A model of the solar system’s edge using recent data. Voyager 1′s latest findings will likely rewrite this image, as soon as scientists figure out exactly what they mean. NASA/JPL/JHUAPL
If the solar wind was completely gone, galactic cosmic rays should be streaming in from all directions. Instead, Voyager found them coming preferentially from one direction. Furthermore, even though the solar particles had dropped off, the probe hasn’t measured any real change in the magnetic fields around it. That’s hard to explain because the galaxy’s magnetic field is thought to be inclined 60 degrees from the sun’s field.
No one is entirely sure what’s going on.
“It’s a huge surprise,” said astronomer Merav Opher of Boston University, who was not involved in the work. While the new observations are fascinating, they are likely something that theorists will debate about for some time, she added.
“In some sense we have touched the intergalactic medium,” Opher said, “but we’re still inside the sun’s house.”
Extending this analogy, it’s almost as if Voyager thought it was going outside but instead found itself standing in the foyer of the sun’s home with an open door that allows wind to blow in from the galaxy. Not only were scientists not expecting this foyer to exist, they have no idea how long the probe will stay inside of it. Stone speculated that the probe could travel some months or years before it reaches interstellar space.
“But it could happen any day,” he added. “We don’t have a model to tell us that.” Even then, Stone said, Voyager would not have really left the solar system but merely the region where the solar wind dominates.
For his part, Krimigis didn’t even want to speculate on what Voyager might encounter next because theorists’ models have so far not worked extremely well.
