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Evolution of the solar luminosity, radius and effective temperature compared to the present-day Sun. After Ribas (2010) [1] 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.
The solar constant is the amount of power that the Sun deposits per unit area that is directly exposed to sunlight. The solar constant is equal to approximately 1,368 W/m 2 (watts per square meter) at a distance of one astronomical unit (AU) from the Sun (that is, at or near Earth's orbit). [99]
Solar irradiance is the power per unit area (surface power density) received from the Sun in the form of electromagnetic radiation in the wavelength range of the measuring instrument. Solar irradiance is measured in watts per square metre (W/m 2 ) in SI units .
If the extraterrestrial solar radiation is 1,367 watts per square meter (the value when the Earth–Sun distance is 1 astronomical unit), then the direct sunlight at Earth's surface when the Sun is at the zenith is about 1,050 W/m 2, but the total amount (direct and indirect from the atmosphere) hitting the ground is around 1,120 W/m 2. [6]
The Sun has an intrinsic luminosity of 3.83 × 10 26 watts.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 4 L ⊙.
The solar constant includes radiation over the entire electromagnetic spectrum. It is measured by satellite as being 1.361 kilo watts per square meter (kW/m 2) at solar minimum (the time in the 11-year solar cycle when the number of sunspots is minimal) and approximately 0.1% greater (roughly 1.362 kW/m 2) at solar maximum. [1]
tech: power output of P-51 Mustang fighter aircraft 1.9 × 10 6 W astro: power per square meter potentially received by Earth at the peak of the Sun's red giant phase 2.0 × 10 6 W tech: peak power output of GE's standard wind turbine 2.4 × 10 6 W tech: peak power output of a Princess Coronation class steam locomotive (approx 3.3K EDHP on test ...
In 2023, solar power generated 5.5% (1,631 TWh) of global electricity and over 1% of primary energy, adding twice as much new electricity as coal. [65] [66] Along with onshore wind power, utility-scale solar is the source with the cheapest levelised cost of electricity for new installations in most countries. [67] [68] As of 2023, 33 countries ...