กำลังส่องสว่าง

Also known as radiant power

thumb|The Sun has an intrinsic luminosity of . In astronomy, this amount is equal to one [[solar luminosity, represented by the symbol L⊙. A star with four times the radiative power of the Sun has a luminosity of .]] Luminosity is an absolute measure of radiated electromagnetic energy per unit time, and is synonymous with the radiant power emitted by a light-emitting object. In astronomy, luminosity is the total amount of electromagnetic energy emitted per unit of time by a star, galaxy, or other astronomical objects.