26. Has Earth always had enough oxygen to support life? Does any oxygen on Earth come from space? (A K2S Question)

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(RR) About two or three billion years ago, there was a vast change in climate on the Earth, marked by a great increase in oxygen levels on the planet. This was likely caused by algae and photosynthetic bacteria. And today, it goes on. Almost all of the Earth's oxygen comes from the upper layers of plant life in the oceans and shore areas on the planet. There is water in space, which is one source of oxygen on Earth. It's been found on comets, Jovian worlds, and lots of other places. The oxygen molecule has been found, too, in large gas clouds in the galaxy, called the nebulae. Response credit to Russell Romanella (RR) Response credit to Lonnie Moffitt (LM)

Answer provided by Lonnie Moffitt & Russell Romanella


Image:K2S logosmall.jpg Question and Answer extracted from the book Kids to Space - by Lonnie Schorer


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