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'''James Challis''' [[Fellow of the Royal Society|FRS]] ([[Braintree]], [[12 de dezembro]] de [[1803]] — [[Cambridge]], [[3 de dezembro]] de [[1882]]) foi um [[Física|físico]], [[Astronomia|astrônomo]] e [[Clero|clérigo]] [[Inglaterra|inglês]].
Foi [[Professor Plumiano de Astronomia e Filosofia Experimental]] (1836–1883) e diretor do [[Observatório de Cambridge]]. É conhecido por ter perdido a oportunidade de descobrir o planeta [[Neptuno (planeta)|Netuno]] em 1846.
==Vida==
Challis nasceu em [[Braintree]], onde seu pai John Challis era [[pedreiro]]. Após frequentar algumas escolas locais, graduou-se no [[Trinity College (Cambridge)]] em 1825 como [[Senior Wrangler (University of Cambridge)|Senior Wrangler]]. Foi eleito [[fellow]] de Trinity em 1826 e ordenado em 1830. Casou com Sarah Copsey (nascida Chandler) em 1831, viúva, tendo consequentemente de renunciar a continuar fellow de Trinity. Tiveram um filho e uma filha.<ref name="ODNB">Clerke (2006)</ref>
{{em tradução|:en:James Challis}}
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==Plumian professor==
In 1836, he became director of the [[Cambridge Observatory]] and [[Plumian Professor of Astronomy and Experimental Philosophy]], holding the latter post until his death. He lectured in all areas of [[physics]]. As examiner for the Smith's prize, he appraised the early work of [[G. G. Stokes]], [[Arthur Cayley]], [[John Couch Adams]], [[William Thomson, 1st Baron Kelvin|William Thomson]] (later Lord Kelvin), [[Peter Guthrie Tait]] and [[James Clerk Maxwell]]. He was referee for Thomson and for Stokes in their respective applications for chairs at the [[University of Glasgow]], and for Maxwell at [[University of Aberdeen|Aberdeen]]. He and Thomson together set and examined the [[Adams prize]] topic on [[Saturn's rings]], won by Maxwell in 1857.
==Cambridge Observatory==
Challis succeeded [[George Biddell Airy]] at the observatory and gradually improved the instrumentation and [[accuracy and precision|accuracy]] of observations. He made some early observations of the fracture of [[comet]] [[3D/Biela]] into two pieces on 15 January 1846 and reobserved both fragments in 1852. He published over 60 [[scientific paper]]s recording other observations of comets and [[asteroid]]s. He invented the [[meteoroscope]] (1848) and the [[transit-reducer]] (1849). Challis published twelve volumes of ''Astronomical Observations Made at the Observatory of Cambridge''.<ref name="ODNB"/>
He and his wife lived at the observatory as genial hosts for 25 years, though Challis once left his wife to guard an intruder while he summoned assistance. Challis eventually resigned the observatory post because of [[chronic stress]] in his inability to keep up with processing new astronomical observations. His predecessor Airy had taken a more relaxed attitude. He was succeeded by Adams though he maintained his professorship until his death.<ref name="ODNB"/>
==The search for the eighth planet==
{{main|Discovery of Neptune}}
In 1846, Airy finally persuaded a reluctant Challis to join in the search for an eighth [[planet]] in the [[solar system]]. Adams had predicted the location of such a [[planet]] as early as 1844, based on irregularities in the orbit of [[Uranus]]. Adams failed to promote his prediction successfully and there was little enthusiasm for a systematic search of the heavens until Airy's intervention. Challis finally began his, somewhat reluctant, search in July 1846, unaware that Frenchman [[Urbain Le Verrier]] had independently made an identical prediction. German [[astronomer]] [[Johann Gottfried Galle]], assisted by [[Heinrich Louis d'Arrest]], finally confirmed Le Verrier's prediction on 23 September. The [[planet]] was named "Neptune". It soon became apparent from Challis's notebooks that he had observed Neptune twice, a month earlier, failing to make the identification through lack of diligence.<ref name="ODNB"/>
Challis was full of remorse but blamed his neglect on the pressing business of catching up on the backlog of astronomical observations from the observatory. As he reflected in a letter to Airy of 12 October 1846:<ref>Eggen (1970-1981) ''p.''187</ref>
