Having visited all the outer planets except Pluto, they are on their final quest - to locate the shifting boundary between the Sun's domain and the realm where interstellar space begins.
Having visited all the outer planets except Pluto, they are on their final quest - to locate the shifting boundary between the Sun's domain and the realm where interstellar space begins.
它们访问了除冥王星之外所有的太阳系外层行星，目前正在进行最后的探索--确定太阳系与星际空间之间游移不定的边界在何处。