具有相同质子数，不同中子数的同一元素的不同核素互为同位素(Isotope)。而轻同位素（light isotope），是指某一元素中质量较小的核素，相对于质量较大的核素而言的核素。
它们晶体里重轻同位素的比例并不像是从地底挖出来的东西那样。
The ratio between the heavy and light isotopes of the element in their crystals is not quite right for stuff that has come out of the ground.
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.
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. So we are made of star stuff.
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