Its event horizon--theboundary at which nothing, not even light, can escape the monster’s gravitationalpull--is four times as large as the orbit of Neptune,our sun’s outermost planetary satellite.

在它的事件视界，即其边界，没有任何东西可以逃脱这头巨兽的引力，甚至连光也不行。 其引力相当于位于我们太阳系最外层行星轨道的海王星的四倍。

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IF OUR solar system holds so many remarkable moons, then what strange satellite worlds might we find among the billions of planetary systems in the Milky Way?

如果我们的太阳系有着如此多的非凡的星球，那么在天河中数十亿计的行星系中我们将会发现怎样奇妙的行星世界？

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If our solar system holds so many remarkable moons, then what strange satellite worlds might we find among the billions of planetary systems in the Milky Way?

仅太阳系就拥有这么多非凡的卫星，那么银河系中其他数十亿的行星系中我们又会找到怎样奇特的卫星？

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