ABSTRACT
The most important advance in nineteenth-century astronomy was the discovery of a new element in the solar system. Since 1781, when Laplace had hypothesized that this new element was a planet called Uranus, astronomers had observed deviations by the planet from its predicted orbit. In the early decades of the next century, a number of scientists suspected that these deviations might be due to another, hitherto undiscovered, planet. In 1845, a student at Cambridge, John Adams, calculated the orbit of this hypothetical planet and reported his findings to the Greenwich Observatory, which was nevertheless unable to detect it by telescope. In the meantime, the director of the Astronomical Observatory of Paris, Urban Jean Le Verrier, had independently reached the same conclusions and in 1846 announced the discovery of a new planet, to which the name of Neptune was given. The discovery was hailed as a triumph by the French scientific community, which used it as a watchword in its struggle against the Church for the monopoly of knowledge about nature. Then, however, the American astronomer Walker calculated a new orbit for Neptune which was entirely different from the one worked out by Adams and Le Verrier. Was this the orbit of the same planet or of a different one? For the American astronomers it was a different one; for the French astronomers, who had made massive investments in terms of their public image and scientific authority in Le Verrier’s discovery, it could only be Neptune, and the different orbits could only be due to errors of calculation (Shapin, 1982).
