The Earth Shaker Poseidon
As evidenced by other translators of Homer’s work, this line sometimes includes the Earth Shaker’s more popular name, Poseidon. With control over the sea, Poseidon has an important role in Odysseus' journey. Often across cultures, the god's names were changed. Neptune was the name Romans gave to Poseidon.


http://www.poetryintranslation.com/PITBR/Greek/Odyssey5.htm
http://www.mythweb.com/encyc/entries/poseidon.html