{{ quotation | I have been greatly mortified to find that my observations would have shewn me the planet in the early part of August if I had only discussed them. ... I delayed doing this ... chiefly because I was making a grand effort to reduce the vast numbers of comet observations which I have accumulated and this occupied the whole of my time. }}
==Physicist==
Challis worked in [[hydrodynamics]] and [[optics]]. Challis supported the [[Light#Wave theory|wave theory of light]] and advanced the theory of a [[luminiferous ether]] as a medium for its propagation. However, he rejected the idea that the ether was an [[Elasticity (physics)|elastic solid]], insisting that it was a [[fluid]], bringing him into conflict with Airy and Stokes. Driven by Sir [[Isaac Newton]]'s somewhat obscure assertion of "a certain most subtle spirit which pervades and lies hid in all gross bodies",<ref>''[[Philosophiae Naturalis Principia Mathematica]]'', 2.547</ref> Challis was driven to attempt to derive all physical phenomena from a model of intert [[sphere|spherical]] [[atom]]s embedded in an [[Elasticity (physics)|elastic]] fluid ether,<ref>Challis (1869)</ref> an enterprise described as an attempt at a "[[Victorian era|Victorian]] [[unified field theory]]".<ref name="ODNB"/> His work included a [[Mechanical explanations of gravitation|mechanical explanation of gravitation]].<ref>Taylor, W. B. (1876), "Kinetic Theories of Gravitation", ''Smithsonian Report'', 205-282</ref> His ideas won few supporters.<ref name="ODNB"/>
==Theological views==
Challis took issue with [[Charles Wycliffe Goodwin]]'s views on [[Book of Genesis|Genesis]] expressed in ''[[Essays and Reviews]]'' (1860). Challis saw Genesis as an "antecedent plan" for creation, rather than a literal chronology, and argued that the [[Bible|biblical]] account could be reconciled with the [[Geologic time scale|geological record]].<ref>Challis (1861)</ref> He went on to interpret the word "law", as used in a [[spirituality|spiritual]] sense by [[Paul the Apostle|Saint Paul]], in the sense of [[scientific law]].<ref name="ODNB"/><ref>Challis (1871)</ref>
==Assessment==
Challis published 225 papers in mathematics, physics and astronomy.<ref name="eb">[Anon.] (2001)</ref> He was re-elected fellow of Trinity in 1870. He died in [[Cambridge]] and was buried beside his wife in [[Mill Road Cemetery, Cambridge|Mill Road cemetery]]. His wealth at death was £781.<ref name="ODNB"/>
Despite the embarrassment over Neptune, Challis did make genuine contributions to astronomy. His blend of theology and science was in the spirit of Stokes, and his search for a unified theory akin to the endeavours of Thomson and Maxwell. However, despite his tenacity in advocating his physical and theological theories, they had little impact.<ref name="ODNB"/> [[Olin J. Eggen]] claimed that "At a later time, or under less amiable circumstances, he would have been branded a charlatan. He would now be as forgotten as his peculiar ideas had not the events surrounding the discovery of Neptune in 1845 given him a genuine opportunity for scientific immortality. But he fumbled it."<ref>Eggen (1970-1981) ''p.''186</ref>
==Honours and memorials==
*Fellow of the [[Royal Astronomical Society]], (1836);<ref name="ODNB"/>
*[[Fellow of the Royal Society]], (1848);<ref name="ODNB"/>
*Bronze medal at the [[The Great Exhibition]] for his transit-reducer, (1851).<ref name="ODNB"/>
*The [[distributed.net]] UK team, originally [[University of Cambridge|Cambridge University]] and [[CIX]] based, is named "Prof. James Challis' Most Excellent UK Team" in his honour [http://www.winwaed.com/comp/challis/climateprediction.shtml].
*[[Lunar crater]] [[Challis (crater)|Challis]] is named after him.<ref>{{cite book | author=Cocks, E. E. & Cocks, J. C. | year=1995 | title=Who's Who on the Moon: A Biographical Dictionary of Lunar Nomenclature | publisher=Tudor Publishers | isbn=0-936389-27-3 }}</ref>
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