William Parsons, 3rd Earl of Rosse
|The Earl of Rosse|
William Parsons, 3rd Earl of Rosse
17 June 1800|
|Died||31 October 1867
William Parsons, 3rd Earl of Rosse, KP (17 June 1800 – 31 October 1867) was an Anglo-Irish astronomer who had several telescopes built. His 72-inch telescope "Leviathan", built 1845, was the world's largest telescope until the early 20th century.
He was born in Yorkshire, England, in the city of York, the son of an Irish peer. He was educated at Trinity College, Dublin, and Oxford University's Magdalen College, graduating with first-class honors in mathematics in 1822. He inherited an earldom and a large estate in King's County (now County Offaly) in Ireland when his father Lawrence Parsons, 2nd Earl of Rosse died in 1841.
- Lawrence Parsons, 4th Earl of Rosse (17 November 1840 – 30 August 1908).
- Reverend Randal Parsons (26 April 1848 – 15 November 1936).
- Hon. Richard Clere Parsons (21 February 1851 – 26 January 1923), apparently known for developing railways in South America.
- Sir Charles Algernon Parsons (13 June 1854 – 11 February 1931), known for inventing the steam turbine.
In addition to his astronomical interests, Rosse served as a Member of Parliament (MP) for King's County from 1821 to 1834, an Irish representative peer after 1845, president of the Royal Society (1848–1854), and chancellor of Trinity College, Dublin (1862–1867).
Scientific studies 
During the 1840s, he had the Leviathan of Parsonstown built, a 72-inch (6 feet/1.83 m) telescope at Birr Castle, Parsonstown, County Offaly. The 72-inch (1.8 m) telescope replaced a 36-inch (910 mm) telescope that he had built previously. He had to invent many of the techniques he used for constructing the Leviathan, both because its size was without precedent and because earlier telescope builders had guarded their secrets or had simply failed to publish their methods. Rosse's telescope was considered a marvelous technical and architectural achievement, and images of it were circulated widely within the British commonwealth. Building of the Leviathan began in 1845 and it was first used in 1847. It was the world's largest telescope until the early 20th century. Using this telescope Rosse saw and cataloged a large number of galaxies.
Lord Rosse performed astronomical studies and discovered the spiral nature of some nebulas, today known to be spiral galaxies. Rosse's telescope Leviathan was the first to reveal the spiral structure of M51, a galaxy nicknamed later as the "Whirlpool Galaxy", and his drawings of it closely resemble modern photographs.
Rosse named the Crab Nebula, based on an earlier drawing made with his older 36-inch (91 cm) telescope in which it resembled a crab. A few years later, when the 72-inch (183 cm) telescope was in service, he produced an improved drawing of considerably different appearance, but the original name continued to be used.
A main component of Rosse's nebular research was attempting to resolve the nebular hypothesis, which posited that planets and stars were formed by gravity acting on gaseous nebulae. Rosse himself did not believe that nebulas were truly gaseous, but rather that they were made of such an amount of fine stars that most telescopes could not resolve them individually (that is, he considered nebulas to be stellar in nature). Rosse and his technicians claimed to resolve the Orion nebula into its individual stars, which would have cosmological and even philosophical implications, as at the time there was considerable debate over whether or not the universe was "evolved" (in a pre-Darwinian sense), a concept with which Rosse disagreed strongly. Rosse's primary opponent in this was John Herschel, who used his own instruments to claim that the Orion nebula was a "true" nebula, and discounted Rosse's instruments as flawed (a criticism Rosse returned about Herschel's own). Eventually, neither man (nor telescope) could establish sufficiently scientific results to resolve the question (the convincing evidence for the gaseous nature of the nebula would be developed later from spectroscopic evidence, though it would not resolve the philosophical issues).
One of Rosse's telescope admirers was Thomas Langlois Lefroy, a fellow Irish MP, who said, "The planet Jupiter, which through an ordinary glass is no larger than a good star, is seen twice as large as the moon appears to the naked eye... But the genius displayed in all the contrivances for wielding this mighty monster even surpasses the design and execution of it. The telescope weighs sixteen tons, and yet Lord Rosse raised it single-handed off its resting place, and two men with ease raised it to any height."
Lord Rosse's son published his father's findings, including the discovery of 226 NGC objects in the publication Observations of Nebulae and Clusters of Stars Made With the Six-foot and Three-foot Reflectors at Birr Castle From the Year 1848 up to the Year 1878, Scientific Transactions of the Royal Dublin Society Vol. II, 1878.
Lord Rosse's telescopes 
- 15-inch (38 cm)
- 24-inch (61 cm)
- 36-inch (91 cm) (aka Rosse 3-foot telescope)
- 72-inch (180 cm) (aka Rosse 6-foot telescope or Leviathan), started in 1842 and completed in 1845.
- "Telescopes: Lord Rosse’s Reflectors". Amazing-space.stsci.edu. Retrieved 2012-09-03.
- The York Courant, Monday 23rd June 1800; Archives and Local History, York Explore Centre, Museum Street, York YO1 7DS
- Hughes, Stefan (2012). Catchers of the Light: The Astrophotographers' Family History. Google Books. p. 1085. ISBN 978-1620509616. http://books.google.co.uk/books?id=iZk5OOf7fVYC&pg=PA1085.
- Lefroy, T. 1871, Memoir of Chief Justice Lefroy, Hodges, Foster & Co., Dublin.
- "Photos". Klima-luft.de. Retrieved 2012-09-03.
- Hansard 1803–2005: contributions in Parliament by the Earl of Rosse
- A list of galaxies credited to Parsons for seeing first
- William Parsons' biography written in 1868 as an obituary, published in Monthly Notices of the Royal Astronomical Society
- Website of Birr Castle, where the telescope was located, has some historical info
- Lundy, Darryl, p. 1279 #i12787, The Peerage
|Parliament of the United Kingdom|
John Clere Parsons
|Member of Parliament for King's County
with Thomas Bernard 1821–1833
Nicholas Fitzsimon 1833–1835
1821 – 1835
John Craven Westenra
The Earl of Limerick
|Representative peer for Ireland
The Lord Dunboyne
|New title||Lord Lieutenant of King's County
|Peerage of Ireland|
|Earl of Rosse