"Above us, stars. Beneath us, constellations." I was thinking about this sentence for a while. In regards to images -- above is individuals in a distance, and beneath is a collection in the distance. What does that mean? Well, this poem is a comparative poem like the next two lines, "Five billion miles away, a galaxy dies / like a snowflake falling on water."
For me, everything stated so far is something I cannot grasp -- literally. Stars, constellation, galaxy -- so far off, so much imagined imagery. Even the snowflake falling on water, which seems like something to hold on to, disappears.
But then the poem goes into a very specific scene:
[...] Below us,
some farmer, feeling the chill of that distant death,
snaps on his yard light, drawing his sheds and barn
back into the little system of his care.
"A chill of that distant death" seems a bit sarcastic. Something unable to grasp and just going back to the usual thing of "snaps on his yard light." However, I take the chill as genuine -- or rather, there was a thought that happened that sobered up the farmer. "little system of his care" brings in a comparative analogy of our own little galaxy -- everyone being celestial.
This idea ends out the poem, "All night, the cities, like shimmering novas, / tug with bright streets at lonely lights like his." Being celestial doesn't mean not feeling alone -- loneliness occurring in individual galaxies -- individuals.