Charged Particle Populations in and out of the New Region

This animated graphic shows the jumps and dips in two key populations of charged particles as NASA's Voyager 1 moved into and out of a new region called the "magnetic highway." The top graph (magenta) shows the prevalence of lower-energy charged particles that originate inside the heliosphere, which is the bubble of charged particles surrounding our sun. The bottom graph (blue) shows the prevalence of cosmic rays, which are higher-energy charged particles that originate from interstellar space. These data were obtained by Voyager 1's cosmic ray instrument.

Scientists refer to this new region as a "magnetic highway" because here the sun's magnetic field lines are connected to the interstellar magnetic field lines. This connection allows low energy particles from inside the heliosphere to zip away. It also allows cosmic ray particles from interstellar space to zoom in.

The populations of these particles began to change rapidly on July 28, 2012, when Voyager first entered this magnetic highway. Over the next few weeks, the new region lapped and receded from Voyager 1 like an ocean tide. The second step of the animation shows the profound dip in the inside particles and bump in outside particles in the magnetic highway region, with the crossing marked with a solid vertical line. The new region receded outward from Voyager within five days, as evidenced in the jump in inside particles and dip in outside particles (third step of the animation). The dashed line indicates when Voyager left the magnetic highway. By Aug. 13, Voyager 1 had re-entered the highway region, as shown in the fourth step of the animation. But, as shown in the fifth step, Voyager 1 left the region again on Aug. 20. In the sixth step of the animation, the graphic shows how Voyager 1 entered the new region for good on Aug. 25. Since then, the low-energy particles from inside have nearly vanished and the population of cosmic rays from outside has stabilized.

Image credit: NASA/JPL-Caltech/GSFC