It is clearly her presentation of night and moonlight that make these aspects memorable. Consider the imagery that Adrienne Rich employs and the strength of her description that brings night and moonlight to life. You might want to consider how moonlight is personified:
on the ground, moonlight picking at small stones
as it picks at greater stones as it rises with the surf
laying its cheek for moments on the sand
as it licks the broken ledge, as it flows up the cliffs,
as it flicks across the tracks
as it unavailing pours into gash
of the sand-and-gravel quarry
as it leans across the hangared fuselage
of the crop dusting plane
as it soaks through cracks into trailers
tremulous with sleep
as it dwells upon the eyelids of sleepers
as if to make amends.
Note the various actions that are associated with moonlight: it is shown to spread across everything, "soaking" through layers and materials and "dwelling" upon those who are asleep as if it wants to "make amends" for some unspecified wrong that it has committed. Therefore personifying the moonlight and giving it human actions, making it appear like a person or a creature that can roam the night creates an unforgettable image of moonlight through its presentation and description.