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Voyager May Have Finally Left the Solar System

NASA still isn't sure, but a new study suggests it went interstellar last year.
Photo: NASA

If scientists at the University of Maryland are to be believed, man has finally succeeded at launching something out of the solar system.

Voyager I, launched in 1977 to explore the outer solar system and beyond, likely left the heliosphere and began exploring interstellar space on July 27, 2012, according to a paper published in The Astrophysical Journal Letters.

Scientists there say their findings "directly counter" recent findings by NASA, which suggest that Voyager is still being influenced by the sun's magnetic field.

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"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," Marc Swisdak, lead author of the paper, said.

In case you forgot, Voyager famously holds a gold-plated phonograph record containing greetings in various Earth languages, photos of humans and some of Earth's other species, and earth sounds such as babbling brooks and babies crying. It and its pal Voyager II, have discovered active volcanoes on Jupiter's moons, taught us more about Saturn's rings, and have just kept going. Voyager II was the only spacecraft to wave hello to Uranus and Neptune. Since then, both spacecraft, powered by nuclear energy, have just kept going, heading clear out of the solar system.

Here's where the latest controversy lies: Sometime last year, Voyager (whose scientific instruments miraculously still work) began reporting drops in the number of solar particles it was encountering, and an increase in the number of "galactic particles." Meanwhile, there was no change in the direction of the magnetic field Voyager was encountering, which would be a clear indication the spacecraft was being acted on by a body other than the sun.

A diagram of the heliopshere's makeup, via JPL

NASA's official line is that, because the number of solar particles eventually increased again, Voyager had simply entered a new stage of the heliosphere, which it called the "far reaches" of the solar system.

"This region was not anticipated, it was not predicted, we can't predict exactly when we'll [leave it]," Edward Stone, Voyager project scientist, said in December, eventually suggesting it could be in this stage for several years.

Swisdak and his colleagues have another explanation: They say that, more than 11 billion miles from the sun, things get weird. There's not a welcome-to-interstellar-space tourist trap, South of the Border-style at the end of the solar system. The area is extremely unstable, and invisible "islands" of magnetism arise out there, which would explain why the number of solar particles dropped and subsequently recovered.

Stone and NASA said in an official statement Thursday that Swisdak's study is "new and different from other models used so far to explain the data the spacecraft has been sending back from more than 11 billion miles (18 billion kilometers) away from our sun," which is a nice way of saying that for now, they're sticking to their earlier assessment.

"Their model would mean that the interstellar magnetic field direction is the same as that which originates from our sun," Stone said, adding that Swisdak's model "will become part of the discussion among scientists as they try to reconcile what may be happening."

And as long as NASA can keep finding new parts of the solar system, it can keep Voyager in the news: Unfortunately, the nearest star is roughly 73,000 years away. By the time Voyager reaches them, news will be beamed directly into your brain by Hyperloop train windows or something. Nah, that'd never happen.