(CNN) -- At the edge of the heliosphere, you wouldn't know by looking whether you left the cradle of humanity behind and floated out into interstellar space. You would just see unfathomably empty space, no matter which side of the invisible line you were on.
But scientists now have strong evidence that NASA's
Voyager 1probe has crossed this important border, making history as the first human-made object to leave the heliosphere, the magnetic boundary separating the solar system's sun, planets and solar wind from the rest of the galaxy.
