Frank notes that the objects are also seen in consecutive frames, revealing not only the predicted dawn-to-dusk streaming motion
but expansion of the water-vapor cloud.
Before the 1970s, astronomers didn't believe galaxies had any large-scale streaming motion other than the velocity associated with the expansion of the universe.
They observed galaxies on the opposite side of the sky from the proposed Great Attractor and found a coherent streaming motion of these galaxies toward the same concentration.
Mathewson told Science News that based on his latest, unpublished data, even the very distant concentration of mass known as the Shapley concentration -- believed to lie about 450 million light-years from our galaxy -- isn't far enough away to explain the large-scale streaming motion. Indeed, Mathewson says he is so uncomfortable about the size of the proposed, unmapped mass that he would prefer to believe there is no river at all.
Wang speculates that the streaming motion
of gas from a cluster of massive stars created winds strong enough to sculpt the honeycomb.
So that a metonymic motion across the possible inventory of things seen in a specific time and place, say Brooklyn in the 1850s, while standing motionless on a moving boat, is attended by an emphasized motion across the material space of the page and the line in order to return to more such streaming motions
. One crosses a line that tells of a crossing but, just as the poem's title fantasizes that the crossing is eternal, one ends up at the beginning again.
Vogel of Rensselaer Polytechnic Institute in Troy, N.Y., and colleagues at the California Institute of Technology in Pasadena report the first wide-scale mapping of molecular gas in a classic spiral galaxy "with sufficient resolution to resolve the molecular cloud complexes and their streaming motions