Non-gravitational Acceleration
Acceleration caused by forces other than gravity, like a comet's outgassing or solar radiation, which alters an object's hyperbolic path beyond simple gravitational orbits.
Non-gravitational acceleration refers to the change in an object's velocity caused by forces other than gravity, such as outgassing from a comet's surface, solar radiation pressure, or magnetic fields. In astronomy, it explains hyperbolic trajectories or speed anomalies in objects like interstellar comets that do not follow paths dictated solely by gravitational attraction to a star.
What this means in real life
A car speeding up on a flat road experiences non-gravitational acceleration from its engine; a satellite firing thrusters to change orbit also accelerates non-gravitationally, separate from Earth's pull.
What it isn’t
It is not the same as 'zero gravity' or weightlessness. An object in free fall experiences zero apparent weight but still undergoes gravitational acceleration; non-gravitational acceleration is any additional push or pull from other sources.
Commonly misused online
Often conflated with 'antigravity' in sci-fi discussions, but non-gravitational acceleration simply means forces other than gravity are at work—not that gravity is being cancelled or reversed.