The Astral Space or the Astral Plane is a mana plane of existence that mirrors the physical world. All physical objects create shadowy representations of themselves in astral space. Living things have brighter forms on the astral plane, which is called an aura. The awaken have auras that are brighter and more colorful than their mundane counterparts. Nothing has a "physical" presence in astral space unless it has an astral form, though even then, nothing is truly physical on the astral.
Seeing the Unseen
To see Astral Space usually requires that a person must be awakened. Adepts and mystic adepts need the adept power of astral perception, while full mages (including hermetic mages and shamans) can naturally see in to the astral at will. Using astral perception will make the awakened person become dual natured, which means that, like awakened critters such as ghouls, hellhounds, dragons, etc., they now exist on both the physical plane and have an astral form, so exist and can interact with both the physical world and astral space. Another possibility for awakened character to see the Astral Plane is to use the awakened drug called deepweed.
The next step up from astral perception is known as astral projection. In this process, a mage can separate their astral form from their physical form. This is only freely accessible to full mages, such as hermetic mages and shamans. It frees the magician from their physical limitations and projects their very psyche into the astral. This allows them to move at the speed of thought. It is possible for non-magicians and the mundane to astrally project if near an astral rift or with aid from a powerful free spirit with the astral gateway power, though this can be very dangerous for mundanes.
Seeing, but not Seeing
The astral plane is described using sight but it is not truly sight. It is more of a third eye or empathic link. You do not see light, but emotions. You can not read the words in a book, but you can pick one up if it is beloved by its owner. Likewise, mirrors and glass on the astral plane are opaque and non-reflective, since those are concepts associated with visible light. Strangely, water is still transparent.
A blind magician (whether naturally blind or just in a dark room) switches their vision to the astral plane, while a non-blind magician views the blind mage through a one-way window. The non-blind magician can target the blind mage through the glass, while the blind magician would be unable to see the mage on the other side of the glass. Since the glass blocks the blind mage's line of sight, the blind mage is unable to target the non-blinded mage.
Lastly, non-living objects do make opaque shadows on the astral which can block line of sight, which can be handy for beings that cannot leave the astral, such as ghouls. This is also why you'll often find ghouls in tight and enclosed environments, so they don't have to worry about a projecting mage shooting them with spells that the ghoul can do nothing to stop. Some visual modifies do leave astral shadows that can affect astral sight, such as smoke grenades, fog, or rain, which can interfere with spell casting on the astral.
What Happens on the Astral Stays on the Astral
Spells on the astral plane can only be mana spells and cannot interact with the physical plane unless targeting something with an astral form. Targeting a mundane's aura is not enough to establish the link to cast a spell, for example. Likewise, a spell cast on the physical plane cannot affect the astral plane, though the spell will leave disturbances in the ambient mana, which will leave a magician's astral signature in astral space.
- Shadowrun Fourth Edition
- Street Magic
- Shadowrun Fifth Edition Core Rulebook
- Street Grimoire
- Street Magic pp.14