Astral Plane

The Astral Plane, also known as the Astral Sea, was one of the planes of existence in various models of cosmology.

Geography
"It is the space between everything. It is the road that goes everywhere. It is where you are when you aren't anywhere else."

- Manual of the Planes

The Astral could be reached from almost any point in a Prime Material plane or first layer of any Outer plane by spell, psionic ability, or device. It was described as a barren place of other-dimensional nothingness extending in all directions. What little solid substance that floated in the bright, gray void was typically chunks of matter broken off from their original plane. The Astral had no gravity but objects did retain their mass so you could throw small items or push off from large objects to move in the weightless environment.

Time in the Astral flowed at the same rate on a Prime Material plane but the effects of time were slowed almost to a stop―a thousand years in the Astral plane felt like only a day to the traveler. Creatures did not go hungry or age while in the Astral plane. For that reason, its mortal inhabitants needed to return to the Material Plane in order to have children or to reach adulthood.

Entering the Astral plane could be accomplished in one of two ways: projecting your astral form into the plane via the astral projection spell, or by physically entering the plane. Astral projection was the safest way to travel but still involved risk because you left your physical body behind on the traveler's plane of origin. The astral body would be accompanied by the astral forms of any items and clothing that were magical or radiated a magic aura. While projecting, your astral self was connected to your physical body by a silver cord that stretched out behind you for about 10 ft (3 m), or 1 ft (30 cm) depending on the version of the spell, and then became invisible and intangible. Very few things could sever this silver cord: a powerful psychic wind, a githyanki silver sword, or the will of gods. The physical body left behind appeared alive but did not require food, water, or air and did not age. It could be moved and was vulnerable to damage and death. If the traveler's physical body was slain, death followed the projection some minutes later. If the astral self was slain, the traveler then returned to his or her physical body in a coma. Physically entering the Astral plane required a spell such as plane shift and brought the traveler wholly into the Astral with no silver cord to anchor her to her plane of origin.

Geographical Features
Upon entering the Astral plane, the traveler saw a silvery color pool nearby&mdash;a portal to the location on the Prime Material plane he or she came from. Astral projection travelers saw their silver cord leading back to this pool. Color pools appeared as two-dimensional circles about 10‒60 ft (3‒18 m) in diameter and only visible from one side unless they had some way to detect invisible objects. Pools of different colors were portals to the different Outer planes. Each Outer plane had its own unique color, but the traveler's home portal was always a metallic silver, rippling like mercury in a pan. Color pools could be used to view the destination plane before stepping through by mentally concentrating on the nearby pool until it became transparent. A viewer could also move (with some limitations) the portal's viewpoint by concentration. Astral projecting travelers formed a new physical body (with silver cord attached) when they stepped through a color pool to their destination plane. The new body was formed out of local materials so the greater the similarity between one's home plane and the destination, the more one's new body looked like the original one.

Great Wheel
According to the Great Wheel cosmology model, the Astral plane connected the Prime Material Planes to the first layers of the Outer planes.

World Tree
In the World Tree cosmology, the Astral plane was described as a shapeless cloud that surrounded all the other planes (including the Inner Planes which were not accessible via the Astral in the Great Wheel model). The World Tree cosmology model interpreted the Astral plane as tree-shaped, touching nearly all planes, and overlapping the World Tree as well. The ramification of this was that travel between planes was not easily accomplished without going through the "trunk" of the tree (the Material plane). Direct connections between separate dominions of the gods was only possible by cooperation between the deities in question.

The Astral Plane had the following traits in the World Tree cosmology model:
 * Subjective Directional Gravity: a traveler picked a "down" direction and "fell" in the direction until a new direction was chosen.
 * Timeless: the effects of time were suspended until the traveler exited the Astral Plane, whereupon the effects retroactively occurred.
 * Mildly Neutral-Aligned: no circumstance penalties.
 * Enhanced Magic: Spells and spell-like abilities required less time to be cast.

Color pools still existed in this model, but an Astral traveler had to choose the destination plane before setting out and would only encounter pools that lead to the chosen plane. To change destinations, the traveler had to reenter the Material plane and then begin the journey anew.

Toril's Material plane actually linked to several other Astral planes, each of which connected Toril to the outer-planer homes of a different set of deities. They were based on the geographical areas of control held by the different pantheons. As such, there was an Astral Plane for the Maztican and Zakharan pantheons (even though many of the Zakharan deities resided on the Material Plane). The Kara-Turan faiths were not connected to their own astral plane, as instead their deities connected to the Spirit World. Very little was known in Faerûn about these other astral planes, but it was theorized that Ao supervised them just as he adjudicated the conflicts between the pantheons.

World Axis
According to the World Axis cosmology, the Spellplague set the dominions adrift&mdash;they were no longer linked to a tree-shaped Astral plane but floated aimlessly in the Astral Sea.

The Astral Sea was described as being "above" the Prime Material plane and its two reflections, the Feywild and the Shadowfell. The Spellplague destroyed the World Tree and set the dominions of the gods adrift to wander about in the silvery void. Access to the Astral Sea was accomplished through passages found in the world or using the proper ritual. Once in the Sea, travel was initiated by thought and was very similar to flying.

In addition to the astral dominions, the Astral Sea could be used by powerful beings to create demiplanes by focusing on an idea and applying a strong will. Each demiplane had its own traits and physical laws as dictated by the one who created it, and was always smaller than an astral dominion. If abandoned, it would break apart and fade from existence just like an astral dominion.