That means the star will make a small circle — what's called reflexive motion.

这意味着恒星会转出一个小圆圈——这被称为自反运动。

Another way is to measure the Doppler shift in a star's light due to reflexive motion as the planet orbits.

另一种方法是测量恒星光线的多普勒频移，这种频移是由行星绕轨道运行时的自反运动引起的。