< p >这是天文学比地球科学,但年轻的地球,而形成,就很难留江南体育网页版住氢。这有两个原因。一个是< a href = " https://en.wikipedia.org/wiki/Frost_line_(天体物理学)”rel = " nofollow noreferrer " >霜线< / >这意味着有相对较少的氢和相对较少的水和其他气体地球形成的时候。< / p > < p >,另一个是< a href = " https://en.wikipedia.org/wiki/Atmospheric_escape " rel = " nofollow noreferrer " >大气逃逸< / >。地球没有足够的重力保持氢气。事实上,地球仍失去氢,由这个< a href = " http://scitechdaily.com/earth -失去- 50000吨的质量——每一个——year/”rel = " nofollow noreferrer " > < / >估计,每年约95000吨。< / p > < p > < a href = " https://i.stack.imgur.com/tcFNO.png " rel = " nofollow noreferrer " > < img src = " https://i.stack.imgur.com/tcFNO.png " alt = "在这里输入图像描述" > < / > < / p > < p >精确多少氢和水在形成和地球包含多少钱收购太阳风(氢原子核)和彗星和小行星撞击(水和其它气体)还不清楚。我认为这是可能,大多数来自影响,我认为这是倾斜的共识,但一个精确的答案不得而知。< / p > < p >地球氢气和氧气混合后,有相对较小的自由计划中的氧气。氧气结合轻易与许多元素,所以它丰富而不是元素/气态。地球也会失去气态氢和没有氧气,直到大约20亿年前,不太可能多水形成。 When we learn more about exoplanets, we might find that larger/super Earths might retain more hydrogen and form abundant water in that way if they have photosynthesis to create Oxygen, but that's just theoretical. Earth is too small to have retained enough hydrogen to do that in large amounts.