Assymetric galactic rotation curves

Galactic rotation curves are
derived from AVERAGING
the assymetric curves from opposite
sides of a galactic disc.

My explanation is that the
discs are precessing, as well as rotating.

I am unsure of the “official”
explanation.

See how to do Benzene with
discs rotating/precessing at 1:2
users.accesscomm.ca/john/BenzeneE.GIF

If galactic discs precess,
as well as rotate,
then the stars in the disc edge
coming towards us would
be perceived as going faster,
and the stars in the edge receding
from us would appear to go
more slowly.
Thus, the assymetry found in the
rotation curves of most galaxies.

I guess that most galaxies are probably precessing.

Precessing relative to what? :-s

In the case of our galaxy relative to other galaxies of the Local Group and the Virgo Supercluster, if not to more.