Discovery of Neptune
The planet
In retrospect, after it was discovered, it turned out it had been observed many times before but not recognized, and there were others who made calculations about its location which did not lead to its observation. 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. These irregularities could, however, be resolved if the gravity of a farther, unknown planet were disturbing its path around the Sun.
In 1845, astronomers Urbain Le Verrier in
The discovery of Neptune led to the discovery of its moon, Triton, by William Lassell just seventeen days later.[4]
Earlier observations
Neptune is too dim to be visible to the naked eye: its apparent magnitude is never brighter than 7.7.[5] Therefore, the first observations of Neptune were only possible after the invention of the telescope. There is evidence that Neptune was seen and recorded by Galileo Galilei in 1613, Jérôme Lalande in 1795, and John Herschel in 1830, but none are known to have recognized it as a planet at the time.[6] These pre-discovery observations were important in accurately determining the orbit of Neptune. Neptune would appear prominently even in early telescopes so other pre-discovery observation records are likely.[7]
In 1847,
Irregularities in orbit of Uranus
In 1821,
In modern terms, the problem is an
On 13 February 1844, James Challis, director of the Cambridge Observatory, contacted Astronomer Royal George Biddell Airy at the Royal Observatory, Greenwich, and requested data on the position of Uranus for Adams.[1] Adams certainly completed some calculations on 18 September 1845.[1]
Adams supposedly communicated his work to Challis in mid-September 1845, but there is some controversy as to how. The story and date of this communication only seem to have come to light in a letter from Challis to the
Meanwhile, on 10 November 1845,
The search
Upon receiving in England the news of Le Verrier's June prediction, George Airy immediately recognized the similarity of Le Verrier's and Adams' solutions. 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.[24][25] At a July 1846 meeting of the Board of Visitors of the Greenwich Observatory, with Challis and Sir John Herschel present, Airy suggested that Challis urgently look for the planet with the Cambridge 11.25 inch equatorial telescope, "in the hope of rescuing the matter from a state which is ... almost desperate".[26] The search was begun by a laborious method on 29 July.[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. Only after the discovery of Neptune had been announced in Paris and Berlin did it become apparent that Neptune had been observed on August 8 and August 12 but because Challis lacked an up-to-date star-map, it was not recognized as a planet.[20]
Discovery observation: 24 September 1846
Le Verrier was unaware that his public confirmation of Adams' private computations had set in motion a British search for the purported planet. On 31 August, Le Verrier presented a third memoir, now giving the mass and orbit of the new body. 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.[citation needed]
Galle received Le Verrier's letter in the morning of 23 September. Galle, an assistant at the Berlin Observatory, proceeded to ask the director of the observatory, Johann Franz Encke, to use their Fraunhofer telescope (aperture of 9 inches/24.4 cm). Encke celebrated his 55th birthday that day and permitted the use of the telescope. Galle's and Encke's conversation was overheard by Heinrich Louis d'Arrest, a student that was working at the observatory, who excitedly asked Galle for the permission to join the observations. Galle allowed d'Arrest to join and even asked him conduct preparations. At first they followed Le Verrier's instructions to look for a disk on the sky, but without success. They also used the standard sky chart, but soon noticed that stars were missing from this sky chart. d'Arrest, suggested that a recently published chart of the sky, Hora XXI, could be compared with the current sky to seek the displacement characteristic of a planet, as opposed to a stationary star. This map was part of a series, which was waiting for another map, which is why it was not distributed worldwide at this time. With the star map in their hands they returned to the Fraunhofer telescope. 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. It didn't take long before d'Arrest exclaimed: "That star is not on the map!".[28]
The discovery was made thanks to the Hora XXI sky chart of the Berlin Science Academy completed by Carl Bremiker.[28] Originally Bessel proposed a plan to create star charts to aid the discovery of comets and minor-planets. In this plan catalogues from Bradley, Lalande and Piazzi would be reduced according to a uniform scheme and collated with the zone catalogues within 15 degrees of the equator. The catalogued stars were to be supplemented by un-catalogued stars which could be seen in a 'comet-seeker'. Twenty four astronomers were to take part in the work, each taking an hour of right ascension.[29] Work on the chart Hora XXI started in 1826, but was only completed in 1844 and printed in 1845.[28]
Neptune was discovered just after midnight,
Aftermath
On the announcement of the discovery, Herschel, Challis, and Richard Sheepshanks, foreign secretary of the Royal Astronomical Society, announced that Adams had already calculated the planet's characteristics and position. Airy, at length, published an account of the circumstances, and Adams's memoir was printed as an appendix to the Nautical Almanac.[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.[21]
A keen controversy arose in France and England as to the merits of the two astronomers. There was much criticism of Airy in England. Adams was a diffident young man who was naturally reluctant to publish a result that would establish or ruin his career. Airy and Challis were criticised, particularly by James Glaisher,[3] as failing to exercise their proper role as mentors of a young talent. Challis was contrite but Airy defended his own behaviour, claiming that the search for a planet was not the role of the Greenwich Observatory. On the whole, Airy has been defended by his biographers.[3] In France the claims made for an unknown Englishman were resented as detracting from the credit due to Le Verrier's achievement.[20]
The
I mention these dates merely to show that my results were arrived at independently, and previously to the publication of those of M. Le Verrier, and not with the intention of interfering with his just claims to the honours of the discovery ; for there is no doubt that his researches were first published to the world, and led to the actual discovery of the planet by Dr. Galle, so that the facts stated above cannot detract, in the slightest degree, from the credit due to M. Le Verrier.
