| Soon after William Herschel discovered Uranus, the seventh planet from the sun, on March 13, 1781, some astronomers studying the new discovery observed that whenever Uranus came to a certain point in its path around the sun, it behaved in a peculiar way. Instead of continuing evenly in its orbit it turned aside in a manner that baffled the astronomers. At last it struck them that there must be some other body near enough to Uranus to act upon it, and pull it out of its course. By certain calculations they fixed upon the exact spot in the sky where the suspected body ought to be. On turning their powerful telescopes to that spot they saw for the first time the planet Neptune. |