Worlds Without End
Chris Impey
MIT Press £27 • HB
As recently as the early 1990s our Solar System contained the only planets known to us and Earth seemed the only possible haven for life. To say that theas an indicator of habitability. Indeed, observations of our stellar neighbourhood so far point to there being more planets than stars. This means we might expect several hundred billion planets in our own Galaxy and perhaps similar numbers in other galaxies across the Universe. With so many planets out there, is Earth really that unique after all?
