Technical Considerations
Fiber
Almost all designs use plastic (PMMA) fiber in several diameters.
.75mm fiber is the base size for the star field effect. Using various diameters, as well as varying the fiber-end distance from the ceiling improves realism. The recommended sizes are 5mm, .75mm, 1.5mm, and 3mm.
Typically unjacketed fiber is used. If the ceiling is translucent (perforated, for example) it would be wise to use jacketed fiber to prevent the ceiling from glowing.
Sometimes, acrylic shapes are side lit to create certain shapes (the rings of Saturn, for example)
Light Source
In these systems, the light source of choice is the low wattage quartz halogen LS. Semi-custom kits use Quartz Halogen or HID. LED light sources are also available.
Heat and lamp maintenance are the major "design challenges" to overcome when using Quartz Halogen or HID lighting. Typically, the light source is installed in the ceiling, requiring additional electrical outlets or wiring the LS directly into an existing light circuit. As a matter of convenience, the LS should be located in a closet (for lamp changing) , but this limits the pattern coverage when using a system - unless an extension bundle is used.
Design
In real life, the distribution of stars in any given field of view is random. However, we tend to be uneasy with large voids and have an urge to balance the star effect, which reduces realism.
Site location is an important consideration. In the city, far fewer stars are seen than if the observer is in the suburbs or a rural area. For general consideration, a star density 1.5 - 3 stars per sq ft is used. This number can also vary with the type of light source used, the ambient lighting, the distance of the star field from the viewer, and the desired effect, i.e. to create the illusion of a galaxy, densities 2-3x the above are required.
Motion can be created by a special placement of the fibers in the common end (known as mapping), combined with the use of electronic control. DMX (Digital multiplexing) control is a serial communication technique used to remotely manage light output (dimming, on/off) of several light sources. In addition, color/twinkle wheels are also controlled; their speed, direction, and start/stop times are controlled thru a "DMX" controller. Shooting stars and spinning nebulae effects can be achieved. Most home Star Scenes do not use DMX.