The Leviathan of Parsonstown

31 Oct 2016

Halloween night being all about monsters, I spent it out in the dark thinking of a telescope big enough to be named after a monster – the Leviathan of Parsonstown – built in 1845 by Irish nobleman William Parsons, the third Earl of Rosse, who died 149 years ago, on this day.

With a 72-inch metal mirror weighing 3 tons and a tube 58 feet long, Lord Rosse’s Leviathan was the largest telescope in the world, a title it proudly held for over 70 years until the construction of the 100-inch Hooker telescope at the Mount Wilson Observatory, California, in 1917.

*William Parsons 3rd Earl of Rosse (1800-1867)*

The telescope’s mount was the first and last of its kind: the 58-foot telescope tube was suspended between two stone walls, 70 feet long and 50 feet high, aligned in a north-south direction, and with gothic arches in one side. An enormous system of chains, pulleys and counterweights kept the telescope in balance.

The mighty telescope opened a new window to the universe when, in April 1845, Rosse observed the ‘nebula’ M51 in Canes Venatici, and for the first time what had only been seen as a misty cloud was revealed to have spiral structure, and that it was “studded with stars”.

Workers with one of Parsons’s 72″ speculum mirrors

Until then, a nebula was a mysterious and hotly debated splotch in the heavens. The telescopes of the day were simply not powerful enough to resolve the mysterious glows of light. Now, the Leviathan of Parsonstown had revealed a hitherto hotly debated splotch as a vast and beautiful collection of stars in an object with spiral structure… the first among many ‘spiral nebulae’ that Rosse was to observe and sketch. (It was only 80 years later, in 1924, that Edwin Hubble’s observations proved conclusively that these nebulae were in fact, entire galaxies outside our own Milky Way Galaxy and millions of light-years away.)

After Lord Rosse died on 31 October, 1867 his son, the 4th Earl (Laurence Parsons) continued to operate the Leviathan, but after Laurence died in 1908, the Leviathan fell into disrepair.

The magnificent Leviathan’s surviving mirror at the Science Museum in London,

As an unbelievable indictment of war, when the First World War broke out in 1914, nearly all of the iron castings and any other metal of this magnificent telescope were melted down for scrap to build armaments. While the fate of one of the two original mirrors remains a mystery, the second is on display in London’s Science Museum today.

So, as a tribute to this tremendous astronomer and his magnificent 72 inch reflector, the Leviathan of Parsonstown, here are a few more of his stupendous sketches alongside Hubble’s images of the object.

M51

M99

M101

NGC 2903

NGC 6946

The Crab Nebula

No homage to Lord Rosse and his Leviathan would be complete without the object he so famously sketched and nicknamed the Crab Nebula in 1848.