AU Astronomical Unit天文单位
astronomical unit distance天文单位距离
light-time for astronomical unit distance天文单位距离的光行时
N(名词) a unit of distance used in astronomy equal to the mean distance between the earth and the sun. 1 astronomical unit is equivalent to 1.495×1011 metres or about 9.3×107 miles 天文单位; 天文学中的距离单位,代表从地球到太阳的距离