Voyager 2 Approaches the Interstellar Medium

Six years after Voyager 1 entered the interstellar medium, its twin, Voyager 2, also began recording an increase in the energy of its detected contaminated particles. This means it has approached the limits of the heliosphere. Since 2007, the probe has been in its outer layer (the region of space where the solar wind and the Sun’s magnetic fields are the main components of the medium).

At the boundary of the heliosphere, called the heliopause, the speed of the solar wind drops to virtually zero. Even further away, at a distance of more than 200 astronomical units from the Sun, lies the bow shock, where interstellar wind particles begin to slow down. After Voyager 2 leaves the heliosphere, it will become the second human-made object, after Voyager 1, to enter interstellar space.

Approximate locations of the Voyagers, October 2018 / NASA / JPL-Caltech

Scientists predict that Voyager 2 will enter the interstellar medium around the end of December. It is impossible to predict the exact timing of this event. Researchers can only rely on the data Voyager 1 has provided them over the past six years. However, it’s important to keep in mind that the spacecraft are located in different regions of the heliopause, the size of which depends on the 11-year solar activity cycle.

«We are observing changes in the environment around Voyager 2, there’s no doubt about that. However, at this point, the spacecraft is only on its way to the heliopause, and we can’t say exactly when it will reach it,» stated researchers monitoring the mission. «The only thing we can say with complete confidence is that we will receive a lot more interesting information in the coming months.»

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