Neptune IV - 1989N5


Thalassa appears to be about 80 kilometers (50 miles) in diameter. It orbits Neptune in 7 hours, 30 minutes about 25,200 kilometers (15,700 miles) above the cloud tops. It is irregularly shaped and shows no sign of any geological modification. Thalassa circles the planet in the same direction as Neptune rotates. The above image has been slightly smeared so that Thalassa appears highly elongated.

Thalassa Statistics
 Discovered byVoyager 2 
 Date of discovery1989 
 Mass (kg)
 Equatorial radius (km)40 
 Equatorial radius (Earth = 1)6.2716e-03 
 Mean density (gm/cm^3)
 Mean distance from Neptune (km)50,000 
 Rotational period (days)
 Orbital period (days)0.311485 
 Mean orbital velocity (km/sec)11.68 
 Orbital eccentricity0.0002 
 Orbital inclination (degrees)0.21 
 Visual geometric albedo0.06 
 Magnitude (Vo)23.8 


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