It is named after Galatea, one of the fifty Nereids of Greek legend, with whom Cyclops Polyphemus was vainly in love.

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.

[12] 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.

[13] 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 1,000 kilometres (620 mi) outside its orbit.