To make a rotation curve one calculates the rotational velocity of stars along the length of a galaxy by measuring their Doppler shifts, and then plots this quantity versus their respective distance away from the galactic center.

• 沿着银河的长度通过测量它们的多普勒变换计算星系的旋转速度的旋转曲线,然后绘出它们分别远离银河中心的距离。