In 2012, NASA’s Voyager 1 probe became the first man-made object to leave the solar system, catapulting itself into the farthest reaches of the universe ever touched by humans — or, it didn’t. Determining the exact borders of our solar system proved controversial. Now, though, we know NASA’s position on the subject: although the probe has yet to leave the solar system, it’s entered interstellar space, a part of the universe the human race has never reached.
Why the waffling? Partly, Voyager 1 seems to be involved in a weird semantic game. The sun emits a magnetic field around itself, which is known as a solar bubble and encases the heliosphere, a magnetic sphere that is arguably the edge of the solar system. But like an embattled country, the borders of the solar system are controversial; where it ends depends on who you ask. When the probe appeared to exit the heliosphere, many cheered it on for leaving the solar system; others simply said it had entered interstellar space, the area beyond the heliosphere. NASA, in an announcement this week, hedged the debate: Voyager 1 has, beyond doubt, reached interstellar space, although it’s still within our solar system. Read More