In some sense the Voyager spacecraft have been leaving the solar system since launch. :) As the Nature article points out, Voyager 2 crossed the termination shock in 2007, entering the heliosheath. The recent announcement is about Voyager 2 exiting the heliosphere and entering interstellar space. Here's a nice graphic that shows the various regions - https://www.nasa.gov/sites/default/files/thumbnails/image/pi...