parsec
/ˈpɑːsek/noun
- a unit of distance used in astronomy, equal to about 3.25 light years (3.08 ×1016 metres). One parsec corresponds to the distance at which the mean radius of the earth's orbit subtends an angle of one second of arc.秒差距（天文学距离单位, 1秒差距约等于3.25光年, 即3.08×1016米; 1秒差距对应地球轨道平均半径对向1角秒的距离）。
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