Pushing the frontier of space exploration, Voyager became the first man-made object to leave the solar system. NASA confirmed Thursday that the spacecraft left the solar system more than a year ago, traveling in the space between stars.
Voyager 1 first launched into space in 1977 to study the outer planets, but after completing its mission in 1989, the craft continued traveling—about 12 billion miles in total. It's now so far away that its radio signals take 17 hours to reach Earth.
"Voyager has boldly gone where no probe has gone before, marking one of the most significant technological achievements in the annals of the history of science," John Grunsfeld, NASA's associate administrator for the Science Mission Directorate, said in a statement.
Officials confirmed Voyager's interstellar journey based on space plasma density evidence. Readings from April/May compared with October/November of last year showed the number of protons occupying every cubic centimeter in space increased by almost 100 times. This has been attributed to Voyager leaving the magnetic fields and particle winds billowing from the sun's surface. Scientists calculate Voyager's departure from the solar system at or around August 25, 2012. Moving at 100,000 miles per hour, Voyager is expected to be near another star in 40,000 years.
Scientists began debating on Voyager's location earlier this year. In March, the American Geophysical Union declared the craft had left the solar system, but NASA was reluctant to agree until the surrounding magnetic fields changed direction. NASA's confirmation Thursday should put the controversy to bed.