Planet hunters have found 28 new worlds orbiting distant stars, bringing the total number of so-called exoplanets to 238, according to a presentation at the American Astronomical Society meeting this week. Researchers also singled out a Neptune-mass planet [above] they discovered two years ago. Based on its density and distance from its star—the red M dwarf Gliese 436 (GJ 436), 30 light-years away—they infer that it is a giant ball of hot rock and ice kept solid by high pressures. Currently, astronomers think they can only see very large planets, but as detection methods advance, they expect to find smaller, more Earth-like worlds, too.