A big moon likely could have helped stabilize Mars' orbit, but the planet has just two small moons, most likely captured asteroids, that don't have much gravitational muscle.
一个月亮很可能帮助稳定火星的轨道，但是它也有两个小的卫星，很可能是被捕获的小行星，他们根本就没有足够的引力能束缚。
That means that, even if the planet has terrestrial moons, they likely wouldn't be able to stand the extreme temperature swings that go along with Epsilon Eridani b's eccentric orbit.
这意味着，即使这个星球有类似地球的卫星，它们也不可能承受得了天苑四b椭圆轨道带来的极端温度变化。
Seen here with its three known moons, Charon, Nix, and Hydra, Pluto is a member of a group of objects that orbit in a disklike zone beyond the orbit of Neptune called the Kuiper belt.
这里可以看见它的已知3个卫星：冥卫1，冥卫2，和冥卫3。 包括冥王星在内的一群物体，在海王星的凯伯带（数十亿颗在海王星轨道之外绕行的小型冰体构成的碟形带）之上，围绕着太阳的作盘形轨道运行。
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