As reported at the Washington meeting of the American Astronomical Organization, NASA's Kepler telescope has discovered its first five exoplanets -- Kepler's goal is to find planets of Earth-like characteristics.
The smallest is the size of Neptune and the largest is larger than Jupiter, the largest planet in the solar system. The telescope has found these exoplanets by measuring the reflections of the stars. In fact, when the planets pass in front of the stars, part of the light emitted by the stars is interrupted in some way, so their brightness decreases until the planet passes.