Celebrating 100 years of Planetaria

What is a planetarium?

The initial meaning of the word planetarium could be applied to any model or representation of the Solar System, usually one with moving parts. These days we tend to think of a planetarium as a circular theatre space that allows audiences to experience celestial objects and other phenomena.  

Planetaria (the plural of planetarium) have a domed ceiling which images are projected on to, creating an immersive environment. In the UK and Ireland there are over 50 planetaria, some of them are fixed and some are portable. 

Planetaria before 1923

The first official planetarium projection occurred in the Deusches Museum in Munich on the 21st October 1923. However, the idea of using a dome to show the night sky was not a new one in 1923. Many palaces and religious buildings have included domes with night skies, planets and constellations depicted in them throughout history.  

In the 1200s Arab craftsmen made a tent that had holes in it that could be revolved allowing observers to witness the changing nature of the night sky during the day. 

In the 1654 the Globe of Gottorf was constructed. This globe was 3m in diameter. The exterior showed the globe as it was known at the time. The inside had paintings of the sky and constellations. It had a bench inside that up to 12 visitors could sit on.  

If you search for the “oldest planetarium in the world” using an internet search engine, the most common answer is the Eise Eisinga planetarium in Franeker in the Netherlands, which has been operational since 1781. It is a very accurate mechanical orrery which depicts the locations of celestial objects. The orrery took 7 years to build. Mercury, Venus, Earth, Mars, Jupiter and Saturn are all depicted in this orrery. Uranus is not shown in the orrery because it was discovered the year the orrery was completed. There was no room to add Uranus, or later Neptune because the orrery was located on the ceiling of the living room of the scientist Eise Eisinga who had built it.  

Planetarium projectors

The projector used in the Deutsches museum was a type of projector sometimes referred to as a star ball.  The star ball itself looks a bit like it has been taken straight out of a sci fi film. The initial projection system could only show the northern hemisphere sky, but shortly afterwards an adaptation was made to make the star ball look a bit like a dumbbell allowing the skies of both hemispheres to be observed. Later on these star balls were used alongside slide projectors to show the night sky. Over 60 astronauts between 1960 and 1975 used adapted versions of these starball projectors to train for space missions. This was so the astronauts would be able to reliably find guide stars to aid them in their flight.  Some planetaria still use a modern version of these starballs, but there are now many other ways to project inside a planetarium.  

From 1963 images could fill the dome without the use of a starball, by using a fisheye lens. This allowed for planetaria to be opened up to study more than astronomy, as other natural phenomena such as clouds could be shown on these lenses.  

In 1983 Digistar became the first digital planetarium projection system. It was produced by Evans and Sutherland. This meant that not only could you look up at space, but you could actually fly though it.  

These days there are many different ways that planetaria may project images onto their dome. We use 13 projectors precisely aligned together to bring our shows to life.   

The oldest planetarium in the UK

The first planetarium in the UK was the London Planetarium which opened in 1958. It seated about 330 people under an 18m dome. It is no longer operational as a planetarium instead it now houses a 4D cinema experience as part of Madame Tussauds.     

Armagh planetarium is now the oldest working planetarium in the British Isles.  

Armagh opened its doors to the public in 1968. Sir Patrick Moore, the namesake of the National Space Centre’s planetarium, was the first planetarium director at Armagh.  

As well as being the longest running planetarium in the British Isles, it also is a place where several worldwide planetarium firsts occurred. These included the first projection of videos onto the dome and the first planetarium with an inbuilt audience response system.