Astronomers have discovered a planet somewhat larger and more massive than Neptune orbiting a star 120 light-years from Earth. While Neptune has a diameter 3.8 times that of Earth and a mass 17 times Earth's, the new world (named HAT-P-11b) is 4.7 times the size of Earth and has 25 Earth masses. HAT-P-11b was discovered because it passes directly in front of its parent star, thereby blocking about 0.4 percent of the star's light. This periodic dimming, called a transit, was detected by a network of small, automated telescopes known as "HATNet," which is operated by the Harvard-Smithsonian Center for...