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Galatea (moon)

Moon of Neptune

Field	Value
name	Galatea
image	Galatea moon.jpg
discoverer	Stephen P. Synnott and Voyager Imaging Team
discovered	July 1989
caption	Galatea as seen by Voyager 2 (elongation is due to smearing)
pronounced
mpc_name	Neptune VI
named_after	Γαλάτεια Galateia
adjectives	Galatean
orbit_ref
epoch	18 August 1989
semimajor
eccentricity	0.00022 ± 0.00008
period	0.42874431 ± 0.00000001 d
inclination
satellite_of	Neptune
group	Ring shepherd
dimensions	() × () × () km
mean_radius
volume	~
mass

rotation	synchronous
axial_tilt	zero
albedo	0.08
magnitude	21.9
single_temperature	~51 K mean (estimate)

Galatea , also known as Neptune VI, is the fourth-closest inner moon of Neptune, and fifth-largest moon of Neptune. It is named after Galatea, one of the fifty Nereids of Greek legend, with whom Cyclops Polyphemus was vainly in love.

Discovery

Galatea was discovered in late July 1989 from the images taken by the Voyager 2 probe. It was given the temporary designation S/1989 N 4. The discovery was announced (IAUC 4824) on 2 August 1989, and mentions "10 frames taken over 5 days", implying a discovery date of sometime before July 28. The name was given on 16 September 1991.

Physical properties

Galatea is irregularly shaped and shows no sign of any geological modification. It is likely that it is a rubble pile re-accreted from fragments of Neptune's original satellites, which were smashed up by perturbations from Triton soon after that moon's capture into a very eccentric initial orbit.

Compositionally, Galatea appears to be similar to other small inner Neptunian satellites, with a deep 3.0 micron feature attributed to water ice or hydrated silicate minerals. It has a 0.08 albedo at 1.4 and 2.0 microns, dropping to 0.04 at 3.0 microns, and increasing to 0.12 at 4.6 microns.

Orbit

Galatea's orbit lies below Neptune's synchronous orbit radius, so it is slowly spiralling inward due to tidal deceleration and may eventually impact the planet or break up into a new planetary ring system upon passing its Roche limit due to tidal stretching.

Galatea appears to be a shepherd moon for the Adams ring that is 1000 km outside its orbit. Resonances with Galatea in the ratio 42:43 are also considered the most likely mechanism for confining the unique ring arcs that exist in this ring. Galatea's mass has been estimated based on the radial perturbations it induces on the ring.

Notes

References

Planet Neptune Data http://www.princeton.edu/~willman/planetary_systems/Sol/Neptune/

| access-date = 2008-12-13 | url-status = dead | archive-date = 2013-11-01 | archive-url = https://web.archive.org/web/20131101144111/http://ssd.jpl.nasa.gov/?sat_phys_par

| access-date = 2011-10-26

| url-access = subscription

References

{{OED. galatea
AMIA. (1999). "Transforming health care through informatics".
(2024-05-01). "JWST Spectrophotometry of the Small Satellites of Uranus and Neptune". The Planetary Science Journal.
(2019). "The seventh inner moon of Neptune". Nature.

Info: Wikipedia Source

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