Astronomers are beginning to glimpse what exoplanets orbiting distant suns are actually like. The trickle of discoveries has become a torrent. Little more than two decades after the first planets were found orbiting other stars, improved instruments on the ground and in space have sent the count soaring: it is now past 2,000. The finds include 'hot Jupiters', 'super-Earths' and other bodies with no counterpart in our Solar System - and have forced astronomers to radically rethink their theories of how planetary systems form and evolve. Yet discovery is just the beginning. Astronomers are aggressively moving into a crucial phase...
