Thalassa

In Greek mythology, Thalassa ("sea") was a primordial sea goddess, daughter of Aether and Hemera. With Pontus, she was the mother of the nine Telchines. Sometimes, she was thought of as the mother of Aphrodite with Zeus. She was the personification of the Mediterranean Sea.

Alternative: Thalatta, Thalath

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Thalassa is the second moon of Neptune. Thalassa was named after a daughter of Aether and Hemera from Greek mythology. "Thalassa" is also the Greek word for "sea". It was discovered in 1989 by Voyager 2. It is irregularly shaped and shows no sign of any geological modification. Since its orbit is below Neptune's synchronous orbit radius it is slowly decaying due to tidal forces and will one day break up into a planetary ring or impact on Neptune's surface.

• Orbital radius: 50,000 km
• Diameter: 80 km
• Mass: Unknown
• Orbital period: 7 hours, 30 minutes (0.311485 days)
• Orbital inclination: 0.21°

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Thalassa is a fictional planet, a waterworld in Arthur C. Clarke's novel Songs of Distant Earth.

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In biology, Thalassa is a genus of ladybird beetle.