A guidance system for a missile utilitizes a laser beam source at a missile launch pad to generate a laser beam that is directed towards a target. A sensor on the body of a spinning missile detects radiation scattered from the laser beam, the sensor looking sideways and backward at an angle to the missile's longitudinal axis. Signals generated by that sensor are applied to a missile's guidance system's processing electronics that then determines the distance from the missile to the beam from the width of the signal generated by the sensor due to detecting scattered radiation from that laser beam. Once the distance between the missile and the beam is determined, the missile's guidance system corrects the missile's trajectory to maintain its position at a predetermined distance from the beam.