With time, discrepancies began to appear between the predicted and observed orbits, and in 1841, John Couch Adams first proposed that the differences might be due to the gravitational tug of an unseen planet.
Co tempo comezaron a aparecer discrepancias entre as órbitas preditas e as observadas, e en 1841 John Couch Adams propuxo por primeira vez que as diferenzas poderían deberse ao tirón gravitacional dun planeta invisible.