The folks monitoring the Voyager 1
spacecraft have determined that it has left the solar system. Meaning that the spacecraft has left the part of the solar system influenced by the outward press of the solar wind. Voyager 1 is currently about 125.5 AU from the Earth and a similar distance away from the Sun. This equates to 18.7 billion kilometers away, give or take. You can see where the Voyager 1 and Voyager 2 spacecraft are right at the moment by going here
. Both Voyager spacecraft were launched in 1977 destined to make "Grand Voyage"s through the solar system. They collected data and close-up pictures of the outer planets (Jupiter, Saturn, Uranus & Neptune) and used momentum transfer during their passes of the large planets to reach the highest velocities of any man-made craft for their time (17 km/sec or 61000 km/hour). NOTE: The Helios Spacecraft have reached higher velocities since, but did so by diving towards the sun along highly elliptical orbits and remaining bound to the solar system, so in a way, that's sort of cheating.
Voyager 1 is now travelling through the cooler, denser plasma of interstellar space. While Voyager's nuclear batteries may allow it to operate until 2020, it's journey will continue onward. In 14,000 years, it will pass beyond the Oort cloud. It will make it's closest approach to one of our neighboring stars in 40,000 years. Congratulations to the Voyager team for a job well done. Thank you for your service of scientific discovery.