重量较大的氧来自某种自然过程，在此过程中，大部分的轻同位素留在了形成太阳的部分星云中。
And the heavier oxygen from a natural process that left more of the light isotope in the part of the nebula that made the sun.
科学家认为重氮来自一颗彗星，而重氧则是来自行星形成的自然过程，这一过程把更轻的氧同位素留在了星云中，形成了太阳。
Scientists say the excess heavy nitrogen could have come from a comet. And the heavier oxygen from a natural process that left more of the light isotope in the part of the nebula that made the sun.
太阳系形成于一个巨大的旋转星云——太阳系星云，星云中含有大量的星际残骸。
Our solar system arose from a large, rotating cloud of interstellar debris called the solar nebula.
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