"The Voyager 1 spacecraft launched in 1977 on a mission to Jupiter and Saturn. It kept on going. Today it's billions of miles from Earth, and scientists have been predicting it will soon leave the solar system."

"NPR has been on Voyager watch since at least 2003, when longtime science correspondent Richard Harris provided this warning of Voyager's impending departure."

"But now Marc Swisdak, a physicist at the University of Maryland, says the spacecraft may have already left. "Late July 2012 is when we think it [left]," Swisdak says."

"How did we miss that? As it turns out, it wasn't entirely our fault. Researchers thought the solar system was surrounded by a clearly marked magnetic field bubble."