John Couch Adams | Biography

John Couch Adams was born near Launceston, England, the son of a poor tenant farmer in 1819. Adams was a shy, precocious child whose early knowledge of astronomy was self-taught. In his teens he had constructed his own sundial and spent time studying solar altitudes. In 1839 he entered Cambridge University on a scholarship. Adams was a diligent student, working as a tutor during the academic year and sending his earnings home to his family. Adams had an extraordinary interest in his astronomical studies, and in 1841 he began devoting all his free time to a focused study of the orbit of Uranus.

Since Sir William Herschel's discovery of Uranus in 1781, astronomers had been puzzled by its irregular orbit and began to consider the possible existence of another planet's gravitational force as the cause of Uranus's orbital fluctuations. By 1843 Adams's diligence paid off as he graduated first in his class in mathematics and completed his calculations on the location of the unknown planet.

Adams assumed that the unidentified planet orbited in the same plane and was approximately the same size as Uranus. He also estimated its distance from the sun to be about 39 Astronomical Units (39 times the distance of the Earth to the sun). In 1845 Adams presented a paper on his calculation of the location of the new planet to George Airy, England's Astronomer Royal. Unfortunately, Airy was uninterested and chose not to pursue Adams's findings. And though Adams was a brilliant and earnest scholar, he did not aggressively push for an investigation of his findings. Commentators have suggested that Airy may have been working on his own theory which proposed that Uranus's erratic orbit implied a fault in Isaac Newton's law of gravity. Whatever the cause for his inaction, Airy's disregard for Adams's findings caused quite a controversy.

In June of 1846, almost a year after Adams's submission, French mathematician and astronomer Jean Urbain Le Verrier announced that he had determined the position of a new planet. Motivated perhaps by nationalist pride, Airy asked the director of the Cambridge Observatory, James Challis, to use Adams's figures to locate the planet. However, Johann Gaulle of the Berlin Observatory beat the English to the discovery, using Leverrier's calculations to find the planet on September 23, 1846. The following day in Paris, Leverrier was credited with the discovery of the planet he named Neptune.

Leverrier was praised around the world for the discovery, but within a year John Herschel and James Challis publicized the fact that Adams's calculations were completed earlier than Leverrier's. A vigorous debate about who should get credit for discovering Neptune began ringing across the English Channel. Adams was eventually acknowledged as the true discoverer of the planet, but through no effort of his own. His kind and unassuming nature prevented him from taking part in the sniping, and it was with genuine pleasure and admiration that he met Leverrier at Oxford in 1847.

In 1851 Adams became president of the Royal Astronomical Society, and in 1858 he began his tenure as the Lowndean professor of astronomy at Cambridge University. He succeeded James Challis as director of the Cambridge Observatory in 1860. In keeping with his tendency to avoid the spotlights of both controversy and commendation, he declined the prestigious position of Royal Astronomer, from which Airy had recently retired, and refused a knighthood. Adams spent much of his later years studying the orbital motion of the Leonid meteor swarm. He died in Cambridge in 1892.