— Adams (1846)[31]
The criticism was soon afterwards made, that both Adams and Le Verrier had been over-optimistic in the precision they claimed for their calculations, and both had, by using
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.[21] In 1874–1876, Adams was President of the Royal Astronomical Society when it fell to him to present the RAS Gold Medal of the year to Le Verrier.[20]
Later analysis
The conventional wisdom that Neptune's discovery should be "credited to both Adams and Le Verrier"[32] has recently been challenged[33] putting in doubt the accounts of Airy, Challis and Adams in 1846.[34][35][36]
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.[37] 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.[38] 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."[39]
Beyond Neptune
Even before Neptune's discovery, some speculated that one planet alone was not enough to explain the discrepancy in Uranus' orbit. On 17 November 1834, the British amateur astronomer the Reverend Thomas John Hussey reported to Airy a conversation he had had with Bouvard. Hussey reported that when he suggested to Bouvard that the unusual motion of Uranus might be due to the gravitational influence of an undiscovered planet, Bouvard replied that the idea had occurred to him, and that he had corresponded with Peter Andreas Hansen, director of the Seeberg Observatory in Gotha, about the subject. Hansen's opinion was that a single body could not adequately explain the motion of Uranus, and postulated that two planets lay beyond Uranus.[40]
In 1848, Jacques Babinet raised an objection to Le Verrier's calculations, claiming that Neptune's observed mass was smaller and its orbit larger than Le Verrier had initially predicted. 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.[40] 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."[40]
As of 2024, no large planet has been found beyond Neptune that would explain any alleged discrepancy, despite the discovery of
Neptune discovery telescope
The
See also
Further reading
- Hubbell, J. G.; Smith, R. W. (November 1992). "Neptune in America – Negotiating a Discovery". History of Astronomy Journal. 23 (4): 261. S2CID 117707321.
- Lecture notes with orbital positions at the time of discovery.
References
- ^ a b c d Kollerstrom, N. (2001). "A Neptune Discovery Chronology". The British Case for Co-prediction. University College London. Archived from the original on 2005-11-19. Retrieved 2007-08-23.
- ^ Bibcode:1946C&T....62..369D.
- ^ required.)
- .
- ^ Williams, David R. (September 1, 2004). "Neptune Fact Sheet". NASA. Retrieved 2007-08-14.
- ^ J J O'Connor; E F Robertson (September 1996). "Mathematical discovery of planets". Retrieved 2009-09-11.
- S2CID 4317020.
- Bibcode:2008DIO....15....3K. Retrieved 29 March 2016.
- ISBN 978-0-8050-7133-7.
- ISBN 978-0-486-43602-9.
- ^ Britt, Robert Roy (2009-07-09). "New Theory: Galileo Discovered Neptune". Space.com. Retrieved 2009-07-10.
- ISBN 978-0-521-78981-3. Retrieved 2009-09-11.
- U.S. Navy. Archived from the originalon 2011-06-06. Retrieved 2009-09-11.
- ^ Günther Buttmann. The shadow of the telescope: a biography of John Herschel. James Clarke & Co. p. 162.
