Frederick William Herschel (1738-1822), German- British astronomer. Herschel discovered the planet Uranus in 1781, which resulted in his appointment as private astronomer to England's King George III. He constructed a telescope with which he discovered two of the moons of Uranus (Titania and Oberon) and two of Saturn (Mimas and Enceladus). In 1783 he documented the intrinsic motion of the Sun through space. He also determined that the Milky Way is a galaxy, by counting the number of stars found in different directions. He found that most stars in the Milky Way lie in the galactic plane, and the least at the celestial poles.