Scientists believe that Voyager 1 has crossed the invisible border around our solar system and become the first human-made object to go, in those famous words, where no one has gone before.
According to CNN, experts at NASA have "strong evidence" that Voyager 1 has crossed through the heliosphere -- the magnetic boundary that separates our solar system from the rest of the Milky Way galaxy -- to enter interstellar space.
Ed Stone, head of the the Voyager mission, said, "In leaving the heliosphere and setting sail on the cosmic seas between the stars, Voyager has joined other historic journeys of exploration: The first circumnavigation of the Earth, the first steps on the Moon ... That's the kind of event this is, as we leave behind our solar bubble."
Although it was reported as far back as last year that Voyager was leaving the solar system, NASA made it official today (Sept. 12). You may have heard other reports that Voyager 1 had made the historic crossing before, but Thursday was the first time NASA announced it.
The space agency said that instrumentation used to measure the density of the medium around the craft could calculate its approximate location and whether it had emerged from the heliosphere (that's the simple way of putting it -- CNN has a lot more technobabble).
With the density of electrons in interstellar space thought to be between 0.05 and 0.22 per cubic centimeter, measurements taken last spring indicated that Voyager 1 was at the time in a region with an electron density of around 0.08.
The specific date of Voyager's exit from local space is still not confirmed, but now that the spacecraft is on its way, it's got a new mandate. Stone said, "We're now on the first mission to explore interstellar space. We will now look and learn in detail how the wind which is outside, that came from these other stars, is deflected around the heliosphere."
Voyager 1 and Voyager 2 were both launched in 1977. Voyager 1 is now 11.7 billion miles from Earth, while its sister is 9.5 billion miles from home and three or four years away from its own trip out of the heliosphere. Although it took just three and a half decades for the first Voyager to leave the solar system, it won't make it to another star for another 40,000 years.
Unless it collides with an alien space probe along the way and becomes V'Ger ...