NASA Voyager 1 Finally Leaves Solar System...Again

Voyager 1, the spacecraft currently travelling toward the far reaches of space, may have finally left our solar system. Scientists have announced that the craft has officially entered interstellar space, which could mean big news for researchers.

The Voyager 1 carries a gold plated phonograph record that contains greetings from Earth. In addition, the spacecraft has several scientific instruments, including the Low Energy Charged Particle detector. So far, Voyager 1 has traveled farther from Earth than any other human-made object and is now beginning its exploration of the galaxy beyond the sun's influence.

But how can we be sure that the spacecraft really has entered interstellar space? Whether Voyager 1 has left our solar system has been a source of controversy in the past. In fact, one previous model predicted that Voyager 1 entered interstellar space a little more than a year ago. Recent papers, though, seemed to indicate otherwise, revealing that it was still in the fuzzily-defined transition zone between the sun's sphere and the influence of the rest of the galaxy.

The main reason why this controversy has existed has been due to how we measure whether Voyager 1 has crossed the boundary. At 11 billion miles away, scientists aren't sure exactly what this boundary-crossing should look like. In theory, we should know when Voyager 1 has crossed the boundary when we stop seeing solar particles and start seeing galactic particles. In addition, we should see a change in the prevailing direction of the local magnetic field.

Yet these signs aren't always clear. Last summer, Voyager 1 recorded "multiple crossings of a boundary unlike anything previously observed," according to scientists. There were successive dips in and then subsequent recoveries in solar particle counts. Yet there was no change in the direction of the magnetic field.

Now, though, it seems that Voyager 1 has finally entered interstellar space. Scientists have recently constructed a model of the outer edge of the solar system that fits recent observations, both expected and unexpected.

"It's a somewhat controversial view, but we think Voyager has finally left the solar system, and is truly beginning its travels through the Milky Way," said Marc Swisdak, lead author of the new paper, in a news release.

The findings are published in The Astrophysical Journal.