Figure 6. Pinwheel Galaxy, Marking of arms and 8quadrants (https://en.wikipedia.org/wiki/Pinwheel_Galaxy#:~:text=%20%20%20% 20Pinwheel%20Galaxy%20%20,m%2012.6%20s%20%2013%20more% 20rows%20)

From

The Galaxies and the Dark Matter

José Luís Pereira Rebelo Fernandes

International Journal of Physics. 2021, 9(1), 36-41 doi:10.12691/ijp-9-1-4