So I have two objects, Target and Interceptor. Target's position, direction of movement and movement speed are known, and Interceptor's position and movement speed are also known. Both movement speeds are fixed, and Target will never change course. Both are moving in three dimensions; Interceptor can move in any direction.
I want to figure out which direction Interceptor needs to move in, at its fixed movement speed, to be able to collide with Target as Target moves, as quickly as possible - or, as the case may be, I want to know if it is impossible for Interceptor to collide with Target.
I don't know how to do this, and my Google searches clearly haven't been using the right search terms, because nothing useful comes up. How do I calculate this?