爱丁顿光度是吸积天体所能达到的最大光度。天体在吸积周围介质的同时发出辐射，当吸积物质累积到一定程度，辐射压(光压)会阻止物质的进一步下落。此时天体作用在一个粒子上的引力与其受到的辐射压力达到平衡。爱丁顿光度的表达式是：

其中是质子的质量，是电子的汤姆孙散射截面，和分别是太阳的质量和光度。上式表明天体吸积所能达到的光度与其自身质量成正比，并且太阳的爱丁顿光度是其光度的10倍。一般说来，普通恒星的光度远远低于爱丁顿光度，某些X射线双星和活动星系核的光度能够达到爱丁顿光度，伽玛射线暴、超新星爆发可以在短时间内超过爱丁顿光度。

The Eddington luminosity, also referred to as the Eddington limit, is the maximum luminosity a body (such as a star) can achieve when there is balance between the force of radiation acting outward and the gravitational force acting inward. The state of balance is called hydrostatic equilibrium. When a star exceeds the Eddington luminosity, it will initiate a very intense radiation-driven stellar wind from its outer layers. Since most massive stars have luminosities far below the Eddington luminosity, their winds are mostly driven by the less intense line absorption. The Eddington limit is invoked to explain the observed luminosity of accreting black holes such as quasars.