It is about 8 times the mass of Earth, and located in an orbit just right for liquid water to exist on the surface.
它大概是地球质量的8倍而且它所在的轨道恰好有益于在其表面有液态水的存在。
As another example the center of mass of the earth and moon moves in an approximately circular orbit around the sun.
作为另一个例子，地球和月亮的质心就是在一个绕太阳的近似的圆轨道上运行。
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