Luminosity
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Luminosity is an absolute measure of radiated electromagnetic energy per unit time, and is synonymous with the radiant power emitted by a light-emitting object. In astronomy, luminosity is the total a
The Sun has an intrinsic luminosity of 3.83×1026 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☉.
Apparent magnitude
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Apparent magnitude is a measure of the brightness of a star, astronomical object or other celestial objects like artificial satellites. Its value depends on its intrinsic luminosity, its distance, and
Luminosity
…on the luminosity of the object, the distance between the object and observer, and on any absorption of light along the path from object to observer. Apparent magnitude is a logarithmic measure of apparent brightness. Distance can often be estimated as the luminosity distance if the luminosity is thought to be known…
Asteroid 65 Cybele and two stars in the constellation Aquarius, with their magnitudes labeled
Image of 30 Doradus taken by ESO's VISTA. This nebula has a visual magnitude of 8.