Well, this is interesting. There are actually only 19 spheres listed here, some of the articles are actually planets within these spheres. Here are some details on the 19.
1. Aebrynis-Space (Birthright)
Aebrynis is considered something of a backwater, and has few sites of interest. Beyond that, nothing is known about this sphere.
2. Ash-Space
A large system with ten worlds.
Human refuges settled in a number peaceful colonies within the Ashspace system. Leaving war and its atrocities behind. Successive waves of conquerors have invaded the system; Orcs, Ogres, Beholders, Mind Flayers, and finally Gagwallers. These waves of conquerors have fought a series of interplanetary wars for control of this Crystal Shell. Settlements on two worlds have been reduced to dust and almost all traces of the human colonies have been lost.
3. Astromundi Cluster
This is the big one, essentially the "default" sphere for Spelljammer.
The Astromundi Cluster is unique among crystal spheres in that it lacks planetary-sized masses. Instead, the Cluster is filled with planetoids, asteroid belts, man-made habitats and other interesting features. Isolated and secluded, the Cluster is not a forgiving place; ships that enter Clusterspace sometimes never leave, unable to escape from a crystal sphere that was more than willing to let them in. On top of that, there are a number of different power groups within the Astromundi Cluster, each with its own goals and means of achieving its ends.
4. Athas-Sphere
It's most famous in Spelljamming for essentially being unreachable.
The crystal sphere of Athas is located in an isolated and distant part of the Phlogiston, far from the spacelanes of the Known Spheres. As far as is known, the current inhabitants of Athas have little knowledge of spelljamming, although it is possible that some closely guarded library maintained by one of the sorcerer-kings conceals some ancient tome that details the basic concepts of wildspace.[1]
What is known is that the crystal sphere surrounding Athas is impenetrable.[2] It is either impervious to magic or it does not feature any natural portals: either way, spelljammers are unable to travel through the crystal shell, either into the Flow or from the Flow into the wildspace of Athas.
5. Dark-Space
Darkspace is a long dead crystal sphere dominated by the vampire T'Laan.
Darkspace is a sunless, shadowy void that has been dead for a long time. Dominated by the enormous husk of a dead sun, the crystal sphere is littered with chunks of debris of an unknown nature, some of which are the size of moons and small planets, and lying in various orbits around the dark sun. Unlike wildspace within a normal sphere which usually maintains a constant temperature, the void of Darkspace is always cold with strong, biting winds. Although life does not occur naturally in Darkspace, hordes of undead roam the great hunks of rock floating in Darkspace.
6. Elysak
A small system of five planets orbiting a hot orange sun.
The second planet, Ippruk, dwarves, elves, humans, orcs and ogres live in a series of bronze-age civilizations. Spelljamming is little known in the system.
7. Faerie-Space
Faeriespace is a beautiful, exotic sphere full of wonder and new experiences. The underlying magical quality of Faeriespace ensures this strange, alien sphere instills in its visitors a constant sense of astonishment.
Faeriespace has a unique society in that the entire solar system is one large community. Despite the wide variety of races and cultures that exist there, all are peaceful and unified. The common tongue has no word for this unusual state of peacefull co-existence, but in the faerie tongue it is called shrakma. The word shrakma actually has two totally contradictory meanings. In one sense, it refers to the unifying force in Faeriespace that ties its people together as one. But it can also refer to the carefree, chaotic spirit of the inhabitants that make up this mystical, faerie sphere.
Dominating the crystal sphere is an unimaginably huge tree that is impossible to see in its entirety. The branches and leaves of the tree are so enormous that they have their own gravity and maintain a virtually inexhaustible air supply. Hanging from certain branches around the tree are its strange fruit: giant, burning suns. Together they provide the entire sphere with brilliant illumination. Supported on the branches of the tree are eight planets; exactly half the number of suns on the tree.
The leaves of the tree are constantly shifting and changing position. In this manner, they selectively block the light of the many suns during certain times, effectively creating night and day on the various planets. Where the trunk of the mammoth tree splits into three main branches lies a vast, beautiful city, named Armon, the capital of Faeriespace and home of Aelivere, the One King.
8. Glowrings
The Glowrings Sphere is a crystal sphere invaded by the scro during the Second Unhuman War.
9. Great-Space
Greatspace is a scientifically advanced crystal sphere whose inhabitants (known as Citizens) are intellectually and aesthetically inclined, and are prone to rely on science rather than magic. Despite their great reverence for the Olympians (the gods of the Greek Pantheon), the people of Greatspace regard legends and mystical tales of times past as of little importance.[3]
Greatspace as a whole is ruled by a single government. Due to the vast distances between planets and the differences between the various cultures within the sphere, the government is loosely organised and rules with a light touch. For as long as most people can remember, House Shambrath of the planet Thesalys has governed Greatspace.
10. Grey-Space (Greyhawk)
Greyspace is one of the largest crystal spheres yet discovered, with a diameter of 16,000 million miles (25,750 million kilometres).[4] It also features perhaps the widest variety in planetary shapes and types, ranging from standard spherical planets to elongated, irregular and flat worlds, as well as belt and cluster formations.[5] The wildspace of Greyspace is cooler than that of Realmspace, but not as cool as that of Krynnspace. Most sages believe this means Greyspace is younger than Realmspace.
