By Beth Mole
With a zap, a beam of ultraviolet light can blast carbon dioxide into oxygen gas, O2. Because the sun hurls the same radiation, the reaction hints that breathable air could have formed on Earth before the dawn of photosynthetic organisms or even in other CO2-rich atmospheres like those on Mars and Venus, researchers argue in the Oct. 3 Science.
The finding is extremely exciting, says chemist Simon North of Texas A&M University in College Station. Though scientists had theorized that the detritus of a carbon dioxide breakup could include O2, proving it has been extremely difficult. To do it, North says, “the authors have made a beautiful set of challenging measurements.”