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. One solar luminosity is equal to the current accepted luminosity of the Sun, which is 3.839×1026 W, or 3.839×1033 erg/s. The value is slightly higher, 3.939×1026 W (equivalent to 4.382×109 kg/s or 1.9×10−16 M☉/d) if the solar neutrino radiation is included as well as electromagnetic radiation. The Sun is a weakly variable star and its luminosity therefore fluctuates. The major fluctuation is the eleven-year solar cycle (sunspot cycle), which causes a periodic variation of about ±0.1%. Any other variation over the last 200–300 years is thought to be much smaller than this.
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Famous quotes containing the word solar:
“Senta: These boats, sir, what are they for?
Hamar: They are solar boats for Pharaoh to use after his death. They’re the means by which Pharaoh will journey across the skies with the sun, with the god Horus. Each day they will sail from east to west, and each night Pharaoh will return to the east by the river which runs underneath the earth.”
—William Faulkner (1897–1962)