The Eddington limit is the maximum luminosity a star (or other luminous object) can have before the outward pressure of its radiation balances or exceeds the inward pull of gravity. If a star shines brighter than this limit, the intense radiation would push its outer layers away, effectively blowing off its own material.
This limit is crucial in stellar astrophysics and is especially important for very massive stars, accreting black holes, and quasars. It defines the point at which radiation pressure—the force exerted by light—can overcome gravitational attraction acting on the star’s outer layers.
When a star approaches the Eddington limit, any further increase in energy output risks driving a powerful stellar wind or mass loss. In extreme cases, this can regulate the growth of black holes or set the maximum mass a stable star can reach.
The Eddington limit sets a natural boundary for the stability of luminous objects and plays a key role in understanding stellar evolution, supernova formation, and active galactic nuclei.