relative circle

例句：

1. 1. The relative radius of the planet Mercury is about 0.387 times that of Earth.
   水星的相对半径大约是地球的0.387倍。
2. 2. The relative radius of the sun to the earth is about 1.496 times that of the moon.
   太阳与地球的相对半径大约是月亮的1.496倍。
3. 3. The relative radius of the earth to the sun is about 1.521 times that of themoon.
   地球与太阳的相对半径大约是月亮的1.521倍。