Solar radius 太阳半径
Solar radius is a unit of distance used to express the size of stars in astronomy. The solar radius is usually defined as the radius to the layer in the Sun's photosphere where the optical depth equals 2/3:
The solar radius is approximately 695,700 kilometres (432,288 miles), which is about 10 times the average radius of Jupiter, 110 times the radius of the Earth, and 1/215th of an astronomical unit, the distance of the Earth from the Sun. It varies slightly from pole to equator due to its rotation, which induces an oblateness in the order of 10 parts per million. (See 1 gigametre for similar distances.)