page_title: Solar luminosity
hierarchical_section_title: Solar luminosity
context_page_description: The solar luminosity, L☉, is a unit of radiant flux 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 does not include the solar neutrino luminosity, which would add 0.023 L☉. The Sun is a weakly variable star, and its actual luminosity therefore fluctuates. The major fluctuation is the eleven-year solar cycle that causes a quasi-periodic variation of about ±0.1%. Other variations over the last 200–300 years are thought to be much smaller than this.
context_section_description: 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 does not include the solar neutrino luminosity, which would add 0.023 L☉. The Sun is a weakly variable star, and its actual luminosity therefore fluctuates. The major fluctuation is the eleven-year solar cycle (sunspot cycle) that causes a quasi-periodic variation of about ±0.1%. Other variations over the last 200–300 years are thought to be much smaller than this.
caption: Evolution of the solar luminosity, radius and effective temperature compared to the present-day Sun. After Ribas (2010)[1]