For the first time, a human-built spacecraft has left the solar system and entered deep, cold interstellar space.
NASA confirmed Thursday that the Voyager 1 space probe, launched in 1977, is 19 billion kilometers from the sun and has crossed into an unexplored and unknown frontier.
NASA says Voyager crossed into deep outer space last year, but it took this length of time for the evidence to reach Earth.
NASA scientists call this one of the most significant technological achievements in the history of science.
Voyager will now probe parts of the universe never explored before. If all goes as planned, Voyager will radio back details of its discoveries until 2025, when its nuclear fuel is expected to run out.
Voyager 1 and its twin Voyager 2 took off from Earth in 1977 to explore the planets Jupiter and Saturn. Voyager 2 traveled on to Neptune and Uranus and is still in the solar system while Voyager 1 flew beyond Pluto to its current position.