NASA’s Voyager 1 spacecraft officially is the first human-made object to venture into interstellar space. The 36-year-old probe is about 12 billion miles (19 billion km) from our sun.

New and unexpected data indicate Voyager 1 has been traveling for about one year through plasma, or ionized gas, present in the space between stars. Voyager is in a transitional region immediately outside the solar bubble, where some effects from our sun are still evident. A report on the analysis of these new data, an effort led by Don Gurnett and the plasma-wave science team at the University of Iowa, Iowa City, is published in the Sept. 12, 2013, edition of the journal Science.

“Now that we have new, key data, we believe this is mankind’s historic leap into interstellar space,” says 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.”

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