There seems to be a sign error in the radial position of Alpha Centauri (= Toliman = Rigil Kentaurus) A and B. Celestia shows the dimmer component B being closer to the Sun than A: Just fly to alpha Cen A and look back to Sol, then star B is in the field of view.
However, according to radial velocity curves and orbital parameters given by Pourbaix et al. (2002; see http://arxiv.org/abs/astro-ph/0202400\) and discussed in Wikipedia (http://en.wikipedia.org/wiki/Alpha_Centauri and discussion page therein) component B is currently more distant than A, and B's radial velocity has been positive with respect to A (and less negative absolutely since the center of mass of A+B has a negative RV) since about 1960 and until approx. the beginning of the 2000's. This error cannot be due to the travel time of the light which is only about 4.4 years, i.e. much shorter than the half-orbit period (40 years).
Therefore, I suggest to flip the radial distance and radial velocity components of Alpha Centauri A and B to get this right. The issue does not affect Proxima Centauri.
I have installed Version 1.61 Mac OS-X
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