(Not really blue, but I wanted to illustrate the fact that it’s a higher frequency than the Etheric-double).
The Astral-body is approximately the shape of the human body, and is connected to the other body-systems via a thin, flexible-lengthed energy-line to the belly area.
When the meat-body is asleep (or “daydreaming”), the astral-body will move away from it (usually upwards), and drift around during dreaming but a sudden unexpected sound can often cause it to snap back into the meat-body position, which can be experienced as a slight shock. This phenomena of Astral-body leaving and snapping-back also often happens during meditation.
When in good condition the astral-body is very playful and curious. This can be seen in the behavior of dolphins and whales who have a lot of awareness in their Astral-body.
Most ghosts are Astral-body’s which have persisted after the death of the meat-body (which can be used as something for the Real-i (if there is one present) to hold on to), often due to trauma which the being is unwilling to face yet.