- ^ Bouvard (1821)
- ^ [Anon.] (2001) "Bouvard, Alexis", Encyclopædia Britannica, Deluxe CDROM edition
- ISBN 978-0-19-861412-8. (Subscription or UK public library membershiprequired.)
- ^ a b c Kollerstrom, N. (2001). "Challis' Unseen Discovery". The British Case for Co-prediction. University College London. Archived from the original on 2005-02-06. Retrieved 2007-08-23.
- ^ Sampson (1904)
- ^ a b c d e f g h Chisholm, Hugh, ed. (1911). . Encyclopædia Britannica. Vol. 1 (11th ed.). Cambridge University Press. p. 178.
- ^ a b c d e Sheehan, W.; et al. (2004). "The Case of the Pilfered Planet — Did the British steal Neptune?". Scientific American. Retrieved 2008-02-08.
- ^ a b Rawlins, Dennis (1992). "The Neptune Conspiracy" (PDF).
- ^ Chambers & Mitton (2014) pp. 38-39
- ^ Dennis Rawlins, Bulletin of the American Astronomical Society, volume 16, p. 734, 1984 (first publication of British astronomer J.Hind's charge that Adams's secrecy disallows his claim).
- ^ Robert Smith, Isis, volume 80, pp. 395–422, September 1989
- ^ Smart (1947) p. 59
- ^ Adams's final prediction on 2 September 1846 was for a true longitude of about 3151⁄3 degrees. That was 12 degrees west of Neptune. The large error was first emphasized in D. Rawlins (1969). "Review of Colin Ronan Astronomers Royal". Sky and Telescope. 38: 180–182. Adams's exact calculation of his prediction of 3151⁄3 degrees was recovered in 2010.
- ^ a b c "The history behind the AIP logo | AIP". www.aip.de. Retrieved 2023-03-06.
- Bibcode:2000IAUJD...6E..20J.
- ^ "A brief History of Astronomy in Berlin and the Wilhelm Foerster Observatory". www.planetarium.berlin. Archived from the original on September 24, 2015. Retrieved September 23, 2010.
- ^ Adams, J.C. (1846). "On the Perturbations of Uranus (p. 265)". Appendices to various nautical almanacs between the years 1834 and 1854 (reprints published 1851) (note that this is a 50Mb download of the pdf scan of the nineteenth-century printed book). UK Nautical Almanac Office, 1851. Retrieved 2008-01-23.
- ^ Encyclopædia Britannica. Vol. 27 (15 ed.). 1993. p. 524.
- ^ Rawlins, Dennis (1992). "The Neptune Conspiracy: British Astronomy's PostDiscovery Discovery" (PDF). Dio. Retrieved 2008-03-10.
- .
- .
- .
- ^ Kollerstrom, Nick (2001). "Neptune's Discovery: The British Case for Co-Prediction". University College London. Archived from the original on 2005-11-16. Retrieved 2012-06-28.
- ^ Christine McGourty (2003-04-10). "Lost letters' Neptune revelations". BBC News. Retrieved 2009-09-23.
- ^ William Sheehan; Nicholas Kollerstrom; Craig B. Waff (December 2004). "The Case of the Pilfered – Did the British steal Neptune?". Scientific American. Retrieved 2011-01-20.
- ^ S2CID 144255699.
- S2CID 5135498.
- ^ "Astronomy in Berlin: Johann Friedrich Galle". bdaugherty.tripod.com. Archived from the original on July 19, 2011. Retrieved September 25, 2010.
- ^ "Frommers: Deutsches Museum". www.frommers.com. Archived from the original on August 1, 2010. Retrieved September 25, 2010.
Bibliography
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- Airy, W., ed. (1896). The Autobiography of Sir George Biddell Airy. Cambridge University Press. from Project Gutenberg
- [Anon.] (2001) "Bouvard, Alexis", Encyclopædia Britannica, Deluxe CDROM edition
- Baum, R.; Sheehan, W. (1997). In Search of Planet Vulcan: The Ghost in Newton's Clockwork Universe. Plenum. ISBN 978-0-306-45567-4.
- Bouvard, Alexis (1821). Tables astronomiques publiees par le Bureau des Longitudes de France. Paris, FR: Bachelier. Bibcode:1821tapp.book.....B.
- Chambers, John; Mitton, Jacqueline (2014). From dust to life : the origin and evolution of our solar system. Princeton, New Jersey: Princeton University Press. OCLC 859181634.
