NASA’s Voyager 2 spacecraft crossed into interstellar space last November. Now, one year later, scientists have published the first results from the data Voyager 2 gathered as it passed from the Sun’s sphere of influence out into interstellar space.
As the Sun blows charged particles into space, it carves a bubble out of the surrounding gas and dust. Earth and the other solar system planets are nestled inside this bubble, called the heliosphere. The boundary between the heliosphere and outside space is called the heliopause. And that’s what the Voyager spacecraft blew past.
Scientists are interested in the heliopause because it presents an opportunity to learn more about the Sun, interstellar space and the interactions between them.
What did we find?
Surprisingly what voyager 2 found was different from what voyager 1 found when it entered interstellar space.
When Voyager 1 crossed the heliopause in 2012 and measured magnetic fields inside and outside the boundary, there was no significant change in the direction of the magnetic fields. That surprised scientists because they expected some difference in direction of magnetic fields inside the heliosphere and those outside of it. But voyager 2 confirmed this finding.
What surprised astronomers more was the number of particles “leaking” out from the heliosphere into interstellar space. Even after Voyager 2 crossed the heliopause, it picked up particles coming from the Sun. Voyager 1, on the other hand, didn’t see such leakage. It’s still an open question why this leaking is happening.
There is still much for us to learn about the sun and the space beyond its influence.