From the very beginning, Armagh Planetarium was envisioned as a place for the public to experience the wonders of the Universe in the dome theatre equipped with the latest technology. The first projector was GOTO Mars, which could project up to 4,500 fixed stars from its lens projection system mounted on two starballs, and included individual lamps to project images of the Sun, the Moon, and the planets. The latest projection system is fully digitised, using two Sony GTZ270 laser diode projectors and the Digistar 7 planetarium technology. Armagh Planetarium was at the forefront of the shift towards video projection systems.
Creating the illusion of Space
When it opened, the Planetarium’s Star Theatre was dominated by the black spidery projector which was encircled by reclined seating for 100 people. The projector was ‘Mars’ (or Model M-1), the first Japan-made planetarium lens projector. Sir Patrick Moore – at that point already an established presenter of ‘Sky at Night’ – was tasked with equipping the dome as the first director of the Planetarium, and travelled to Japan to procure the Mars projector.
Soon special effects projectors were added to the Star Theatre, to enhance shows with images of rotating planets and moving spacecraft, and even panoramas of alien landscapes. Each effect needed its own dedicated projector, so over 50 individual slide projectors were housed on a specially built circular shelf around the dome. This system was very complex but worked brilliantly.
Image: Armagh Planetarium’s first projector: GOTO Mars from Japan (around 1970)
Armagh starts the video revolution
Under the directorship of Terence Murtagh, the team at Armagh was constantly introducing new technologies to enhance the audience’s experience. Terence Murtagh recognised the possibility of exploiting the new technology of video projectors to provide the show’s special effects, eliminating entirely the need for dozens of slide projectors.
Video tape recorders were very new and rare at this time and this research was very ambitious. Many technical hurdles stood in the way. Off-the-shelf video projectors were designed to present the image on a flat screen rather than a curved dome, so the Planetarium staff had to modify their projectors – otherwise the planets would look egg-shaped! At first the images appeared in grey boxes on the dome, totally spoiling the illusion. This problem was resolved by adding new electronic circuit boards to exaggerate the image’s colour and brightness lowering the contrast until the objects appeared naturally surrounded by the inky blackness of space.
This revolutionary development was a great success and Armagh Planetarium was the first planetarium in the world to project video on its dome. Other planetaria around the world followed our lead. The pioneering efforts at Armagh laid the foundations for the full-dome projection technology that was to become Digistar.
Image: Our historic first video projection system mounted under the Viewlex-Minolta dumbbell projector in 1978
Another world first
Yet another world first in the Star Theatre was the introduction of an electronic audience participation system. Now the audience could control the show themselves! Each seat was fitted with a small keypad, using this device the audience could use their buttons to respond to multiple choice quizzes in the show, be polled on their preferences and even steer the direction of the show by selecting the topics. Space Odyssey, created in Armagh, was the world’s first ever completely interactive planetarium show. Again this innovation from Armagh has spread to planetaria world-wide.
Image: World’s first interactive planetarium system, with keypads on the seats for the audience to direct the show (1980s)
Further Improvements
Planetariums have come a long way since they first appeared in the 1920s. The dream equipment then was the electromechanical star projectors brought to their developmental zenith by the famous Zeiss optical company in Germany. Today Zeiss still makes some of the best optical star projectors systems in the world with wonderfully sharp stars.
In the 1980s, the Star Theatre was continually being enhanced with the latest technology, three more video projectors were added, so effects could be displayed in all four directions, even directly overhead. Computer controlled laserdisc players replaced the videotape players from the 1970s.
Armagh Planetarium’s hemispherical domed ceiling was divided into sectors where videos were shown, slides were projected either as individual images or collectively as precisely registered all-skies: and on top of this the stars were added in by the starball projector. All of these systems, including the theatre sound tracks, were computer controlled: they required a lot of time-consuming maintenance to keep running in good operational order. The 35 mm slide projectors were very noisy and all of the incandescent bulbs leaked light and generated lots of heat.
Image: Director Terence Murtagh pictured at the Star Theatre console (around 1980)
Dawn of the Digistar era
Armagh went partly digital when we sold our Minolta-Viewlex star projector and bought our first Evans & Sutherland Digistar system in 1994. This was a revolutionary new approach to planetarium display equipment and the start of our journey into this exciting new way to present information to our visitors. Breaking with the fifty-year-old traditional ‘star ball’ design, the new digital projector formed each star on a high voltage cathode ray tube individually under computer control. A custom ‘fish-eye’ lens projected the stars on the dome. The stars and other images were greenish, rather like the early computer screens when word processors became popular. This was the first Digistar projector to be installed in the UK. Once again Armagh Planetarium was leading the way.
Determined to keep abreast of the latest technology, the Planetarium upgraded the Digistar to a more powerful Digistar II as soon as it became available in 1995, and then the first fully-digital system, Digistar 3, in 2006. We continue to keep up with the latest technological advancements to this day.
Image: The Digistar 2 projector sat in the centre of the Theatre and used a fisheye lens to project the starfield (between 1995 and 2006)
Armagh Planetarium projection systems through the years
- Mars (Model M-1) projector by GOTO – centrally mounted ‘starball’ lens projection system (1968-1977)
- Viewlex-Minolta Roman IIb projector – centrally mounted ‘starball’ lens projection system (1977-1994)
- Digistar 1 projector by Evans & Sutherland – single centrally mounted digital projector (1994-1995)
- Digistar II by Evans & Sutherland – single centrally mounted digital projector (1995-2006)
- Digistar 3 by Evans & Sutherland – six Barco SP 909 CRT projectors arranged around the edge of the dome; first true full-dome video system (2006-2011)
- Digistar 4 by Evans & Sutherland – two digital projectors (2011-2014)
- Digistar 5 by Evans & Sutherland – two digital projectors(2014-2020)
- Digistar 6 by Evans & Sutherland – two digital projectors (2020)
- Digistar 7 by Evans & Sutherland – two digital projectors (2021-); Sony GTZ270 laser diode projectors providing 4K native resolution and a contrast ratio of up to 20,000:1 on the dome. Images are processed using three computers, a host and a graphic processor for each projector, to produce dynamic, real-time representations of the cosmos onto the dome. A 64bit LED cove lighting system illuminates the dome when entering and leaving. A 5.1 audio system from Dante provides a high quality audio experience to accompany the digital presentations.