11. Hero-Space
Herospace is a crystal sphere controlled by the Rational Order of Magistrates, whose headquarters are located on the moon Borden, which is in orbit around the world Ge'Neva.
Herospace is a unique sphere in that it has nine separate suns. Each sun is much smaller than a typical sun from a standard sphere, and only has a single planet revolving around it. The planets each represent one distinct alignment, and with few exceptions, individuals may only live on the planet that corresponds to their personal alignment.
To live in Herospace, an individual must prove to the Rational Order of Magistrates that they are above the common man. Entry into Herospace is controlled by the Order, who retain the sole right to judge those who hope to call it home.
12. Home-Space
Not much is known about Homespace, except that it is the home sphere of Chila Irontooth of the Land of Kasros.
13. Korv-Space
Korvspace is a crystal sphere dominated by the Korvadan Empire from the planet Korvada.
Korvada is the home-world of the Korvadan Empire, a predominantly elven civilization that has governed the inner system of Korvspace for the last 200 years.[3][2] Korvada has two moons, named Xbal and Anque.
14. Krynn-Space (Dragonlance)
Of all the Known Spheres, Krynnspace is considered the most primitive and pristine by spelljamming travelers.[4] At roughly 8,000 million miles in diameter, Krynnspace is considerably larger than Realmspace,[4] and is also notably colder than other known spheres and as such is plagued by small lethal clouds of freezing vapour.
15. Mystara-Space (Mystara)
Mystaraspace is relatively unknown among the cultures of the greater spelljamming universe, but is well known amongst planar travellers.[3] The wildspace of the sphere is remarkably cold, and has been compared to an arctic glacier on a long winters night.[4] To avoid cold related injuries, spelljamming vessels will need to be heated and crew members will need to wear heavy winter clothing.
Additionally, entering Mystaraspace causes the gravity plane of a spelljamming vessel to malfunction. Whereas a normally functioning gravity plane attracts objects on both side of the plane, in Mystaraspace only the 'upper' side will attract objects, whereas the 'bottom' side of the plane will actively repel objects. This may cause accidents and injuries on vessels with non-standard gravity planes, such as the illithid nautiloid, especially if the crew are unaware of the effects of entering Mystaraspace.[5]
As a consequence of the altered gravity plane, the ships' air envelope is actively being repelled by the 'negative' gravity, causing air to be discharged into wildspace, This will deplete a spelljammers air envelope at a much faster rate than normal. Vessels will need to be made airtight to minimise this problem.
16. Pirtel
Pirtel is a frigid, sparsely inhabited crystal sphere that was named for the explorer, Anthonius Pirtel, also known as the Ice Mage.
Century is a frozen ball of ice and rock which orbits the sun once every 100 years. This frigid world is tidally-locked in orbit around the sun; one side perpetually facing the light of the sun and the other the dark of wildspace. From orbit, the sunward side is scoured by huge snowstorms which conceal entire mountain ranges from sight, while the dark side is deceptively featureless; a pale grey-white against a backdrop of stars.
In the Lands of Gray Ice, where the light and dark sides merge, an on-going war persists between human barbarians and the frost elves. Once upon a time, the elves were known by another name, now all but forgotten except by a few wizened human shamans: once they were known as Drow. Hundreds of years ago, during the first Unhuman War, the Elven Imperial Fleet cornered a large Drow fleet near Century. Rather than surrender, the drow chose to crash their fleet on the frozen world, vowing to one day return to the skies. Nearly half the fleet perished in the bitter cold of Century's dark side, but those that survived began to adapt to their new home, becoming the frost elves.
17. Realm-Space
Realmspace, known as the Sea of Night by the natives of Toril,[4] is about 6,400 million miles (10,300 million kilometres) in diameter.[5] Its wildspace is slightly warmer than that of Greyspace, to the point where spacefarers can wear light garments and outfits suitable for summer weather.[6] Many sages believe that the older a crystal sphere is, the warmer it is. This would mean that Realmspace is the oldest crystal sphere yet encountered.
18. Refuge
Refuge is a small crystal sphere located close to Realmspace that is controlled by the Arcane. It serves as a way-station for beleaguered spacefarers, where aid and supplies can be found. Refuge’s large sun has only one planet, its' single moon Refuge, and a small outer planetoid.
19. Vodoni-Space
Vodonispace is the principal crystal sphere of the Vodoni Empire and is ruled with an iron fist by the Emperor Vulkaran[4] from the Imperial Palace on the planet Vulkarus.
For hundreds of years, Vodonispace has been at the heart of an ever expanding web of conquest as the tyrant, Vulkaran the Dark, has slowly worked his way across the infinite vastness of space. The might of the Vodoni Empire is unmatched in the universe, and the Emperor currently rules Twelve Spheres of Known Space the old fashioned way: kill your enemies before they kill you; crush all resistance before it grows; mercy is for the weak and gutless; and the end always justifies the means. Needless to say, the Vodoni aren’t the happiest people in the universe, and neither are the inhabitants of the eleven other spheres within the Empire. Vulkaran rules with an iron fist, supported by his merciless Vodoni enforcers, who carry out his wishes without question. These horrible, blood-thirsty lycanthropic warriors are the scourge of the Twelve Spheres and have no respect for any living creature.
