For months, researchers have been arguing about just where in the universe the Voyager 1 spacecraft is. They know its position with precision: the NASA mission, launched on September 5, 1977, is now more than 11 billion miles away. But is Voyager still on home turf -- within the bubble blown by a wind of fast-moving particles that emanate from our sun? Or has the spacecraft crossed over to a whole new domain, exploring the area between the stars, known as the interstellar medium? Scientists just haven’t been able to agree.
The debate can seem like astronomy semantics: whichever side of the boundary the spacecraft is on, it’s new territory to us. Does being on one side or the other matter?