Although some of these nebulas appear like planets on the sky (hence their name), they actually surround stars far outside our Solar System.
虽然这一类星云看起来象是天空中的行星(也因此而得名)，实际上它们所环绕的恒星远在我们太阳系之外。
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This assumption think that all of the Earth and the moons are the nebulas which floats in the solar systems through revolving and absorbing to accumulate and become a star body in the meantime.