Mother Earth, Gaia, the third rock from the Sun - whatever you call it, this 4.5 billion-year-old planet is the one that we and all known living creatures call home.

Ian is a motivational psychologist and author, based at Loughborough University.

Will is a PhD student at the University of Manchester, studying fossil fish.

Nate is a writer based in Washington State, in the US, who covers science, health and the environment for numerous publications.