It started out as an unguided air-to-air rocket. Then, someone had the idea to put a sensor on it that could pick up the heat put out by an airplane's engine. Add a control system and you've got yourself an effective, deadly missile — one that has been relied upon for decades by American pilots and their allies.
The United States Navy tested if the Sidewinder could kill tanks. (US Navy photo)
The AIM-9X will be around for a long time, with an improved version of the missile slated to enter service in 2022.
Learn more about the Sidewinder in the video below: