Blog 6 – IAU100 and Ireland’s Involvement

Last week, we set up an exhibition here in Birr for the International Astronomical Union’s (IAU) 100th Anniversary. The exhibition is called Above and Beyond: Making Sense of the Universe for 100 Years. It details the major discoveries and events which have shaped astronomy since the IAU was established in 1919. It was launched here in Birr, in John’s Hall, on the evening of Thursday 8th August with some lovely words from Professor Tom Ray of DIAS. It will remain here and in the I-LOFAR Education Centre until Friday 16th August, before travelling onto Dublin with DIAS. 

Professor Tom Ray and Lord Rosse at the IAU100 Exhibition in John’s Hall, Birr

Professor Tom Ray speaking at the IAU100 Exhibition Launch in John’s Hall, Birr

Setting it up was a difficult process at first as there was only myself, Áine and Jeremy to do so, and some of the pieces are very large and awkward. We struggled through the first day alone, but luckily we got some help the next day with a visit from Eileen Flood from DIAS! Eileen and her husband kindly helped us get the last of the exhibition assembled and ready to go. As we set it up, it was a great opportunity to learn about how astronomy developed over the past century and really get a feel for Ireland’s role in this journey. 

Since the start of the 20th Century, and indeed even long before that, Ireland has played an active role in discovering more about our Universe. In 1917, the Hooker Telescope in Mount Wilson Observatory, California, USA was constructed. This overtook the Leviathan Telescope here in Birr as the largest optical telescope in the world, with a mirror 2.5m in diameter and allowed for cutting edge astronomy that could view the Universe as it had never been seen before. Previous to this, in the 1840s and 1850s, the Third Earl of Rosse was the first person in the world to view what were known as “spiral nebulae”. Astronomers at the time didn’t know what these nebulae were. Some believed they were small and on the outskirts of our galaxy, the Milky Way, while others thought they were separate galaxies, large and very far away. This new idea, that there were galaxies other than our own, sparked a debate that raged on for decades and anyone who wanted to see these spiral nebulae for themselves, had to come to Birr to do so. Eventually, with the completion of the Hooker Telescope, Edwin Hubble was able to prove that many of these nebulae were much further away than the reach of the Milky Way. This was evidence that they were indeed other galaxies, and the question that started with the Third Earl of Rosse in Birr was settled. 

The 3rd Earl of Rosse’s drawing of the Whirlpool Galaxy

On the 29th May 1919, a total solar eclipse occurred that was used to test Einstein’s Theory of General Relativity. The theory predicted that the light coming from stars around the Sun would be deflected due to the mass of the Sun. Two expeditions set out to test this, one led by Eddington and Dyson to an island off the coast of Africa, and another by Irish astronomer Andrew Crommelin to a town called Sobral in Brazil. Not only was one of these expeditions led by Crommelin from Co. Antrim, but the equipment used was Irish made. The Grubb Coelostat reflected light from the sky onto a fixed telescope and the Einstein Lens was used to focus the light onto a photographic plate. These pieces of equipment were both made by Howard Grubb, who was one of the most famous telescope makers in the world, from Rathmines in Dublin. The researchers confirmed that the light was deflected by the amount predicted by Einstein’s theory and Ireland was key to proving Einstein’s Theory of General Relativity.

The Grubb Coelostat

In July 1967, Jocelyn Bell Burnell, who was then a PhD student at the University of Cambridge, detected some irregularities in her data while studying quasars. She had inadvertently discovered pulsars, which are rapidly rotating neutron stars that release jets of radiation from their poles. Professor Bell Burnell is from Lurgan in Co. Armagh and her major discovery has led to many developments in our understanding of the universe. Observations of a pulsar in a binary star system were used to confirm the existence of gravitational waves, the first exoplanet was discovered around a pulsar, and some pulsars are better than atomic clocks at keeping time!


Currently, I-LOFAR is located here in Birr and it is part of a european wide network of radio telescope arrays called LOFAR. LOFAR is the largest low frequency radio telescope in the world and once again Ireland is part of cutting edge research – keeping up a long tradition! 


Blog post written by Jane Dooley.