NASA's Voyager probe crossed into interstellar space last year according to a new study released this week. This means Voyager is the first man-made object to leave the solar system.
Voyager 1 crossed on July 27, 2012 according to SPACE.com.
"It's a somewhat controversial view, but we think Voyager has finally left the solar system, and is truly beginning its travels through the Milky Way," lead author Marc Swisdak of the University of Maryland said in a press statement.
Swisdak and his co-authors Merav Opher and James Drake are not Voyager mission scientists.
Voyager 1 and Voyager 2 launched just weeks apart in 1977 to "study Jupiter, Uranus, and Neptue" according to SPACE.com. After completing its studies, the two probes kept flying toward interstellar space.
Voyager 1 is about 11.6 billion miles from Earth, and Voyager 2 is 9.4 billion miles away.
Not everyone believes that Voyager has crossed however, like Voyager lead scientist Edward Stone.
"We know where Voyager is in terms of distance and we know what it is observing. The challenge is relating that to these complex models of the interaction between the interstellar medium and the heliosphere," Stone said, according to Reuters.
Voyager 1 will begin running out of energy in 2020, and around 2025, it will be completely out of power.