Earth protects itself from the sun. The David and Goliath story of Earth's relationship with its greatest threat, our seemingly benign Sun. The Sun is the big violent boss of the Solar System, throwing out devastating particles and energy. Without several shields, one generated by our unique planetary core, another by our atmosphere, and a third by our interconnected weather systems… life on Earth would never have survived.

The freak accident behind complex life. All life on earth started as single cell bacteria and stayed like that for 2 billion years. Successfully spreading across the planet. So even if we do find alien life, what are the chances of that life being complex – like us? Vanishingly rare… on our strange rock, it's all down to a freak event, which accidentally happened when one cell ate another to create a kind of cellular power pack: mitochondria. This almost miraculous event transforms earth into a complex interconnected food web based on a competition for food. And at the top of the pyramid sits us humans.