How do Planetariums Work?

The definition of a planetarium facility built primarily for presenting programming on astronomy, the night sky, and for training in celestial navigation. Most planetariums are recognized by the large dome-shaped projection screen onto which scenes of stars, planets and other celestial objects can be made to appear and move to simulate the complex motions of celestial objects. Visuals are created using a wide variety of technologies such as optical-mechanical star projectors slide projector, video and full-dome projector systems, and lasers. Planetarium projection systems can be set to display the sky at any point in time, and often to show the night sky as it would appear from any point of latitude on Earth.

Traditional Planetariums

Planetarium programming was originally based on the use of optical-mechanical devices called star-balls, which project points of light onto a dome. These star projectors are simple and effective analogs to the night sky, and included a geared system to reproduce the motion of the planets. Planetarium operators and producers often combined 35mm still projectors, standard video, and a variety of specially built mechanical projectors to display visual effects and images to build programming for the dome. These systems are still used today in planetariums across the global and are referred to as traditional planetariums and make up roughly 65% of the domes in the world.

Digital Full Dome Planetariums

In the late 1980s, computers and digital projectors were introduced to the dome environment. This technology was often used integrated into traditional planetariums. It wasn’t until the late 1990’s that digital full dome animated content was able to be displayed allowing producers to create visual tours of the universe and other realistic environments in the dome expanding program beyond just the night sky and astronomy. Over the past twenty years, these digital full dome systems have improved with faster computer processors and graphic cards to now allow the ability to use 4K (5.5x more resolution over high definition) and 8K projectors to display imagery and programming, including 3D, only hinted at by the early video systems. Digital full dome systems are now able to replace out traditional systems allowing for a single dome solution and are replacing traditional domes at an increasing rate.

‘Imiloa’s Planetarium is a Digital Full Dome System and was the first in the world to have 3D stereoscopic projection capabilities.