previous post that there is not much more to be said but, of course, I cannot do better than to quote directly from Poul Anderson's own description of the nebula where a star and its planetary system are condensing:
"Flandry himself saw sinister grandeur: great banks and clouds of blackness, looming in utter silence on every side of him, gulfs and canyons and steeps, picked out by the central red glow. He knew, objectively, that the nebula was near-vacuum even in its densest portions: only size and distance created that picture of caverns beyond caverns. But his eyes told him that he sailed into Shadow Land, under walls and roofs larger than planetary systems, and his own tininess shook him."
-Poul Anderson, Sir Dominic Flandry: The Last Knight Of Terra (New York, 2012), p. 284.
- as when, millennia later, Daven Laure sails into the Cloud Universe nebula (see also here, here and here), except that that one is many times bigger, containing over a quarter of a million stars, some condensing, some going nova, others at every intermediate stage.
It is the "...walls and roofs larger than planetary systems..." that are truly awesome, generating the impression that this is not interstellar space but a vast three-dimensional material structure, like a cathedral explored by a fly.
To its credit, the very first Star Trek feature film showed the Enterprise dwarfed by some sort of interstellar cloud that it had to pass through.