- Chapman, A. (1988). "Private research and public duty: George Biddell Airy and the search for Neptune". Journal for the History of Astronomy. 19 (2): 121–139. S2CID 126074998.
- Dieke, S. (1970). "Heinrich Louis D' Arrest". ISBN 978-0-684-10114-9.
- Doggett, L. E. (1997). "Celestial mechanics". In Lankford, J. (ed.). History of Astronomy, an Encyclopedia. pp. 131–40. ISBN 9780815303220.
- Dreyer, J. L. E. & Turner, H. H. (eds) (1987) [1923]. History of the Royal Astronomical Society [1]: 1820–1920. pp. 161–2.
{{cite book}}
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has generic name (help)CS1 maint: multiple names: authors list (link) - Grosser, M. (1962). The Discovery of Neptune. Harvard University Press. ISBN 978-0-674-21225-1.
- Grosser, M. (1970). "Adams, John Couch". ISBN 978-0-684-10114-9.
- Harrison, H. M (1994). Voyager in Time and Space: The Life of John Couch Adams, Cambridge Astronomer. Lewes: Book Guild, ISBN 0-86332-918-7
- Hughes, D. W. (1996). "J. C. Adams, Cambridge and Neptune". Notes and Records of the Royal Society. 50 (2): 245–248. S2CID 146396595.
- Hutchins, R. (2004) "Adams, John Couch (1819–1892)", Oxford Dictionary of National Biography, Oxford University Press, accessed 23 August 2007 (subscription or UK public library membershiprequired)
- J. W. L. G. [J. W. L. Glaisher] (March 1882). "James Challis". Monthly Notices of the Royal Astronomical Society. 43 (4): 160–179. .
- Kollerstrom, Nick (2001). "Neptune's Discovery. The British Case for Co-Prediction". Unuiversity College London. Archived from the original on 2005-11-11. Retrieved 2007-03-19.
- ISBN 978-0-471-96015-7.
- Nichol, J. P. (1855). The Planet Neptune: An Exposition and History. Edinburgh: James Nichol.
- O'Connor, J. J.; Robertson, E. F. (1996). "Mathematical discovery of planets". MacTutor History of Mathematics archive. University of St. Andrews. Retrieved 2007-09-17.
- Rawlins, Dennis (1992). "The Neptune Conspiracy" (PDF). DIO, the International Journal of Scientific History. 2 (3): 115–142.
- Rawlins, Dennis (1994). "Theft of the Neptune papers" (PDF). DIO, the International Journal of Scientific History. 4 (2): 92–102. Bibcode:1994DIO.....4...92R.
- Rawlins, Dennis (1999). "British Neptune Disaster File Recovered" (PDF). DIO, the International Journal of Scientific History. 9 (1): 3–25.
- Sampson, R.A. (1904). "A description of Adams's manuscripts on the perturbations of Uranus". Memoirs of the Royal Astronomical Society. 54: 143–161. Bibcode:1904MmRAS..54..143S.
- Sheehan, W.; Baum, R. (September 1996). "Neptune's Discovery 150 Years Later". Astronomy. 24 (9): 42–49. Bibcode:1996Ast....24...42S.
- Sheehan, W.; Thurber, S. (2007). "John Couch Adams's Asperger syndrome and the British non-discovery of Neptune". Notes and Records of the Royal Society. 61 (3): 285–299. S2CID 146702903.
- Sheehan, W; et al. (2004). "The Case of the Pilfered Planet — Did the British steal Neptune?". Scientific American. 291 (6): 92–99. PMID 15597985. Retrieved 2 January 2019.
- Smart, W. M. (1946). "John Couch Adams and the discovery of Neptune". S2CID 4074284.
- Smart, W. M. (1947). "John Couch Adams and the discovery of Neptune". Occasional Notes of the Royal Astronomical Society. 2: 33–88.
- Smith, R. W. (1989). "The Cambridge network in action: the discovery of Neptune". Isis. 80 (303): 395–422. S2CID 144191212.
- Standage, T. (2000). The Neptune File. Penguin Press.
- Unknown (October 11, 1980). "Did Galileo See Neptune?". Science News. 118 (15): 231. JSTOR 3965133.
External links
- "Lecture XV. The Discovery of Neptune". librivox. in "Pioneers of Science by Oliver Lodge (1887)". librivox. (audio files)