Astro inertial guidance is a navigation system commonly used in spacecraft and missiles. Some synonyms for this term include inertial guidance, celestial-terrestrial guidance, and star tracker navigation. Inertial guidance refers to the use of accelerometers and gyroscopes to track the movement of the spacecraft or missile, while celestial-terrestrial guidance involves using the positions of stars and landmarks on Earth to calculate the location. Star tracker navigation specifically refers to the use of cameras and sensors to track stars and determine the spacecraft or missile's orientation. These different synonyms all refer to similar navigation systems that utilize various methods to guide objects through space.