Sudekum Planetarium

This discussion is an addendum to the article "Not Much Eyesight, Plenty of Vision" in the December 2009 issue of Sky & Telescope.

Planetarium directors interviewed for this article:

Alan Friedman, Science education consultant, New York City; directed New York Hall of Science and Lawrence Hall of Science planetariums
Ron Kaitchuck, Professor of Astronomy and Planetarium Director at
Ball State University, Muncie, Indiana
Laurent Pellerin, Director of the Kika Shilva Pla Planetarium, Santa
Fe College, Gainesville, Florida
Steve Russo, Manager of the Suits-Bueche Planetarium, Schenectady, New York
Dennis Schatz, Senior Vice President of Strategic Programs, Pacific
Science Center, Seattle; directed the Center's planetarium

“Planetariums with domes 40 feet or less in diameter account for two-thirds of planetarium audiences,” says Ron Kaitchuck. “We are the small-dome majority.” These smaller planetariums are most often found in schools and universities. They have small staffs (usually one person) and they frequently try to serve all grade levels as well as the general public. Five veteran planetarium directors who have made careers of serving elementary school, high school, and college students offer their thoughts about the available technology and their educational challenges.

Education in planetariums

The function of a planetarium is to educate, says Kaitchuck. That's not what movie theaters do. If planetariums try to become movie theaters, they're doomed.

Dennis Schatz agrees. He thinks too many planetariums are trying to duplicate an Imax thrill show on their domes. They're losing connection to the night sky and the basics of astronomy.

A planetarium is for educating people about the sky, says Russo. Schools drive 300 miles to come to us, he says, because the planetariums closer to them are only showing movies. The teachers tell me, “We want to see the sky and learn astronomy.”

Yes, says Friedman, some planetariums are fascinated more with technology than the people they serve.

People are immersed as never before, adds Pellerin. Digital projectors give planetariums an immersive environment that can teach a huge variety of subjects in addition to astronomy. My planetarium can become a “molecularium” to teach the chemistry of water. With video projection, my audiences can be inside the body of a girl who has diabetes or they can watch fish on a coral reef."

Planetariums should emphasize where we are and how we fit in the universe, Kaitchuck says. We should emphasize the scale of the universe and its awesome beauty. A key part of the planetarium experience for young and old alike is contact with a live person who can answer questions and inspire. That makes it a personal experience.

Russo recently visited the Fairbanks Planetarium in St. Johnsbury, Vermont. It's the only public planetarium in the state. The instrument is a Spitz A2 that was installed in 1961. The planetarium show used no slides, no special effects. It was a one-hour sky talk. Russo says it was one of the best planetarium shows he's seen in years.

Do Planetariums Teach?

Do students really learn when they visit planetariums for school shows? That's the persistent question for planetarium educators, says Russo.

Russo doesn't know of major scientific studies that that have answered that question. Planetarium directors note that a scientific study of whether planetariums educate involves too many variables: What planetarium? What show? What educational objectives? What age students? What backgrounds? What quality of classroom teacher? And many more.

A great obstacle to a scientific study of this question is the fact that teachers and students are extremely busy. They find it unattractive to participate in a thorough probe. Moreover, if the students and teacher know ahead of time that they're going to be tested, that biases the study. If the testing is a surprise, that adds stress, and again biases the study.

But Russo and most other planetarium directors are convinced their programs are truly educational and beneficial based on less rigorous measurements:



  • Schools keep coming back each year.
  • Teachers report that they learned from the programs.
  • Teachers report that students remember the information when they get back their classrooms.
  • The students have a good time with science.
  • Even when school budgets are cut, planetarium visits continue.


“I want to hear gasps from the audience,” says Kaitchuck. “The gasps tell me they get it.”

Optical-mechanical versus digital planetariums

Optical-mechanical planetariums, made mostly by Zeiss, Spitz, Goto, Konica Minolta, and Viewlex, owned the field for 60 years. But beginning in 1983, a huge change swept over the planetarium field with the introduction of digital planetarium projectors, led by Evans & Sutherland, Spitz, Konica Minolta, Sky-Skan, and Global Immersion. The position, brightness, distance, and motion of each star were part of a computer program that used a video projector to create a simulation of the night sky.

The main job of a planetarium is to reproduce the stars as realistically as possible, says Russo. A video projector can't do that. Video stars are jumpy and not points.

Ron Kaitchuck, an astronomer with a strong appreciation for the night sky, says digital star projectors don't reproduce the stars well enough yet; they're dim and fuzzy. But digital projectors are cheaper, initially at least, so that's the direction most school planetariums go.

Dennis Schatz disagrees: I don't think a digital star field bothers the public.

No, says Russo, the public indeed notices when the stars are blurry. As a classicist, he prefers slide projectors for special effects. Take a Hubble Space Telescope image of the Orion Nebula and project it side by side on a dome using a slide projector and a video projector. The slide has vivid color and brightness and sharpness. Crystal clear. The video projection: no comparison.

Yes, says Alan Friedman, optical-mechanical star fields are better than digital star fields, but digital star fields convey an adequate illusion, and their ability to carry audiences through the star field and create other visual effects is worth the degradation in star quality.

The rise of video projection has provided planetariums with more elaborate special effects than ever before: racing through a star field at superluminal speeds, standing on Io with active volcanoes all around and Jupiter rotating in the background, flying around a spiral galaxy to see it face on and edge on as it collides with another galaxy.

Computers and digital projection have greatly speeded up and reduced the cost of planetarium program production, says Laurent Pellerin. At the same time, they have vastly increased a planetarium's ability to create moving, spinning, zooming special effects.

Because digital planetarium programs are computer files, says Pellerin, they can be reused without delay. They can be adapted readily. A piece of one show can quickly be inserted into another.

Friedman is a big fan of the digital revolution. It has freed planetariums from the design, maintenance, and clutter of special effect projectors. With digital planetariums, one institution can e-mail its programs to another.

Which is best? Funds permitting, most planetarium educators want both: an optical-mechanical planetarium paired with a digital planetarium. A hybrid system is ideal, they say. That's what Laurent Pellerin has at his planetarium: a Goto Chronos and a Spitz SciDome. That's what Ron Kaitchuck is installing: a Goto Chronos and an Evans & Sutherland Digistar 3. And, with an integration unique in the United States, that's what Kris McCall and her colleagues have built at the Sudekum Planetarium in Nashville.


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