When it comes to exploring space from here on the ground, there’s a small number of companies that design and build planetariums, where the expanses of space come to life overhead. This team allows students, hobbyists and scientists to experience the complexity of space for themselves.

As the galaxy is changing, the technology used to present it to us—in domed, specialized viewing areas—has also been evolving.

Behind the curtain is a team of experts with backgrounds in science, astronomy and entertainment—some who have used telescopes and others who have provided light shows for big-name pop stars or IMAX movies. The challenge is to continue bringing the immensity of space indoors, with changing technologies and public sensibilities.

Most planetariums use a combination of mechanical and analog star ball projectors and digital projectors to show images and videos probing further into space. 

Contractors and integrators that find themselves renovating or constructing planetariums will be meeting specific condition requirements for this environment, including running speaker wire and installing fixed and ball-style LED light projectors. These spaces require a massive amount of connectivity so the data collected through a variety of projects—with telescopes all over the world—can be shared between other planetariums. In some cases, the systems need to be digitally accessed by devices on-site, such as oculars (AR glasses) or headsets.

Retired architect Tim Barry, a member of the International Planetarium Society (IPS), has practiced architecture on more than 100 million cubic meters of projects. In retirement, he has been advising planetariums on design and construction for the IPS. He’s seen the variety of challenges and options available to schools and museums, based on physical space and budget.

“It’s a really exciting, interesting field, but it’s a very small market,” Barry said. 

Before the COVID-19 pandemic, there were approximately 4,500 planetariums worldwide, with 1,750 in North America. Post-pandemic, many planetariums closed globally. Industry members estimate there are now 1,400 in North America, but this number is growing.

Star projectors dating back a century

The earliest planetariums were simply dark rooms with a domed ceiling, painted with stars. In early 20th century Germany, scientists began exploring lighting the ceiling up.

The Deutsche Museum in Munich was the site for the first projected planetarium, with a star-ball consisting of light emitted from the center of the ball through many lenses to represent the night sky, designed and built by Zeiss. It provided a view only of the sky above Europe at the time.

Such planetariums soon opened around the world, covering the expanse of views globally. In 1930, the Adler Planetarium in Chicago was the very first one to open in the Western Hemisphere. 

The original star-ball projector continues to operate in a similar way to its predecessor, although it now uses LED lamps. (Laser lamps are another option.)

In the 1990s, the digital age brought us images and information from beyond our view from earth. The result was complete hemispherical, large-scale domes with direct illumination. These sites use projectors located around the room to display an image or video on the ceiling. Some planetariums continue to leverage their star balls but have added digital features, with two disparate systems that can be tied together with software.

Other systems are provided as a single solution, using the best of both technologies, said Ken Yager, planetarium sales agent for Seiler Instrument Inc., St. Louis. He pointed out that Zeiss offers a full solution with a hybrid approach, which Seiler sells to some customers.

From small school or mobile units to megadomes

Connecting the projectors, as well as audio and life safety systems, requires considerable coordination, Barry said, while also communicating to servers so content can be shared with other such sites.

Today, dome-casting software can display the planetarium’s own presentation, or access an event that’s being simulcast in a dozen or more sites around the world. The presentation relies on the visual and sound effects, which may be due for some updates. 

“We’ve been so focused on the visual side, we really are lagging on the audio side,” Barry said. 

The most common sound system for such facilities is Dolby 5.1—or its equivalent—with six speakers, along with a 2K projector system, he said. It has significant upgrade potential, and that means new audio distribution systems may be installed within, above and below some domes. For instance, some new planetariums with 20 or more speakers could be ahead, with related cables and connections. 

Barry expects that audio engineers will begin to take the technology and expertise gained from live-music theaters, opera houses and symphony halls and create better quality sound to complement the high-quality visuals. In the future, visitors could connect their hearing aids to the local system, for instance, just as those with visual impairment might be able to access the imagery with AR glasses.

Other interactive components could include multiple choice questions flashed up on the screen, with audience members picking an answer using a device built into their seat’s armrest. 

“The electrical connection is the key to this, so [electricians are] going to be right in the middle of an exciting time of new technologies,” Barry said.

Providing fire safety where absolute dark is needed 

As in any public space, safe exits are essential, but planetariums offer a special challenge. A constantly illuminated exit sign, while offering safe egress in the dark, can easily disrupt the entire experience.

Human eyes require about 15 minutes to fully adjust to absolute dark, and the exit signs are especially distracting during that time. Some sites choose to disconnect their exit signs; however, they still need to operate when an emergency occurs. 

The solution in some cases requires working with local fire marshals and fire codes to coordinate an automated shutoff switch that turns off the exit lights as the program begins, and, if an emergency occurs, the fire detection system automatically turns exit signs and all the lights back on.

Floor exit lighting is another low-voltage installation that must be coordinated with the system designers. There are other emergency offerings, however, said Barry. 

“We’ll have strobes and horns and other enunciation equipment, so now, if you can add a little more intelligence to the system, you can have the exit signs go dark until there is an issue,” he said.

A handful of global companies

Selling planetarium systems in the United States, Seiler Instrument offers equipment from Zeiss, which also offers the Uniview centralized software solution for digital and analog projector systems. 

Uniview was created by the American Museum of Natural History (AMNH) in New York, and Lindskoping University in Stockholm, based on the NASA Digital Universe Atlas data set. Zeiss was one of the original distributors of Uniview before buying the software platform and modifying it to be more specifically useful for planetariums. Another software option, OpenSpace, is created by many of the same individuals related to AMNH and Lindskoping. 

Zeiss makes a Skymaster ZKP 4 LED projector for small and midsized domes. In 2008 Zeiss created the Velvet LED digital projector for black night and bright stars. Zeiss also offers its first new star-ball system in 20 years, the Asterion, which is designed to be part of a hybrid system with the Velvet projectors to cover the transition from “feet on the ground” to traveling virtually throughout the known universe, Yager said.

Coordinating multiple projectors across a single screen is another challenge. Multiple projected images on a screen can lead to what experts call edge blending at the point where separate images meet. That can be solved on the projector level and with the software.

The science of creating the proper image requires engineering.

“You get into this challenge of accommodating the resolution, which is easy to do, but then you have to tweak the contrast ratio to get the projectors to blend together,” he said, adding that, ultimately, there needs to be a seamless, complete hemispheric image. 

The future will bring more AR-type features, which could include using AR glasses, for instance, Barry said. 

However, according to Yager, most public schools and colleges and universities still teach classic feet-on-the-ground astronomy, rather than using interactive experiences with AR glasses.

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