An Etymological Dictionary of Astronomy and Astrophysics

The second innermost satellite of → Neptune. It was discovered using NASA’s Voyager 2 mission in 1989. It orbits 50,070 km from the center of Neptune and is about 80 km in diameter.

See also: Named after a daughter of Aether and Hemera from Gk. mythology. Thalassa is also the Greek word for “sea”.