NASA has confirmed that Voyager 1, which was launched on September 5 1977, has finally left the Solar System. Voyager 1 becomes the first manmade object to leave the Solar System, and in 40,000 years it will come within 1.7 light years of star AC+793888, before continuing on its millions-of-years journey to the core of the Milky Way.
Before leaving the Solar System, Voyager 1 was located in the heliopause, a region of space between the heliosphere and interstellar space. In April, Voyager started to detect electron plasma oscillations with around 40 times more energy than inside the heliosphere. Basically, the universe is full of electron-dense plasma that has been ejected from supernova stars — but the heliosphere, a bubble of charged particles emitted by the Sun, stops this plasma from entering the Solar System. ”The increased electron density is very close to the value scientists expected to find in the interstellar medium,” says Don Gurnettof the University of Iowa and Voyager project scientist, co-author of the research paper that finally decided that Voyager had left the Solar System. Through extrapolation of data from the fall of 2012, and the spring of 2013, the paper reports that Voyager 1 technically left the Solar System on August 25 2012.
Voyager’s path out of the Solar System, with various parts of the heliosphere/etc labelled
With Voyager 1 now outside the Solar System, it should return some interesting data that will — at long last — empirically inform us about the interstellar medium. There is also some science to be gathered by Voyager 2, which also launched in 1977, and will soon leave the Solar System via a different route. Voyager 1 has a broken instrument which hindered its ability to fully study the heliosphere and heliopause; Voyager 2 has a full complement of functioning instruments. For more information on Voyager 1, see a previous story that we wrote when we thought it had left the Solar System, but actually it hadn’t.
At 36 years of age, Voyager 1 is now 11.6 billion miles away from the Sun — the most distant human-made object. Even so, 11.6 billion miles is still just 1/500th (or 0.002%) of a light year. At its current pace (38,610 mph or 62,136 kmh), it would take Voyager 1 roughly 200,000 years to reach the nearest possibly habitable planet, Tau Ceti e. If we want to colonize other planets, we either need to leave very soon, or develop a method of traveling much, much faster.