For there to be life elsewhere in the universe, there would have to be planets similar to Earth, i.e. small, rocky planets orbiting at the right distance from their star to ensure that they are not so hot that water boils and not so cold that it remains frozen. Until now techniques have not been sensitive enough to detect such planets. The new Kepler telescope is so sensitive that for the first time astronomers will be able to see if there are Earth-sized planets in the 'habitable zone' of their stars - the region where the temperature is right for liquid water to exist at the surface. So if the Kepler telescope finds that such planets exist, we can at last be confident that there is life on planets other than Earth.