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The Pre-Discovery Observations of Uranus

1982; Cambridge University Press; Volume: 60; Linguagem: Inglês

10.1017/s025292110008235x

2059-9137

Eric G. Forbes,

History and Developments in Astronomy

In his Astronomisches Jahrbuch for 1784, Johann Elert Bode summarises the scanty information that had reached Berlin concerning the recent discovery on 13 March 1781 of a new heavenly body by a still-unidentified observer in England. Its easterly progress through the Milky Way during the interim six months had been parallel to the ecliptic, and thus entirely consistent with the view - hitherto based only upon its brightness and clearly-defined disc - that it was a planet and not a comet. Bode therefore asks why this sixth-magnitude object had not been previously detected, and raises the question of whether it had in fact been observed by earlier astronomers but misidentified as a star. He himself had already scanned the star-catalogues of Tycho Brahe, Johann Hevelius, John Flamsteed, and Tobias Mayer; and had come to suspect that a missing sixth magnitude star in the constellation Capricorn, observed by Tycho on 20 November 1589, might have been the planet. A second possibility which still required investigation was Mayer’s star No. 964, observed in Aquarius on 25 September 1756.