奥尔特云(Oort Cloud)是一个假设包围着太阳系的球体云团,布满着不少不活跃的彗星,距离太阳约50000~100000个天文单位,最大半径差不多为1光年,即太阳与比邻星距离的四分之一。天文学家普遍认为奥尔特云是50亿年前形成太阳及其行星的星云之残余物质,并包围着太阳系。
幸神星是太阳系奥尔特云内的一颗假设的气态巨行星的昵称。
Tyche is the nickname given to a hypothesized gas giant planet located in the Solar System's Oort cloud.
据估计,奥尔特云的边界应在50,000天文单位外,因此该天体依然位于奥尔特云内。
This is still well within the Oort cloud, whose boundary is estimated to be beyond 50,000 AU.
经常有彗星被甩出奥尔特云(在太阳系边缘的彗星群),并靠近地球到肉眼可以观测的距离。
Every so often a comet gets flung out of the Oort Cloud, a swarm of comets on the fringes of the solar system, and gets close enough to Earth for us to see it.
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