Guest Post: Building a habitable planet

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NASA

‘How to build a habitable planet’ is the title of a popular American college textbook which tells the story of the Earth from ‘The big bang to humankind’. It’s a big book – because it is a long story. All the evidence we have suggests that in its infancy the Earth was a most inhospitable planet and not very different from its near neighbours. Back then it had a transient volcanic landscape, a carbon-dioxide-rich greenhouse atmosphere and was periodically bombarded with asteroids from space. In contrast today we see a planet with mobile tectonic plates, oceans, continents, an oxygenic atmosphere and teeming with life, fundamentally different from Mercury, Mars or Venus. So, why? What is it about the history of the Earth which makes it so different now from its near neighbours? Continue reading