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Voyager 1 left the solar system last year, research suggests

Voyager 1 is now in interstellar space, reports a new study that is at odds with NASA's findings, which places the venerable space probe just inside the sphere of our sun's influence.

By Mike / August 16, 2013

An artist's illustration of NASA's Voyager 1 spacecraft, the farthest human-built object from Earth, which launched in 1977 and is headed for interstellar space.


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While the handlers of NASA's venerable Voyager 1 spacecraft are still waiting for it to depart the solar system, a new study argues that the probe actually popped free into interstellar space last year.

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Voyager 1 left the sun's sphere of influence on July 27, 2012, according to the study, which employs a new model to explain and interpret the probe's data. The new model is different from NASA's take, which suggests Voyager 1 remains within the solar system, though just barely.

"It's a somewhat controversial view, but we think Voyager [1] has finally left the solar system, and is truly beginning its travels through the Milky Way," lead author Marc Swisdak of the University of Maryland said in a statement. [NASA's Voyager Probes: 5 Surprising Facts]

Swisdak and co-authors James Drake and Merav Opher — of the University of Maryland and Boston University, respectively — are not Voyager mission scientists. Their findings contrast with recent papers by the mission team and other researchers, which have concluded that the spacecraft is likely plying a strange transition zone at the edge of the solar system

A long journey

Voyager 1 and its twin, Voyager 2, launched a few weeks apart in 1977 to study Saturn, Jupiter, Uranus and Neptune. The duo completed this "grand tour" and then kept right on flying toward interstellar space.

Voyager 1 will get there first. It's about 11.6 billion miles (18.7 billion kilometers) from Earth, making it the farthest-flung manmade object in the universe. Voyager 2, for its part, is now 9.4 billion miles (15.2 billion km) from home.

Both spacecraft are exploring the outer layers of the heliosphere, the huge bubble of charged particles and magnetic fields emanating from the sun. But things are really getting interesting for Voyager 1; it has detected a dramatic drop in solar particles and a simultaneous jump in high-energy galactic cosmic rays, which originate from outside the solar system.

NASA's Voyager mission scientists don't think the probe has left the heliosphere yet, however, because it hasn't measured a shift in the direction of the ambient magnetic field. (The team thinks the observed magnetic field will change orientation from roughly east-west within the solar system to north-south outside of it.) 

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