The Astral Border, also known as the Astral Sea, was thought by some to be boundless. According to the Cosmic Wheel model, the Astral plane was the space between the Material Realm and the Upper Realms and Lower Realms. It was a barren absence, composed of other-dimensional nothingness extending in all directions, and what little solid substance that floated in the bright, silvery void was typically chunks of matter broken off from their original plane. The Astral had no gravity, but objects did retain their mass, so forceful movements could still propel creatures 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 other planes in order to have children or to reach adulthood.