If the quest for exoplanets excites us so much, it's because it holds in promise the hope of maybe one day finding life elsewhere, life that was born in the light of another sun. It makes you dizzy just to think about it. What a shock it would be for humanity to discover that we are not alone in this Universe!

At the dawn of the third millenium, we're accustomed to talking about the vastness of the Universe. Infinity is almost ordinary. The latest generation of telescopes delivers images of the furthest jewels in the Universe to us. We're on first name terms with primordial galaxies, the first to have formed after the Big Bang. Bit by bit, we're putting together the history of the Cosmos. It's a tough job, but it can be done thanks to the progress in science since the beginning of the twentieth century and to the genius of people like Georges Lemaître, Alexander Friedman and Edwin Hubble, who showed that the Universe is not static, that it's expanding like a soufflé. The consequences of this discovery are nearly as infinite as the Universe itself. Because if it's getting bigger, then it must have been smaller when younger, it even had to have been born, from a ‘singularity’, as the experts say.