Voyager 1 Becomes First Manmade Object to Leave the Solar System, NASA Reports

After more than 30 years and 12 billion miles, NASA's Voyager 1 has officially left the solar system, the space agency reports.

In doing so, the spacecraft became the first human-made object to venture into interstellar space.

The announcement was made after new and unexpected data arose indicating that Voyager 1 has been traveling through plasma, or ionized gas, present in the space between stars for roughly one year now.

Based on this, scientists have concluded that the spacecraft is located in a transitional region immediately outside the solar bubble, or the area in which the effects of the Sun are still felt.

"Now that we have new, key data, we believe this is mankind's historic leap into interstellar space," said Ed Stone, Voyager project scientist based at the California Institute of Technology, Pasadena. "The Voyager team needed time to analyze those observations and make sense of them. But we can now answer the question we've all been asking -- 'Are we there yet?' Yes, we are."

Because Voyager 1 lacks a working plasma sensor, scientists had to come up with a different method to measure the the spacecraft's plasma environment and thus determine its location in space. The answer came in the form of a massive burst of solar wind and magnetic fields that erupted from the Sun in March 2012.

When this "unexpected gift" reached the spacecraft 13 months later, the plasma around Voyager 1 began to vibrate. Using its plasma wave instrument, Voyager 1 detected this movement, which allowed scientists to determine the density of the plasma based on the pitch of the oscillations. The results showed that the spacecraft was currently surrounded by plasma more than 40 times denser than that encountered in the outer layer of heliosphere, suggesting that the spacecraft had reached interstellar space.

Later that year, the plasma wave team reviewed its data and found an earlier, fainter set of oscillations. By extrapolating the measured plasma densities from these two events, the team officially determined that Voyager 1 first entered interstellar space in Aug. 2012.

"We literally jumped out of our seats when we saw these oscillations in our data -- they showed us the spacecraft was in an entirely new region, comparable to what was expected in interstellar space, and totally different than in the solar bubble," Gurnett said. "Clearly we had passed through the heliopause, which is the long-hypothesized boundary between the solar plasma and the interstellar plasma."
Related: Voyager 1 Left Solar System Last Year, Controversial Study Suggests