Leviathan of Parsonstown

The Leviathan of Parsonstown is a Newton telescope within the grounds of Birr Castle in County Offaly, Ireland. The massive tube is suspended between two tall stone walls, while the speculum mirror itself was cast from copper and tin.

William Parsons built this instrument between 1842 and 1845 to study nebulae and distant galaxies. It remained the largest telescope in the world for over 70 years and allowed astronomers to see spiral structures in space for the first time.

The telescope enabled astronomers to identify spiral structures in galaxies, including the detailed observation of the Whirlpool Galaxy M51.

The telescope stands on the grounds of Birr Castle, where visitors can view the structure and surrounding walls. On clear days, the system of cables, weights, and pulleys that once controlled its movement can be seen.

The metal mirror required regular polishing because it tarnished quickly through oxidation and lost its reflective power. Astronomers climbed platforms to reach the eyepiece, which moved to different positions depending on where the instrument was pointed.

Location: County Offaly

Inception: 1845

Creator: William Parsons, 3rd Earl of Rosse

Website: https://birrcastle.com/telescope-astronomy

GPS coordinates: 53.09677,-7.91758

Latest update: December 5, 2025 22:29