Where are all the aliens? WIRED explains the Fermi Paradox
Our Sun is one of up to 400 billion stars in our Milky Way, itself one of 100 billion galaxies in the universe. Each star is thought to have on average at least one planet in orbit, meaning there are trillions upon trillions of planets in the cosmos. But so far we know of only one – Earth – that has life. Are we really alone?