After U. Herschel discovered Uranus in 1781 and calculated the parameters of its orbit, rather soon mysterious anomalies in the movement of this planet, it was "behind" the calculated, then ahead of it. The orbit of Uranus did not correspond to Newton's law. It also has led to an idea of the existence of one more planet behind Uranus which could distort a trajectory of movement of the 7th planet by the gravitational attraction.
In 1832, in a report by the British Association for the Development of Science, J. Erie, who later became a royal astronomer, noted that over the past 11 years the error in the position of Uranus had reached almost half a minute of arcs. Shortly after the report was published, Erie received a letter from the British amateur astronomer, the Reverend Dr. Hassay, suggesting that these anomalies were due to the effects of the still undiscovered "Zauranic" planet. Apparently, it was the first proposal to look for a "disturbing" planet. Erie did not approve of Hassay's idea, and the search was not started.
A year earlier, a talented young student, J.K. Adams, noted in his notes: "At the beginning of this week, the idea arose to study the anomalies in the movement of Uranus, which are still unexplained. It is necessary to find out whether they can be conditioned by the influence of the undiscovered planet behind it and, if possible, to determine at least approximately the elements of its orbit, which can lead to its discovery.
Adams was not able to begin this task until two years later, and by October 1843 the preliminary calculations had been completed. Adams decided to show them to Erie but failed to meet the royal astronomer. All Adams had to do was return to Cambridge, leaving Erie with the results of his calculations. For unknown reasons, Erie reacted negatively to the work of Adams, at the cost of which was the loss of English priority in the discovery of the new planet. Regardless of Adams, he worked on the problem of the Zuranic planet in France by W. J. Leverrier. November 10, 2010.
He presented his theoretical analysis of the movement of uranium to the French Academy of Sciences in 1845, concluding that there were discrepancies between the observations and calculations: "This can be explained by the influence of an external factor, which I will assess in the second treatise. Such assessments were made in the first half of 1846. The success of the case was helped by the proposal that the planet in question was moving, according to the empirical Titius Bode rule, in an orbit with a radius equal to that of Uranus, and that the orbit had a very small inclination to the plane of the ecliptic. Liveries gave instructions on where to look for a new planet.
Having received the second track of Leverieu, Eri drew attention to the very close coincidence of the results of Adams' and Leverieu's researches related to the movement of the alleged planet, disturbing the movement of Uranus, and even stressed this at a special meeting of the Council of Greenwich inspectors. But he, as before, did not hurry to start searching and began to bother about them only in July 1846, realizing what indignation can cause his passivity later on.
Meanwhile, Leverieu finished another study on August 31, 1846, in which the final system of elements of the orbit of the desired planet and its place in the sky was obtained. But in France, as in England, astronomers all did not offend to the search, and September 18, Leverieu addressed to I. Galle, assistant to the Berlin Observatory, September 23, together with a student Darré began the search. Their calculations were based on the results of observations of Jupiter, Saturn, and Uranus itself. On the first evening, the planet was discovered, just 52 from its intended location. The news of the discovery of the planet "at the tip of the pen", which was one of the brightest triumphs of heavenly mechanics, soon flew the entire scientific world. By established tradition, the planet was named Neptune in honor of the ancient god.
For about a year there was a struggle between France and England for the priority of discovery, which, as it often happens, the heroes themselves were not directly related. In particular, Adams and Leverieu established a full understanding, and they remained friends for the rest of their lives.
Neptune has 8 known satellites: 4 small, 3 medium and 1 big.