Illustration of the French astronomer and mathematician Urbain Jean Joseph Le Verrier (1811-1877). Le Verrier predicted the existence of the planet Neptune when he deduced that irregularities in the orbit of Uranus were due to the gravitational effect of an unknown planet. He calculated the mass and orbit of the supposed planet, and, in 1846, sent a prediction of its position to Johann Galle in Berlin, who found it almost immediately. From 'Popular Astronomy' by Camille Flammarion (1880).