Quirks & Quarks

After a 42-year journey, Voyager 2 goes interstellar

NASA's Voyager 2 spacecraft has joined its twin Voyager 1 and crossed out of the heliosphere and into interstellar space

NASA's Voyager 2 spacecraft has joined its twin Voyager 1 and crossed out of the heliosphere

Voyager 1 (top) and Voyager 2 (bottom) have now both left the heliosphere, the environment influenced by our Sun, and crossed into interstellar space (NASA/JPL-Caltech)

After 42 years and more than 18 billion kilometres, NASA's Voyager 2 spacecraft has crossed the barrier that separates the part of space dominated by our Sun from interstellar space.

Voyager 2's scientific instruments have helped create a picture of this cosmic shoreline. 

The Voyager missions 

The Voyager program included two spacecraft launched in 1977. Voyager 2 launched on August 20th and Voyager 1 on September 5th. The goal was to study the outer solar system, in particular the planetary systems of Jupiter and Saturn. Voyager 2 continued on to Uranus and Neptune.

Voyager 1 and 2 then went on to explore the outer boundary of the heliosphere. In 2012, Voyager 1 crossed that boundary into interstellar space, and one year ago, Voyager 2 did the same, as NASA just confirmed. 

Artist's concept of Voyager 2 in interstellar space (NASA)

You are now entering interstellar space

Interstellar space begins where the heliosphere, or the environment created by our Sun, ends. The heliosphere is formed by the solar winds that blow outward from the Sun at supersonic speeds. It meets the winds that blow inward from interstellar space generated from exploding stars from millions of years ago.

The two regions meet at the outer edge of the heliosphere called the heliopause, and this is where Voyager 2 crossed on November 5, 2018.

How far can Voyager go?

What did Voyager 2 find?

The heliosphere and the interstellar space regions are filled with different types of plasma, generated in different magnetic fields. Edward Stone, the project scientist for the Voyager mission since its inception in 1972 reports that Voyager 2 confirmed the plasma inside the heliosphere is hot and sparse, while in interstellar space it is colder and much more dense.

The spacecraft also indicated a layer at the edge of the heliopause where there is interaction between solar winds and interstellar winds. This was not observed by Voyager 1. Voyager 2 also found a stronger magnetic field from interstellar space than was previously recorded by Voyager 1.  

 

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