Solar luminosity

Unit of light in stars and galaxies

The solar luminosity (L☉) is a unit of radiant flux (power emitted in the form of photons) conventionally used by astronomers to measure the luminosity of stars, galaxies and other celestial objects in terms of the output of the Sun. One nominal solar luminosity is defined by the International Astronomical Union to be 3.828×1026 W. This corresponds almost exactly to a bolometric absolute magnitude of +4.74. The Sun is a weakly variable star, and its actual luminosity therefore fluctuates.

From Wikipedia, under CC BY-SA. More on occurri.