The speed of light is a limiting speed of starships. Einstein's theory also deals with time. According to Einstein, as a starship's speed approaches the speed of light, the passage of time slows with respect to the launch site where the mission began. Those on board the starship grow older more slowly than those remaining on the home planet. Authors writing about trips to the stars often violate Einstein's theory when they speak of faster than light propulsion, warp drive, alternate universes, and other means of placing the setting of their story at light year distances from Earth.
Centripetal force is the force that causes a mass to travel in an arc or circular orbit.
It is equal to the object's mass times its tangential velocity squared divided by the radius of the arc or circular path. The pulling away is a result of Newton's First Law. Every particle of matter in the universe attracts every other particle with a force proportional to the product of the masses of the particles and inversely proportional to the square of the distance between them. Newton's law of universal gravitation is often ignored in sci-fi art. To show a hovering flying saucer, suspended above a planet's surface without visible rocketry, rotating propellers or helicopter rotors is a violation of Newton's law of gravitation.