All life on Earth started as single-cell bacteria and stayed like that for two billion years. So even if we do find alien life out there, what are the chances of that life being complex like us? 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 power pack for life. This almost miraculous event transforms Earth into a complex interconnected web based on a competition for food. And at the top of the pyramid sit we humans. Astronaut host – Mae Jemison.

After 665 weightless days in space, NASA's most experienced astronaut, Peggy Whitson, smashes through the atmosphere on her last journey home to planet Earth. With her first steps back on land, she encounters fresh air, blue skies, warm sun, and of course, gravity. With unprecedented filming on board the ISS during Peggy's final mission and with the support of our other featured astronauts, we reveal how their time in space transforms their understanding of our planet's wonders, insights that will change our perspective, too. There is no place like home. Or is there? Just how strange is our rock, and is it really unique in the universe? Astronaut host – Peggy Whitson.