Voyager 2 Reaches Interstellar Space and Sheds More Light on Outer Space

The spacecraft is only the second one to ever leave our heliosphere.

Exactly a year ago, on November 5, 2018, the Voyager 2 spacecraft became the second spacecraft ever to leave our heliosphere — the protective zone made up of particles and magnetic fields by our Sun. 

It entered interstellar space, and now, a year later, scientists have published five papers in Nature Astronomy about their findings. These papers detail the incredible discoveries Voyager 2 has made, and what scientists have observed.

Researchers from the University of Iowa have been carrying out this research. 

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Voyager 2's five operating instruments

Voyager 2 comes equipped with five different science operating instruments. These include a magnetic field sensor, two instruments that detect energetic particles from different energy ranges, and two instruments to observe plasma.

Altogether, the instruments assist scientists in painting a picture of what lies beyond our Sun's heliosphere: interstellar space.

Voyager 2 Reaches Interstellar Space and Sheds More Light on Outer Space
Voyager 1 and Voyager 2's location. Source: NASA/JPL-Caltech

Both the heliosphere and interstellar space are filled with plasma. The one in our heliosphere is hot and scattered, and in interstellar space, it is colder and more condensed. 

Voyager 2 picked up two big changes when it entered interstellar space last year: heliospheric particles dramatically dropped, and cosmic rays shot up and increased. This was when scientists knew it had entered a different region in space. 

This information adds on to what Voyager 1, Voyager 2's twin spacecraft, has been observing since it's been in space on a similar mission. 

"The Voyager probes are showing us how our Sun interacts with the stuff that fills most of the space between stars in the Milky Way galaxy," said Ed Stone, project scientist for Voyager and a professor of physics at Caltech. "Without this new data from Voyager 2, we wouldn't know if what we were seeing with Voyager 1 was characteristic of the entire heliosphere or specific just to the location and time when it crossed."

The observations of interstellar space

Thanks to the two Voyager spacecraft, we now know that plasma in interstellar space is denser and cooler than in our heliosphere.

We also now understand that the heliosphere is leaking particles. One of the Voyager's particle instruments picked up on particles trickling out of our heliosphere and into interstellar space. 

Thanks to Voyager 2's magnetic field instrument, findings from Voyager 1 have been confirmed. Scientists are now aware that the magnetic field just past the heliopause is parallel to the one inside the heliosphere.

Both Voyagers were launched in 1977 and are expected to stay in space for many more years to come. Their interstellar mission began in 1989.

Currently, Voyager 1 is located more than 22 billion kilometers (13.6 billion miles) from the Sun, and Voyager 2 is 18.2 billion kilometers (11.3 billion miles) from it. 

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