Re: I didn't know that was true! Where did you come across that info?
Uh just general astro knowlege. I read this stuff almost as much as football. :)
The technique you described, astrometrics is old and has a history of detecting planets that do not really exist. Too low signal to noise ratio. Nearly all planets detected have been via spectroscopic detection of dopplet shifts of a few METERS per second, i.e. spped of a fast walk. Amazing!
List of planets found:
http://www.princeton.edu/~willman/planetary_systems/
Mayor, Marcy, Butler ALL use the doppler shift technique.
-philw