Another new video by Isaac Arthur's YouTube channel today discussing empires where technology has regressed:
Thought I would make a post about geography in sci-fi settings, as this is quite a good thread to just discuss sci-fi generally.
Also I noticed someone in another thread posted a poll where you can vote for you favorite sci-fi setting:
'The Greatest Space Opera Settings'
I hope we hear some more news about that Archetype Entertainment RPG soon, as I really wanna know more about it.
Our Milky Way Galaxy
There are 60 stars, of which 50 are red dwarf stars, in 52 star systems, within 16.3 light years of Earth.
There are approx 2,000 stars, in 1,400 star systems, within 50 light years of Earth.
There are approx 14,600 stars, within 100 light years of Earth.
There are approx 260,000 (visible) stars, within 250 light years of Earth.
There are approx 2,000,000 stars, within 500 light years of Earth.
The galaxy is approximately 170,000-200,000 light years in diameter, counting newly discovered far regions of the disk, and contains 100-400 billion stars.
Most stars seem to have planets, and thus the number of exoplanets is similar to the number of stars, at least.
85% of stars in the Milky Way are red dwarfs (minimum 100 billion).
Planets close to the small red dwarfs may be tidally locked, producing worlds with narrow habitable bands at the terminator.
Most stars, perhaps up to 85%, are binary.
Half of exoplanet host stars are binary.
Around half a dozen new stars are produced per year.
Land or desert worlds may be predominant over water planets, in terms of potential habitable planets, because they have larger habitable zones.
Potentially habitable - pessimistic estimate: 6.4 billion potentially habitable
Potentially habitable - optimistic estimate: 5 trillion potentially habitable
Potentially habitable - middle road estimate: 40-80 billion potentially habitable
Star Trek's Milky Way Galaxy:
The entire United Federation of Planets exists within about a 250 light year diameter sphere of Earth, meaning it is within the small black dot on the map, within the 1500 light year white circle.
It has about 150 members in the 2370s, and more than a thousand planets in total, which may include small colonies, scientific research outposts, military outposts, and planetary Starbases.
The most inhabited known part of the local galaxy surrounds the Rigel system near Klingon space, where many ancient cultures such as the Orions have had colonies for thousands of years.
Within a 500 light year sphere surrounding the Federation lie many empires, including the Klingon Empire, Romulan Star Empire, Cardassian Union, Tholian Assembly and Breen Confederacy
Beyond a 1500 light year sphere that is generally known, the Federation has sent automated probes, to survey systems briefly, probably cataloguing them with numbers like HD 202772A.
Mass Effect's Milky Way Galaxy:
The Mass Effect setting covers a much wider proportion of the Milky Way, but has far less inhabited worlds than Star Trek, because there huge unexplored spaces between mass relays.
Probably vast unexplored voids thousands of light years across are totally unknown, being outside the reach of non-relay FTL travel, creating tiny inhabited pockets around the galaxy.
The political capital of the Mass Effect setting, The Citadel, lies within the Serpent Nebula, and the human homeworld Earth, lies within the Local Cluster, both within civilized Citadel Space.
Several political regions exist, such as the frontier worlds of the Attican Traverse, home to many Prothean Ruins, and the Terminus Systems, which are home to antagonistic governments.
Star Wars's "Galaxy Far Far Away":
It's not generally appreciated that the Star Wars galaxy is somewhat similar to Mass Effect, with huge voids of uncontrolled systems; except here civilized systems lie along hyperspace corridors.
Essentially, the hyperspace corridors are like the Roman Empire's road network, with colonies springing up near where hyperspace travel is safe, and backwaters being further away from them.
There are probably quite a lot of non-member civilizations of the Galactic Republic that lie within what looks like Republic borders on most galactic maps, creating complex political relationships.
This means there may be many abandoned, forgotten, uninhabited, or uncontacted systems off major hyperlanes, and a lot of wild space or unknown regions within the borders of the Republic.