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Evolution of the solar luminosity, radius and effective temperature compared to the present-day Sun. After Ribas (2009) [3] The uncrewed SOHO spacecraft was used to measure the radius of the Sun by timing transits of Mercury across the surface during 2003 and 2006. The result was a measured radius of 696,342 ± 65 kilometres (432,687 ± 40 miles).
The Sun's rays are attenuated as they pass through the atmosphere, leaving maximum normal surface irradiance at approximately 1000 W/m 2 at sea level on a clear day. When 1361 W/m 2 is arriving above the atmosphere (when the Sun is at the zenith in a cloudless sky), direct sun is about 1050 W/m 2 , and global radiation on a horizontal surface ...
The angular diameter of the Earth as seen from the Sun is approximately 1/11,700 radians (about 18 arcseconds), meaning the solid angle of the Earth as seen from the Sun is approximately 1/175,000,000 of a steradian. Thus the Sun emits about 2.2 billion times the amount of radiation that is caught by Earth, in other words about 3.846×10 26 watts.
where G is the Newtonian constant of gravitation, M ☉ is the solar mass, k is the numerical value of Gaussian gravitational constant and D is the time period of one day. [1] The Sun is constantly losing mass by radiating away energy, [54] so the orbits of the planets are steadily expanding outward from the Sun. This has led to calls to ...
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]
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.
This result is in pascals, equivalent to N/m 2 (newtons per square meter). For a sheet at an angle α to the Sun, the effective area A of a sheet is reduced by a geometrical factor resulting in a force in the direction of the sunlight of: = ().
332 946 M E ; 1 047.35 M J (Jupiter mass) It is also frequently useful in general relativity to express mass in units of length or time. M ☉ G / c 2 ≈ 1.48 km (half the Schwarzschild radius of the Sun) M ☉ G / c 3 ≈ 4.93 μs; The solar mass parameter (G·M ☉), as listed by the IAU Division I Working Group, has the following estimates ...