Geometric Properties of Conformal Transformations on $\mathbb{R}^{p,q}$

We show that conformal transformations on the generalized Minkowski space $\mathbb{R}^{p,q}$ map hyperboloids and affine hyperplanes into hyperboloids and affine hyperplanes. We also show that this action on hyperboloids and affine hyperplanes is transitive when $p$ or $q$ is $0$, and that this action has exactly three orbits if $p, q \ne 0$. Then we extend these results to hyperboloids and affine planes of arbitrary dimension. These properties generalize the well-known properties of M\"{o}bius (or fractional linear) transformations on the complex plane $\mathbb{C}$.
Comment: To appear in Geometriae Dedicata, 13 pages, no figures