astronomers have spotted the smallest extrasolar planet yet. Designated OGLE-2005-BLG-390Lb, the planet is five times as massive as Earth and sits three times farther from its host star than Earth lies from the sun. With its large orbit and relatively cool parent star, the planet is thought to have a Pluto-like surface temperature of minus 364 degrees Fahrenheit. Researchers describe the find in detail in the current issue of Nature.