Where in the Solar System Is Voyager 1?

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NASA photograph of one of the two identical Voyager space probes Voyager 1 and Voyager 2 launched in 1977.

There was a moment last week when the scientific community was on the edge of its seat after news that NASA's Voyager 1 had left the solar system. Voyager 1 is one of two spacecraft sent into the far reaches of the cosmos in the late 1970s to tour the solar system and collect data. Last week, a new study alleged that Voyager 1 had burst through the heliosphere into interstellar space. NASA quickly shot down that explanation.

"Voyager 1 is about 18 billion kilometers, or 11 billion miles, from the sun," said project scientist Edward Stone of NASA's Jet Propulsion Lab in Pasadena. "It's on the very edge of the bubble the sun creates around itself, called the heliosphere."  In other words, the craft remains well within the confines of the solar system, according to NASA.

But the study has sparked a debate over how exactly we know where the solar system ends and interstellar space begins. It's also brought the Voyager mission back into the limelight.

According to Stone, on August 25th, there was a major change in the environment surrounding Voyager, causing some to think it had moved outside of the bubble for the first time. "For 7 years, we’d seen a very intense field of radiation, which essentially disappeared on August 25th, suggesting that we might actually be outside the bubble for the first time. But it turns out that the magnetic field, once we measured it, was exactly the same as it had been…so we knew we were still inside the bubble but now connected to the outside for the first time."

Stone describes this change as a nice achievement. "It’s really almost a perfect vacuum as far as the spacecraft is concerned. Inside the bubble, we are surrounded by the magnetic field and the material that has come from the atmosphere of the sun. Outside, we will be embedded in the magnetic field of the galaxy and in material that has come from the explosion of supernova nearby, 5, 10, 15 million years ago."

"We listen to Voyager 1 about 8-10 hours every day. It’s sending back data on what is the magnet field, how many cosmic ray particles are out there…that’s the kind of data we're sending back every day."

Our Washington correspondent, Todd Zwillich, is filling in as host all this week. Follow Todd on Twitter for the latest from Capitol Hill.