Neso (moon)
| Discovery | |
|---|---|
| Discovered by |
|
| Discovered | August 14, 2002 |
| Mean orbital elements | |
| Epoch June 10, 2003 | |
| Semi-major axis | 0.33 AU (~49,500,000 km), 3,220 Neptune radii, 49.285 Gm |
| Eccentricity | 0.5714 |
| Inclination | 136.439° * |
| Orbital period | 9740.73 d (26.67 a) |
| Physical characteristics | |
| Mean diameter | 60 km** |
| dimensions | {{{dimensions}}} |
| Rotation period | ? |
| Albedo | 0.04 assumed |
| Color | ? |
| Spectral type | ? |
|
*to the ecliptic **based on the albedo |
|
*to the ecliptic
Neso (/ˈniːsoʊ/ NEE-soh; Greek: Νησώ), also known as Neptune XIII, is the outermost natural satellite of Neptune. It is an Irregular moon discovered by Matthew J. Holman, Brett J. Gladman, et al. on August 14, 2002, though it went unnoticed until 2003. Neso orbits Neptune at a distance of more than 48 Gm (million km), making it (as of 2015) the most distant known moon of any planet. At apocenter, the satellite is more than 72 Gm from Neptune. This distance is of such an order that it exceeds Mercury's aphelion, which is approximately 70 Gm from the Sun.
Neso is also the moon with the longest orbital period, 26.67 years. It follows a highly inclined and highly eccentric orbit illustrated on the diagram in relation to other irregular satellites of Neptune. The satellites above the horizontal axis are prograde, the satellites beneath it are retrograde. The yellow segments extend from the pericentre to the apocentre, showing the eccentricity.
Neso is about 60 km (37 mi) in diameter based on an assumed albedo, and assuming a mean density of 1.5 g/cm3, its mass is estimated at 2×1017kg.
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