According to my rough calculations the Delphic Expanse would have an angular diameter of about 57.3 degreees as seen from Earth. If the nearer rim of the Delphic Expanse is 500 LY from Earth and it is 2,000LY in diameter, the center of it should be 1,500 LY from Earth, and thus the Delphic expanse shoud have an angular diameter ofabout 76.39 degrees.
Of course if the Delphic Expanse was 1,000 to 2,000 LY from Earth and only a few tens o f LY from earth as is indicated, it would spread out over almost 180 degrees of arc as seen from Earth, close to an entire hemisphere of the sky.
If the thermobaric clouds at the rim of the Delphic Expanse emitted or reflected any wavelengths of electromagnetic radiation (as all normal matter must) the Delphic Expanse should be a very spectacular feature in those wavelengths as seen from Earth.
And if the thermobaric clouds at the rim of the Delphic Expanse were opague to any wavelengths of visible light, (as all nurmal matter must be) our maps of the sky in those wavelengths wuold show a vast back circle in the sky where no light from those wavelengths reached earth.
The thermobaric clouds were depicted as being both visible, and opaque in visible wavelengths of light in the special effects in "The Expanse".
If that is correct in the fictional universe of Star Trek Enterprise. then while the Expanse exists people on Earth will be unable to see a large percentage of the stars which are seen from Earth today. This implies that the Exampse must have reached its size in the era of Enterprise within a century or two, between now in AD 2022 and the year 2153 in an unspecified caendar era.
Or since I believe that Star Trek is in an alternate universe, the Delphic Expanse could have been growing for many centuries before our year of AD 2022, but in Star Trek's universe instead of in our universe.
If TOS is a sequel in the same timeline to Star Trek Enterprise stars mentioned in TOS could have been hidden in the Delpic Expanse up until the Delphic Expanse was destroyed in 2154 and reverted to being normal space, revealling the stars within it.
But all of the proper names of stars mentioned in every era of TOS were given at different dates in Earth history. Some were given by ancient Greeks,and some by medieval Arabs,for example. While the Bayer designations of stars, widely used in various Star Trek productions, were given for northern consellations in 1603 and within a century or two for more southern constellations.
So for each star with an Earth name or Bayer designationin Star Trek, there was a period of centuries or millennia when it must have been visible from Earth, and a period of centuries when it might have been hidden from Earth by the Delphic Expanse.
For example, in "The City on the Edge of Forever" when KIrk was in about the year AD 1930:
KIRK: We served together.
EDITH: And you don't want to talk about it? Why? Did you do something wrong? Are you afraid of something? Whatever it is, let me help.
KIRK: Let me help. A hundred years or so from now, I believe, a famous novelist will write a classic using that theme. He'll recommend those three words even over I love you.
EDITH: Centuries from now? Who is he? Where does he come from er, where will he come from?
KIRK: Silly question. Want to hear a silly answer?
EDITH: Yes.
KIRK: A planet circling that far left star in Orion's belt. See?
The "far left Side in Orion's Belt" is Alnitak.
Alnitak is a triple star system in the constellation of Orion. It has the designations ζ Orionis, which is Latinised to Zeta Orionis and abbreviated Zeta Ori or ζ Ori, and 50 Orionis, abbreviated 50 Ori. The system is located at a distance of several hundred parsecs from the Sun and is one of the three main stars of Orion's Belt along with Alnilam and Mintaka.
It has a distance of 1,260 LY plus or minus 180 LY, about 1,080 to 1,440 LY. Anyway, we know that the Delphic Expanse had not yet expanded to cover Orion's betl (if it ever did) by about 1930 in th alernate universe of Star Trek.
I note that if the Delphic Expanise was increasing its radius by more than 1 LY per year, or even in a significant fraction of the speed of light, People on Earth, Vulcan, Andor, and Tellar, for example, should have been very worried by the rate at which it was expanding toward them. The thermobaric clouds could do considerage damage if they hit a world at a signficant fraction of hte speed of light. And after survivors of expeditions into it told of the horrors they experienced there, the expansion of the Expanse would be even more terrifying.
So I find it rather hard to believe that Captain Archer had to be told what the Delphic Expanse was, instead of saying "Oh no! Not the Delphic Expanse!" as soon as it was mentoned to him.
As far as I know, famed science fiction writer Isaac Asimov was the first to use the term "galactography" for the galactic equivalent of Earthly geography, in his novel The Stars Like Dust (1951). And naturally, he made an error in galactography in it, depicting the Horsehead Nebula as being many times larger than it actually is.
And it seems like an interesting problem in galactography to figure out where the Delphic Expanse could be be in space relative to Earth and to other stars mentioned in various Star Trek productions.