NASA's Voyager 1 is the most far-flung object ever launched, having spent the last 35 years putting upwards of 11-billion miles between itself and the Sun, soaring through space at speeds approaching 11 miles per second. Now, the Agency reports that Voyager has entered an entirely new region of space at the fringes of our solar system — the so-called "Magnetic Highway." Voyager scientists believe it could be the final region the spacecraft will have to traverse before reaching interstellar space.
We've written about Voyager 1's unprecedented journey into the space between star systems (known to astronomers as the "interstellar medium," or "ISM") before, so check there if you need a refresher on Voyager 1 and its mission of deep-space exploration. For the rest of you, here's a quick recap: for the last several years, Voyager 1 has been dancing on the edge of the heliosphere — a cosmic bubble of solar wind that surrounds our sun. The farther from the sun Voyager gets, the less solar wind it experiences, allowing high-energy electrons from the ISM to leak into the heliosphere and "push back" on the Sun's solar wind. Using Voyager 1's low-energy charged particle instrument as a sort of windsock for subatomic particles, NASA can get a feel for how the cosmic breezes are blowing at the spacecraft's current position.
Lately, those cosmic breezes have been... well... weird. In fact, the Voyager team announced yesterday that the spacecraft's instruments now indicate it has entered an entirely unprecedented region of space, dubbed "The Magnetic Highway."
Scientists refer to this new region as a magnetic highway for charged particles because our sun's magnetic field lines are connected to interstellar magnetic field lines. This connection allows lower-energy charged particles that originate from inside our heliosphere... to zoom out and allows higher-energy particles from outside to stream in. Before entering this region, the charged particles bounced around in all directions, as if trapped on local roads inside the heliosphere.
The Voyager team infers this region is still inside our solar bubble because the direction of the magnetic field lines has not changed. The direction of these magnetic field lines is predicted to change when Voyager breaks through to interstellar space.
In the video featured below, the Sun's lower-energy charged particles are depicted in pink, while particles from interstellar space are depicted in blue. Voyager can be seen entering the magnetic highway as inside and outside particles "zip and zoom" their way out of and into the heliosphere, respectively. As Voyager continues on its way, the ratio of blue particles to pink particles is projected to increase, and the direction of magnetic field lines surrounding the spacecraft are expected to shift their orientation.
Then again, this is uncharted territory — something that NASA is keenly aware of as it anticipates Voyager's arrival departure from our solar system:
"Although Voyager 1 still is inside the sun's environment, we now can taste what it's like on the outside because the particles are zipping in and out on this magnetic highway," said Edward Stone, Voyager project scientist, in a release. "We believe this is the last leg of our journey to interstellar space. Our best guess is it's likely just a few months to a couple years away. The new region isn't what we expected, but we've come to expect the unexpected from Voyager."