Voyager 1 May Be Caught Inside an Interstellar Flux Transfer Event

NASA’s most distant probe may not have left the Solar System after all, say astrophysicists

On 12 September 2013, NASA announced that the Voyager 1 spacecraft had entered a new region of space. The density of plasma in this region is much higher than is possible in the Solar System but about the level expected in interstellar space. So the probe must have finally left the Solar System, they said.

The news was greeted with the sound of champagne corks popping. But the celebrations may be have been premature. It turns out the evidence that Voyager 1 is beyond the Solar System isn’t quite as ironclad as NASA suggested.

Today Nathan Schwadron and David McComas at the Southwest Research Institute in Texas say that NASA’s conclusion doesn’t add up. They point out that while the plasma density has increased dramatically, the direction of the magnetic field in that region of space hasn’t changed at all.

That’s a problem because although astronomers have never directly measured the interstellar magnetic field, they’re pretty sure it must be significantly different from the Sun’s field which dominates inside the Solar System.

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