Discovery of Neptune
By 1846, the planet Uranus had completed nearly one full orbit since its discovery by William Herschel in 1781, and astronomers had detected a series of irregularities in its path that could not be entirely explained by Newton's law of universal gravitation.
In 1845, astronomers Urbain Le Verrier in Paris and John Couch Adams in Cambridge separately began calculations to determine the nature and position of such a planet.
[10] However, in July 2009, University of Melbourne physicist David Jamieson announced new evidence suggesting that Galileo was indeed aware that he had discovered something unusual about this "star".
Although his telescope was powerful enough to resolve Neptune into a small blue disk and show it to be a planet, he did not recognize it at the time and mistook it for a star.
In 1821, Alexis Bouvard had published astronomical tables of the orbit of Uranus, making predictions of future positions based on Newton's laws of motion and gravitation.
Adams believed that he could use the observed data on Uranus and Newton's law of gravitation to deduce the mass, position, and orbit of the perturbing body.
[citation needed] After his final examinations in 1843, Adams was elected fellow of his college[17] and spent the summer vacation in Cornwall beginning his calculations.
"[21] Meanwhile, on 10 November 1845, Urbain Le Verrier presented to the Académie des sciences in Paris a memoir on Uranus and showed that the pre-existing theory failed to account for its motion.
[20] Unaware of Adams's work, he attempted a similar investigation, and on 1 June 1846, in a second memoir presented to a public meeting of the Académie, he gave the position, but not the mass or orbit, of the proposed perturbing body.
Up until that moment, Adams' work had been little more than a curiosity, but independent confirmation from Le Verrier spurred Airy to organize a secret attempt to find the planet.
[3] Adams continued to work on the problem, providing the British team with six solutions in 1845 and 1846 [22][27] which sent Challis searching the wrong part of the sky.
[20] Le Verrier was unaware that his public confirmation of Adams' private computations had set in motion a British search for the purported planet.
Having been unsuccessful in his efforts to interest any French astronomer in the problem, Le Verrier finally sent his results by post to Johann Gottfried Galle at the Berlin Observatory.
Galle was at the telescope reading the star positions while d'Arrest was sitting at a nearby table and checking the coordinates against the Hora XXI chart.
After two further nights of observations in which its position and movement were verified, Galle replied to Le Verrier with astonishment: "the planet whose place you have [computed] really exists" (emphasis in original).
[20] However, it appears that the version published by Airy had been edited by the omission of a "crucial phase" to disguise the fact that Adams had quoted only mean longitude and not the orbital elements.
[citation needed] The new planet, at first called "Le Verrier" by François Arago, received by consensus the neutral name of Neptune.
Its mathematical prediction was a great intellectual feat, but it showed also that Newton's law of gravitation, which Airy had almost called in question, prevailed even at the limits of the Solar System.
[20] Adams held no bitterness towards Challis or Airy[3] and acknowledged his own failure to convince the astronomical world:[21] I could not expect however that practical astronomers, who were already fully occupied with important labours, would feel as much confidence in the results of my investigations, as I myself did.By contrast, Le Verrier was arrogant and assertive, enabling the British scientific establishment to close ranks behind Adams while the French, in general, found little sympathy with Le Verrier.
[34][35] In 1999, Adams's correspondence with Airy, which had been lost by the Royal Greenwich Observatory, was rediscovered in Chile among the possessions of astronomer Olin J. Eggen after his death.
[36] In an interview in 2003, historian Nicholas Kollerstrom concluded that Adams's claim to Neptune was far weaker than had been suggested, as he had vacillated repeatedly over the planet's exact location, with estimates ranging across 20 degrees of arc.
Airy's role as the hidebound superior willfully ignoring the upstart young intellect was, according to Kollerstrom, largely constructed after the planet was found, in order to boost Adams's, and therefore Britain's, credit for the discovery.
[37] A later Scientific American article by Sheehan, Kollerstrom and Waff claimed more boldly "The Brits Stole Neptune" and concluded "The achievement was Le Verrier's alone.
He postulated, based largely on simple subtraction from Le Verrier's calculations, that another planet of roughly 12 Earth masses, which he named "Hyperion", must exist beyond Neptune.
[39] Le Verrier denounced Babinet's hypothesis, saying, "[There is] absolutely nothing by which one could determine the position of another planet, barring hypotheses in which imagination played too large a part.
