Portrait of William Parsons, 3rd Earl of Rosse. Public Domain

Frontiers for Young Minds takes you down on a dive into the depths of the historical scientific archives and introduces you to scientists you may have not heard about, but you should! This time, we tell you the story of William Parsons, 3rd Earl of Rosse, who found the "Whirlpool" galaxy.

By Alicia Fallows

William Parsons, 3rd Earl of Rosse, was born in June 1800, and at age 41 inherited his earldom and an estate in what is now County Offaly, Ireland, from his father. In 1845, he would become known for creating the largest telescope in the world and with remarkable drawings, discovering the spiral nature of the “Whirlpool” galaxy – a breakthrough that deserves to always be remembered!

The Parsons Family

The Parsons family arrived at Birr Castle in 1620, being granted the stronghold by James 1st. After two sieges in the 17th century, the castle was restored and remodeled. Perhaps the most exciting part of the history of Birr Castle, the Parsons family’s focus on scientific development, came in the 19th century, and would ignite a legacy of scientific research in the family. One of the greatest engineering feats and discoveries at Birr was by the 3rd Earl of Rosse, William Parsons, who created the “Leviathan of Parsonstown”. After experimenting in creation of several telescopes in the pursuit of his passion for astronomy, Parsons set about developing a particularly impressive structure, culminating in an extraordinary mirror telescope that would make an astonishing discovery.

The Largest Telescope in the World

Leviathan of Parsonstown photographed in 1885. Credit: National Library of Ireland on The Commons

In the 1840s Parsons envisaged and constructed his most exciting structure yet. Parsons was fortunate enough to be able to do so thanks to his wife, Mary Parsons (a pioneer in her own right in the field of photography) and her family fortune. At their home, Birr Castle, he experimented for several years, figuring out how to successfully cast his own mirrors and make the telescope maneuverable. Supported by experts in the creation, this culminated in the development of a reflecting telescope that stood in a structure around 50ft tall and had a 72inch aperture – the largest telescope in the world, which was dubbed the “Leviathan of Parsonstown”.

The telescope held the status of largest in the world (in terms of aperture size) for an amazing 72 years, and in its heyday people flocked from across the world simply to view this marvel of engineering. If they were lucky, they would also observe the night sky.

Spiral Galaxies

Sketch by Lord Rosse of the Whirlpool Galaxy in 1845. Public Domain

The remarkable telescope in the hands of William Parsons was responsible for one of the most significant discoveries in 19th century astronomy. Through observations and detailed pencil and chalk drawings, Parsons revealed the spiral structure of what were called ‘nebulae’ at the time.

In fact, Parsons’ drawings were of spiral galaxies, a class of galaxies containing their own stars and dust with spiral arms extending from the center. Many of these drawings can be seen on display in Birr Castle today, with their detail and passion clear. One of the first of these drawings was of the now infamous Whirlpool galaxy, M51 (Messier object 51.)), a galaxy that is 31 million light-years away from Earth (equating to around 6 trillion miles!). Parsons’ comprehensive drawing, created around 1845, remarkably resembles modern day photographs - an unbelievable triumph using an incredible telescope.

Birr Castle as Location of Science - Looking Forwards

William Parsons’ extraordinary contributions to astronomy ought to never be forgotten. Thankfully, many members of the Parsons family continued in pursuit of science; astronomy was continued at the castle by one of William’s sons, and Charles Parsons invented the steam turbine.

Today, the Parsons family continues to contribute to science and education, with an active Science Centre and the installation of part of I-LOFAR (International Low Frequency Array) radio telescope in Birr Castle’s grounds. This telescope is observing the universe at a new level of detail in low radio frequencies, assisting the next forefronts of research in big bang cosmology, extragalactic surveys, space weather and more.

Perhaps there are further discoveries yet still to come from Birr!

If you’d like to know more about how a radio telescope works and what it can discover, consider reading this Frontiers for Young Minds article: What do Radio Waves Tell Us about the Universe?