A constellation projector is often referred to as a planetarium projector because it is responsible for casting images of the universe, including constellations, onto the domes in planetariums. Constellation projector plans have come a long way over the years as can be demonstrated by looking at their interesting history.

Earliest Constellation Projectors
Carl Zeiss was the first person to build a constellation projector in the year 1924. The earliest models were popular in Germany and contained only the solar system basics such as the Sun, the moon, the planets, the stars, and a few famous constellations.

Soon after the initial constellation projector was developed larger models were made that projected a greater number of stars, comets and nebulae. These more advanced projectors had realistic details, such as twinkling and twilight. They also introduced lasers to draw the lines connecting the stars in the constellations to make it easier for audience members to locate them.

Typical 1960’s Constellation Projectors
Hidden constellations continued to progress into the middle of the century. In the 1960’s most of these projectors followed a typical format. Most of these projectors were about 13 feet long and were cylindrical in shape with a sphere on both ends.

The spheres were usually about 30 inches wide and were meant to represent the northern and southern hemispheres. They typically projected 4,500 stars per hemisphere, through holes in foil that were draped over the spheres. Each of the spheres had a 1500 watt bulb in the center, meaning these were not cheap constellation projectors.

Some of the larger and brighter constellations had there own individual projectors and were not cast using the pin holes. These constellations were often tinted with color to make the more visible in the virtual night sky.

The cylindrical middle section was more than just a frame to hold the spheres; it too has individual projectors attached. These projectors were typically responsible for casting the images of the Sun, and planets.

Modern Constellation Projectors
While most planetariums still utilize the standard projector that was made popular in the 1960’s, advancements in technology have enhanced these projectors. For example, many planetariums utilize wrap around films using widescreen on their dome ceilings. In addition, laser shows and music have been added to make the viewings more entertaining. Also, many planetariums have begun using HD constellation projectors to enhance the detail of the celestial images. Some planetariums are using used constellation projectors to portray what the sky would look like from other planets besides Earth.