|Cosmology / Powers and Deities / Dramatis Personae /
Rules and Mechanics / Character Creation / Equipment
A crystal sphere (also known as a crystal shell) is a gigantic spherical shell which contains an entire planetary system. Each sphere varies in size but typically they are twice the diameter of the orbit of the planet that is furthest from the sun or planet at the center of the sphere (the system’s primary).
The surface of the sphere is called the “sphere wall” and separates the void of “wildspace” (within the sphere) from the phlogiston (that surrounds and flows outside the sphere). The sphere wall has no gravity and appears to be impossible to damage by any normal or magical means. Openings in the sphere wall called “portals” allow spelljamming ships or wildspace creatures to pass through and enter or exit from a crystal sphere. Portals can spontaneously open and close anywhere on the sphere wall. Magical spells (or magical items that reproduce their effects) can allow a portal to be located. Other magic can open a new portal or collapse an existing one. Ships or creatures passing through a portal when it closes may be cut in two.
Wildspace is considered coterminous with the Material Plane, the crystal shells and the phlogiston. Wildspace is also coexistent with the Ethereal Plane, The Astral Plane, and the Plane of Shadow. Why wildspace touches these planes, while the phlogiston doesn’t is a mystery to planar sages. Wildspace doesn’t have an atmosphere of any kind and is a perfect vacuum.
Gravity is a constant earth-normal powered force. Every object exerts this, but the direction alters according to shape, and only objects of a certain size (generally about 25’ long) exert enough force for a gravity plane to develop. Spherical objects attract objects towards their surfaces uniformly, much as gravity works in our own universe. Objects with a more irregular shape develop a gravitational “plane” which extends along the most convenient axis, generally the longest. This plane works in both direction so that it is possible, for instance, to walk on the bottom of a ship.
Gravity planes exert a slight outward force, so that an object dropped overboard will oscillate across the plane until it settles there, and will then drift slowly outwards from the ship to be eventually expel from the air envelope.
This gravitational plane exerts a “field” which extends to the limit of a body’s air envelope. When two such fields come into conflict the gravitational field of the larger body dominates. This makes it dangerous to be out of pitch or alignment with a larger ship if you enter its gravitational field/air envelope. Specifically, this means that when a ‘jammer enters a planetary atmosphere the planet’s gravity becomes dominant. (You can walk on the bottom of your ship in space, but in a planet’s atmosphere you would fall off and land on your head.)
All bodies of any size carry with them an envelope of air whenever they leave the surface of a planet or other stellar object. Unlike real-world astrophysics, this air envelope is not dispersed by the vacuum of space. These bubbles of air provide breathable atmosphere for varying lengths of time, but 3 months is considered “standard”.