Computers use a code of numbers or digits to process information. Thus a planetarium with computerized projectors is known as a digital planetarium. The mechanical projectors are able to show the stars as seen from only one region of spaceour solar system. This is because the holes in their star plates cannot change position relative to one another. However, a digital projector system does not have this limitation, as it does not use star plates. Instead, a computer creates images on video screens. A lens then projects each image onto the dome. To show the stars as seen from a place other than the solar system, the computer merely changes the images on the screens.
In the early 1980s, the Evans and Sutherland Corporation of the United States set up the first digital planetarium in the Science Museum in Richmond, Virginia. Since then digital planetariums have developed further and can now produce far more realistic images of planets. These advanced planetariums can show images of the objects that are significant in fields other than astronomy. For instance, they can simulate a flight through an extremely enlarged image of a living cell. Astronomy-based computer programs, which can simulate sky conditions at any time of the day, can also be considered as digital planetariums.
Digital planetariums also present shows for entertainment. For instance, they can be used for a display of animated, computer-generated art, accompanied by a musical sound track.