Solar radius

Common card · No. 207483

A solar radius is a unit of distance, commonly understood as 695,700 km and expressed as R⊙, used mostly to express the size of an astronomical objects relative to that of the Sun, or their distance from it. This length is also called the nominal solar radius. The sun's actual radius, from which the unit of measurement is derived, is usually calculated as the radius from the sun's center out to the layer in the Sun's photosphere where the optical depth equals 2/3. One solar radius can be described as follows:1R⊙=6.957×108 mThis is an approximation: both because such distance is difficult to measure and can be measured in various ways, and because the sun is not a perfectly spherical object itself, and thus the actual radius varies depending on the point(s) measured and modality of measurement employed. 695,700 kilometres (432,300 miles) is approximately 10 times the average radius of Jupiter; 109 times the 6378 km radius of the Earth at its equator; and 1215 or 0.0047 of an astronomical...

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