Neptune Look up Neptune at
late 14c., "god of the sea," from Latin Neptunus, son of Saturn, brother of Jupiter, the Roman god of the sea (later identified with Greek Poseidon), probably from PIE root *nebh- "cloud" (source of Latin nebula "fog, mist, cloud;" see nebula), via a sense of "moist, wet." The planet so named was discovered by Galle in 1846. Until the identification of Pluto in 1930, it was the most distant planet known.