eng Science and Education Publishing International Journal of Physics 2333-4576 2023-09-16 11 4 166 173 10.12691/ijp-11-4-1 IJP20231141 article Hongjun Pan hpan@unt.edu 1 Department of Chemistry, University of North Texas, Denton, Texas 76203, USA This paper illustrates that the ROTASE model proposed by the author for the formation of spiral arms of galaxies is nicely demonstrated by the spirals generated by rockets venting fuel during free fall. The patterns of spirals by the falling rockets strongly support that the spiral galaxies with perfect central symmetry have to be originated from the galactic centers, and the spiral arms and the galactic bars are bound together as ¡°rigid¡± body. The exclusive presence of a rear side trail effect in galaxies indicates the absence of co-rotation, and the rotation of spiral arms is faster than the galactic matters. The exact nature of X-matter remains an open question. http://pubs.sciepub.com/ijp/11/4/1/ijp-11-4-1.pdf spiral arms spiral galaxies x-matter black holes galaxy evolution spirals by rockets