This is a simulation of the Proportional Navigation guidance law. In simplified terms, the missile always tries to keep its target at the same heading in its field of view. This results in the velocity of the missile (relative to the target) pointing at the target. Dial: Red = Missile/Thrust Direction Green = Missile Absolute Velocity Blue = Direction from Missile to Target Purple = Missile Velocity Relative to Target https://en.wikipedia.org/wiki/Proportional_navigation