Voyager 1 is currently cruising about 20 billion kilometres away into the deep, interstellar space. Its partner, Voyager 2 is also tagging close and on the verge of making an exit. Although it has no direct way of telling us much about space in that area, but it got there just in time to catch a rare flare-up in solar activity called Global Merged Interaction Region (GMIR) that enabled it to make one of its prime discoveries till date.
NASA astronomers have used the data from the Voyager probes to measure the pressure in heliosheath, the outer region of the solar system. For the first time, scientists were able to account for the total pressure that is exerted by the collision of force plasma, magnetic fields and particles like ions, cosmic rays and electrons on each other. What’s more, the pressure runs higher than expected.
Just like Earth has air pressure made up of air molecules drawn by gravity, space also has a pressure created by ions and electrons that when heated and accelerated by the Sun, create a giant balloon known as heliosphere. According to NASA, this zone extends millions of miles out past Pluto and at its edge, the Sun’s magnetic influence weakens due to particles from other stars and interstellar space.
Back in 2012, Voyager 2 caught a giant wave of coronal mass ejections in the GMIR. This wave caused the number of galactic cosmic waves to temporarily decrease. For months later, Voyager 1 picked up a similar decrease in observations, just across the solar system’s boundary in interstellar space. The scientists not only measured the pressure in the heliosheath, but also the speed of sound.