Angular distance

Angular distance or angular separation, also known as apparent distance or apparent separation, denoted ${\displaystyle \theta }$, is the angle between the two sightlines, or between two point objects as viewed from an observer.

Angular distance appears in mathematics (in particular geometry and trigonometry) and all natural sciences (e.g., kinematics, astronomy, and geophysics). In the classical mechanics of rotating objects, it appears alongside angular velocity, angular acceleration, angular momentum, moment of inertia and torque.