Issue 155
WELCOME
“Earth was just a hot rock in a lifeless star system”
Major Tim Peake, our interviewee this issue, touches on the theme of our cover feature in this new-look issue of How It Works: that life in the universe is an incredibly rare phenomenon. It makes our planet, which is an oasis for a huge variety of life forms, including intelligent life, a very special place indeed. We’ve explored the evolution of Earth over its 4.5-billion-year history, the formation of life, landmasses and its changing atmosphere. It’s an amazing story, especially when you consider the many freak cosmic accidents and flukes of nature that without which Earth might have ended up a barren rock like Mars or an otherwise completely different place today. Enjoy!