NASA says Voyager 1 has become the first spacecraft ever to leave the solar system.
The space agency announced the milestone Thursday and published the details in the journal Science.
Voyager 1 was launched 36 years ago on a tour of the outer planets. NASA says it is now cruising through what scientists call interstellar space, the vast, cold emptiness between the stars.
The spacecraft actually made its exit more than a year ago but NASA scientists say they didn't have enough evidence until recently. Some outside scientists though say they are still not convinced.