Thalassa
A regular moon of Neptune about 80 km across, one orbit every 0.31 days.
Where it is right now
Thalassa is in Pisces, 29.3 AU away.
Computed for 2 August 2026, 17:00 UTC, and recomputed at least hourly. This page is cached, so treat the line above as accurate to the hour rather than to the second. The map shows the live position.
Position from a Kepler propagation of the published elements below, accurate to about an arcminute.
Facts
Every line carries the source it came from.
- Mean radius
- 40 kmSource: NASA/JPL Planetary Satellite Physical Parameters
- Orbits
- Neptune, 50,100 km out on averageSource: NASA/JPL Planetary Satellite Mean Elements
- Orbital period
- 0.31 daysSource: NASA/JPL Planetary Satellite Mean Elements
- Orbit shape
- eccentricity 0.0000, inclined 0.20 degrees to Neptune's Laplace planeSource: NASA/JPL Planetary Satellite Mean Elements
- Discovered
- 1989 by Voyager Science TeamSource: NASA/JPL Planetary Satellite Discovery Circumstances
Physical size
- Mean radius
- 40.0 km
- Diameter
- 80 km across
Orbit
Elements are relative to Neptune.
- Average distance from Neptune
- 50,100 km
- Eccentricity
- 0.0000, almost perfectly circular
- Inclination to Neptune's reference plane
- 28.77 degrees
- Orbital period
- 7.5 hours
- Longitude of ascending node
- 49.45 degrees
- Argument of periapsis
- 106.12 degrees
- Mean anomaly at J2000.0
- 165.70 degrees
Family
Orbits Neptune.
Claim this body
$15 once, and it stays yours
A real catalogued body with a real name.
A claim is a listing on this map. Not an IAU designation. Permanent, with one disclosed exception for dead links: see the terms.
Catalog id thalassa. 3,172 objects on the map, of which 171 are hand-authored with sourced facts.