re: Question about the math
Earth's orbit around the Sun causes a 0.09 m/s doppler shift in the Sun's light, because the Sun wobbles slightly as the Earth goes around. Now scientists at JPL say they can measure micro-arcsecond wobbles in distant stars with their new apparatus. I'm assuming they are referring to the displacement of the Star as it wobbles rather than the doppler shift. How is micro-arcsecond resolution equated mathematically with the known 0.09 m/s doppler shift from a terrestrial planet?