For the approximate values star mass = 1 solar mass ~ 2 x 10^(30) kg planet mass = 1 Jup mass ~ 2 x 10^(27) kg = (1/1000) star mass and parameters R = planet's orbital radius d = distance from Sun to system we can compute the angular semi-major axis of the star's reflex motion around the center of mass: R 1 pc theta ~ 1 mas * (-------) * (-------) 1 AU d (This is one of the few times that the traditional astronomical units of AU and pc make the calculations much easier than the SI units)