Neptune

Most remote of the planets. Distance from the sun 2,792,000,000 m.; diameter 34,800 m.; ma 17.1 that of the earth; density 1.11 that of water; time of revolution about the sun 164.78 years. It was discovered by Galle at Berlin Sept. 23, 1846, within 52' of the place predicted by Leverrier from the perturbations produced in Uranus. (See also ADAMS, JOHN C.) It was found that the planet had been observed six times before this date, the observers supposing it a fixed star. There is one satellite, distant from the planet 225,000 m.; period 5d. 21h. 2m. 44.2s. The motion is retrograde; inclination of satellite's orbit to plane of ecliptic 34° 48'.