Kepler has been successfully launched, and over the next three and a half years it will look at a single patch of sky in search of planets. The spacecraft is sensitive enough to detect the existence of planets even as small as our own puny planet, Earth. It does it by detecting the very slight dimming of starlight as a planet moves in front of its parent star. It also looks at many stars at once so that it astronomers would not have to pick a star at random, just hoping that the planet’s orbital plane is at the right inclination and that the planet just passes in front of the star when Kepler is looking at it. With orbital periods of a year or more like our own Earth, keeping watch of many stars at once would have to be the way to go.
