“Perhaps life is rare, either because the precise conditions necessary for it to occur are uncommon or because the chances of it arising are so vanishingly improbable that the Universe just hasn’t been around for long enough. Some scientists argue that the Earth may be a rather exceptional planet after all, with its large, stabilising moon and uncommonly well-behaved sun. We may even lie in a peculiarly habitable part of the galaxy, central enough to benefit from the chemical enrichment of previous generations of stars but safely distant from the harsh radiation of the galactic core. In this case we might not be the only life forms in the Universe, but we could be among the first.”