Neptun.

Internationalism, based on Latin Neptūnus (“Neptune, the Roman god of water and the sea”). The Norwegian form reflects the widespread international form of the name without the Latin ending -us. The deeper origin of the Latin name is disputed. One proposal derives Neptūnus from Proto-Italic *neptūnos, ultimately connecting it with Proto-Indo-European *nébʰos (“cloud, moisture, mist”) and a notion of wetness or moisture. Other etymologies have also been proposed, including comparison with the Indo-Iranian divine name Apām Napāt, but no deeper derivation is universally accepted. Compare 𐌍𐌄𐌈𐌖𐌍𐌔 (neθuns, “Nethuns”), the name of the corresponding Etruscan water deity; the exact historical relationship between the Latin and Etruscan names is uncertain. The astronomical sense is transferred from the name of the Roman deity. The planet was discovered in 1846 after Urbain Le Verrier calculated the position of a previously unknown planet from irregularities in the orbit of Uranus, allowing Johann Gottfried Galle and Heinrich Louis d'Arrest to identify it telescopically. Several names were proposed after the discovery, including Janus and Oceanus; Le Verrier proposed Neptune, which subsequently became internationally accepted. Parallel international forms include Danish Neptun, Swedish Neptunus, German Neptun, Dutch Neptunus, French Neptune, Italian Nettuno and English Neptune.