[url=http://blog.chron.com/sciguy/2012/10/more-evidence-that-voyager-has-exited-the-solar-system/]Article:[/url] To summarize, we'd officially deem Voyager 1 out of the Solar System once it had crossed the heliopause, the theoretically boundary in which solar wind emanating from the Sun is balanced, and therefore halted, by interactions with stellar wind emanating from other star systems. Generally, I'd post the majority of the article here, but a lot of it is diagrams and pictures, so I can't do that. But this would be an absolutely enormous step for mankind's exploration of the cosmos. This'd be the first time a man-made object as exited the Solar System.