Diane Lincoln

Could aliens that breathe helium and hydrogen live on exoplanets throughout the cosmos? 

A new study of life on Earth suggests it’s possible. And if so, that would mean the hunt for life in the universe may need to look beyond oxygen-bathed planets to ones with seemingly inhospitable atmospheres. There is no question that an oxygen atmosphere is conducive to life — after all, it’s what we breathe on Earth. But oxygen isn’t common in the cosmos. It makes up about 0.1% of the mass of the universe. Far more common is hydrogen (92%) and helium (7%). The planet that dominates the solar system is Jupiter and its atmosphere is 90% hydrogen and 10% helium, with just traces of other elements. Rocky planets like Earth, with atmospheres bereft of hydrogen and helium, are only a small component of star systems. 



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