Great Oxidation Event

Curious Kids is a series for children of all ages. If you have a question you’d like an expert to answer, send it to curiouskidsus@theconversation.com. Will the Earth last forever? – Solomon, age 5, California Everything that has a beginning has an end. But the Earth will last for a very long time, and its end will come billions of years after anyone who is alive here now is gone. Before we talk about the future of our planet, let’s review its history and when life appeared on it. The history of human beings is very, very short compared with that of Earth. 4 billion years old Our planet formed from a giant cloud of gas and dust in space, which is called a nebula, about 4.6 billion years ago. The first continent might have formed on its surface as early as 4.4 billion years ago. The atmosphere of the early Earth did not contain oxygen, so it would have been toxic to hum...