Irish Astronomy's "Golden Age" and the world's largest telescope

Ireland was home to the world’s largest telescope during its “Golden Age” and County Armagh remains home to the oldest planetarium in the British Isles. Michael O’Shea explores astronomy's incredible history with the Armagh Observatory and Planetarium.

Matthew McMahon is the Museum Collections Officer at the Armagh Observatory and Planetarium in Northern Ireland. I spoke to Matthew to find out how and why Ireland, despite its famously rainy weather, had the world's most powerful telescopes for almost a century during its “Golden Age", and why Armagh, famous for its cathedrals, has been a center for astronomy research and education from the late 18th century onward.

I also learned how the interests and influence of the Anglo-Irish came to bear on astronomy during time, and how the Famine did — and didn’t — impact — the construction of mammoth telescopes.  

What’s special about the Armagh Planetarium?

The Planetarium in Armagh is the oldest, continuously operational planetarium in the British Isles. It's been operational since it opened in 1968.

The founder of the planetarium, Dr. Lindsay, was very struck by the fact that if he wanted to get people interested in astronomy first, he would need a planetarium, given that the reliability of actually getting a view of the stars through a telescope in Northern Ireland is limited.

What was the Golden Age of Astronomy in Ireland?

Armagh Planetarium joined the much older Armagh Observatory, established in 1790 by Archbishop Richard Robinson at the start of the “Golden Age of Astronomy in Ireland” that lasted until the late 1800s. During this Ireland became the center of astronomical research and telescope-making, and punched well above its weight if you consider the size of the astronomical community in Ireland, and, going toe-to-toe with the various royal observatories, such as Greenwich Observatory.

The Armagh Observatory was established in 1790 by Archbishop Richard Robinson, Lord Archbishop of Armagh.

Isn’t it too cloudy or rainy to do astronomy in Ireland?

That's very much where the observatory building during this period of the 1800s comes into the story. Because if you are living in the same building where you're working, you can take advantage of the momentary openings in the sky. It's not uncommon to have nights where you get four stars, and four stars is pretty pathetic. And four stars is probably the equivalent of maybe 20-30 minutes of clear viewing. On the other hand, you have other nights where you get 80-90 minutes.

And that's what's interesting about Irish astronomy it's not necessarily sporadic, but it's very seasonal. So they're taking advantage of the long clear nights in winter, they're taking advantage of May, a very popular month, in terms of observation. And you do have better weather, you have lower winds, which is very important.

Were telescopes being manufactured in Ireland?

Oh, yes. Ireland through the Grubb Company became the center of telescope manufacturing of large telescopes globally. Thomas Grubb was an engineer who worked for the Bank of Ireland — and ostensibly a billiard table maker! But he was also interested in astronomy and a fantastic engineer and optician, able to solve engineering problems quickly and efficiently. And he started to build telescopes in the 1830s. And the first one he makes is this mammoth telescope, the largest refractor telescope in the world when it was built in 1834.

Can you talk about the international trade in telescopes that Ireland was part of? 

Grubb and other telescope makers were part of an international telescope manufacturing trade. For example, Grubb built a mammoth telescope at Markree in County Sligo in the 1830s, the largest refractor in the world at the time. And that one telescope has this fascinating history where the lens is built in Paris and half the glass of the lens is from Switzerland.

Thomas Grubb (1800-1878) created highly sought-after telescopes and helped establish Ireland a center for astronomy during the 19th century.

That’s incredible. I’ve heard Ireland was home to the world’s largest telescope in the 1800s.

Yes, the third Earl of Ross, who is a wealthy landowner down in County Offaly, had the Leviathan built in 1845 at Birr Castle, and the Leviathan is a six-foot reflecting telescope — that means the mirror inside the telescope is six foot high. And it's a fantastic instrument.

And that's really for the Golden Age kicks into overdrive because we've had good astronomers. And they've now got their hands on world-class leading instruments. For the next 72 years, the largest telescope in the world would now be based in Ireland. 

Wasn’t this also the time of the Famine?

Yes, the Leviathan telescope was first used in 1845, which leads us to the Famine. And that leads us to the difficulties of Irish astronomy. Irish astronomers were frequently Church of Ireland men, they all went to Trinity and they were Anglo-Irish. And I think that's important because that's not to say that there weren't Catholics doing astronomy. But astronomy is definitely fashionable for the Protestant Ascendancy in Ireland in the 1800s.

And so does the Famine impact Irish astronomy? Because all of these people are Protestant Ascendancy, the answer to this question is a resounding, it really doesn't, because none of them are the people that are actually going to suffer from it.

However, it is interesting to note that because the Earl of Ross, who built the Leviathan at the start of the Famine, doesn't touch it for three years because he's performing famine relief for his own estates, his own workers. So instead of getting them to make him a telescope for three years, when food is failing, he's getting them to help. He's basically telling them, we're not going to focus on engineering, we're going to focus on getting enough food.

What other stories about Irish astronomy haven’t been told? 

At the moment, we are telling the story of the Golden Age of Irish Astronomy. This is a story of the Protestant Ascendancy. However, there is another story. And it's the one that hasn't been told yet, which is everybody else that was doing astronomy. In addition to all three big observatories (Birr Castle, Dunsink Observatory, and Armagh) there are dozens of smaller observatories. And to be honest, we know very little about these. For example, there was an observatory 10 miles away from the Armagh observatory that we'd never heard of, that we'd never come across.

Looking to the future, what are you most excited about at the Planetarium?

The entire Planetarium exhibition area was redeveloped in 2021 and this summer we will have a new temporary exhibition curated by undergraduate students from the History Department of Queen's University Belfast. 

I also just accepted the donation of three archival boxes of notebooks from a farmer 20 miles west of Armagh along the border with the Republic of Ireland. He had been keeping a daily weather record for 70 years of not just rainfall and temperature and pressure, but also when certain crops are harvested this guy's writing down when he's seen certain animals. This is the climate information that our data is missing.

Say a visitor from America would like to visit the Armagh observatory. What’s the best way to get there? 

If I fly into either Belfast or Dublin, there are buses. And the best is obviously the airport bus, which is the X series. Armagh has an easy day trip, in my opinion.

There's so much to do in the city, so much history and heritage. If people are flying into Dublin as well, I'd also recommend Dunsink, which is open on Thursday nights for open nights. And it's a great look. 

It's another cracking observatory.

* For more information on the Armagh Observatory and Planetarium visit www.armagh.space.