As extended objects rather than point sources, galaxies show a
wide variety of forms, some due to intrinsic structures, others
due to the way the galaxy is oriented to the line of sight. The
random orientations, and the wide spread of distances, are the
principal factors that can complicate interpretations of galaxy
morphology. If we could view every galaxy along its principal
axis of rotation, and from the same distance, then fairer
comparisons would be possible. Nevertheless, morphologies seen
in face-on galaxies can also often be recognized in more
inclined galaxies (Figure 1). It is only for the highest
inclinations that morphology switches from face-on radial
structure to vertical structure. In general we either know the
planar structure in a galaxy, or we know its vertical structure,
but we usually cannot know both well from analysis of images
alone. Figure 1. Four galaxies of likely similar face-on
morphology viewed at different inclinations (number below each
image). The galaxies are (left to right):